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3. Additional Resources

1. EE Used memory 203MB of 631 MB EE Used swap Obytes of 1 2GB Devices Name Directory Type Total Used dev sdal boot ext3 98 3MB 91MB ff 9 none dev shm tmpfs 315 MB 0 bytes dev mapper VolGroup00 LogVol00 ext3 11 1GB 6 0GB Figure 39 2 GNOME System Monitor Resources tab 3 File Systems The a command reports the system s disk space usage If you type the command af at a shell prompt the output looks similar to the following Filesystem 1K blocks Used Available Use Mounted on dev mapper VolGroup00 LogVol00 11675568 6272120 4810348 57 dev sdal 100691 9281 86211 10 boot none 322856 0 322856 0 dev shm By default this utility shows the partition size in 1 kilobyte blocks and the amount of used and available disk space in kilobytes To view the information in megabytes and gigabytes use the command df h The n argument stands for human readable format The output looks similar to the following 383 Chapter 39 Gathering System Filesystem Size Used Avail Use Mounted on dev mapper VolGroup00 LogVol100 12G 6 0G 4 6G 57 dev sdal 99M 9 1M 85M 10 boot none 316M 0 316M 0 dev shm In the list of mounted partitions there is an entry for dev shm This entry represents the system s virtual memory file system The du command displays the estimated amount of space being used by files in a directory If you type du at a shell prompt the disk usage for each of th
2. After you provide the correct information a self signed certificate is created in etc httpd conf ssl crt server crt Restart the secure server after generating the certificate with following the command sbin service httpd restart 9 Testing The Certificate To test the test certificate installed by default either a CA signed certificate or a self signed certificate point your Web browser to the following home page replacing server example com with your domain name https server example com 285 Chapter 25 Apache HTTP Secur Note Note the s after http The https prefix is used for secure HTTP transactions If you are using a CA signed certificate from a well known CA your browser probably automatically accepts the certificate without prompting you for input and creates the secure connection Your browser does not automatically recognize a test or a self signed certificate because the certificate is not signed by a CA If you are not using a certificate from a CA follow the instructions provided by your browser to accept the certificate Once your browser accepts the certificate your secure server displays a default home page 10 Accessing The Server To access your secure server use a URL similar to the following https server example com Your non secure server can be accessed using an URL similar to the following http server example com The standard port for secure Web communica
3. cccccceeceeeeeeeeeaeeeeeeeeeeeeeeeaeaaeeees 29 8 1 Creating Kickstart Boot Media ccceceeeceeeeeeeeeeeeeeeaeaaenteeeeeees 29 8 2 Making the Kickstart File Available on the Network 00066 30 9 Making the Installation Tree Available cccececeeeeeeeaeeeeeeeeeeeeeeeaeaaeeees 31 10 Starting a Kickstart Installation 0 cece ceeeeeee cece eceeeeeeeeeeeeeaeaaenneneeeees 31 2 Kickstart Configurator assisiccdseccdicessesdeeeden otasini tinetaae sae a ered sbasieeeentanes 35 1 Basic Configuration cece cece eeeeee cece ee eee eeeeeeeeeeeeaeaaeeeeeeeeeeeaeaaaaneneeees 35 2 Installation Method enea eee eeeeeeaaeeeeceaaeeeeeeaaeeeeeeaeeeeaeaaees 36 3 Boot Loader Optom csceisaizapedccd scdeadatvandedeescceiaateanedeeescadidaevanvedeexdeignleanys 38 A Partition IMfOrMAtiON reren a EE ERANT 40 4 1 Creating Partitions s cccissesceccest eyocevassneceant ey cadh waa exeesbepceeaavaaedeentenes 40 5 Network Configuration cccccecceeeeeeeeeeeeeeeaeaaeeeeeeeeeeeeaeaaeeneeeeeeeeeaeaaeaees 44 6 Authentication sess caccdecies et elaenteneteahdeulaadoecsnasedos eluavencvaehd danii eaii aiaa 45 7 Firewall Configuration 0 ccccccceceeeeeeeeeeeeeeeaeeaeeeeeeeeeeeeaeaaeeneeeeeeeeeaeaaeeees 47 7 1 SELINUX Configuration cece cece cece sees aeaaeeeeeeeeeeeeaeaaeaneeeeeees 48 8 Display Configuration cccceccceeeeeeeeeeeee ee ae aa eeeeeeeeeeeeaeaaeeeeeseeeeeeaeaa
4. ccecececeee cece cece cece eee eeeeeeeeeeeeaaaaeeeeeeeeeeeeaaa 258 252 NB OQGING eaS 260 2 3 Environment Variables cccccceeeeeeeeaeeeeeeeeeeeeeeeaaaaeeneeeeeeeeeaea 262 2 4 Directories sce siaegleeveitedsvie dines eet viel el esate 264 3 Virtual Hosts SettingS srian renean anaa a aaa aaa aaa aai 266 3 1 Adding and Editing a Virtual Host seesseeeeeeeeeesserreeesrrseesrrnnn 267 4 Server Settings 00 ccc eeeeececeaeeeeeeeeeeeeeceaeaaaaeeeeeeeeseaaaaaaaaeeeeeeseaeaaaaees 270 5 Perormance TUNING sorea ea S 272 6 Saving Yo r Settings sseeeseinianeni a speeded n N E EE 273 7 Additional Resources ncen R 274 7 1 Installed Documentation sssrinin 274 2 Usetul Websites iieccevecesstuvedestcedevint bevievas EAEEREN UERR ESE 274 7 3 Related BOOKS cceeeeeeeeeeeeeeeeeeee erence ee eeeeee ee eeaaeeeeesaaeeeeenees 274 25 Apache HTTP Secure Server Configuration ccceceeeeeeeeeeneeeeeeeeeeeeeeaes 275 APU i gole V ci le ginerreeee rene rrtere heart arere en mercer rere errr eee err terre errr 275 2 An Overview of Security Related Packages cceccseeeeeeeeeeeeeeaeeaeeees 275 3 An Overview of Certificates and Security ccceceeeeseeeeeeeeeeeeeeaeeaeeees 278 4 Using Pre Existing Keys and Certificates 0 ccceceeecseeeeeeeeeeeeeeaeeeeeees 278 5 Types Of Certificates 2 2 eececceeeeeeeeneeeeeeeeeeeeaeaaeeteeeeeeeeeseaaaaneteeeeeeeeeaaa 279 6 Generating a Key
5. part swap size 128 ondisk sda part swap size 128 ondisk sdb part swap size 128 ondisk sdc part reel Li size 1 grow ondisk sda jee ielalel 2 size l grow ondisk sdb partirai size 1 grow ondisk sdc manel level 1 device md0 raid 01 raid 02 raid 03 raid usr level 5 device md1 raid 11 raid 12 raid 13 For a detailed example of raid in action refer to Section 4 1 Advanced Partitioning Example reboot optional Reboot after the installation is successfully completed no arguments Normally during a manual installation anaconda displays a message and waits for the user to press a key before rebooting The reboot option is roughly equivalent to the shutdown r command Note Use of the reboot option may result in an endless installation loop depending on the installation media and method The reboot option is the default completion method if no other methods are explicitly specified in the kickstart file For other completion methods refer to the halt poweroff and shutdown kickstart options rootpw required Sets the system s root password to the lt password gt argument rootpw iscrypted lt password gt 20 Kickstart Options iscrypted If this is present the password argument is assumed to already be encrypted selinux optional Sets the system s SELinux mode to one of the following arguments enforcing Enables SELinux with the de
6. 147 Chapter 15 Package Managemen Note To query a package replace foo with the actual package name Instead of specifying the package name use the following options with q to specify the package s you want to query These are called Package Selection Options a queries all currently installed packages f lt file gt queries the package which owns lt file gt When specifying a file you must specify the full path of the file for example bin 1s p lt packagefile gt queries the package lt packagefile gt There are a number of ways to specify what information to display about queried packages The following options are used to select the type of information for which you are searching These are called Information Query Options i displays package information including name description release size build date install date vendor and other miscellaneous information 1 displays the list of files that the package contains s displays the state of all the files in the package a displays a list of files marked as documentation man pages info pages READMEs etc c displays a list of files marked as configuration files These are the files you change after installation to adapt the package to your system for example sendmail cf passwd inittab etc For the options that display lists of files add v to the command to display the lists in a familiar ls 1 format 2 7 Verifyin
7. 267 Chapter 24 Apache HTTP Serve The Webmasier email address corresponds to the serverAdmin http httpd apache org docs 2 0 mod core html serveradmin directive within the virtualHost http httpd apache org docs 2 0 mod core html virtualhost directive This email address is used in the footer of error pages if you choose to show a footer with an email address on the error pages In the Host Information section choose Default Virtual Host IP based Virtual Host or Name based Virtual Host Default Virtual Host You should only configure one default virtual host remember that there is one setup by default The default virtual host settings are used when the requested IP address is not explicitly listed in another virtual host If there is no default virtual host defined the main server settings are used IP based Virtual Host If you choose IP based Virtual Host a window appears to configure the lt VirtualHost gt http httpd apache org docs 2 0 mod core html virtualhost directive based on the IP address of the server Specify this IP address in the IP address field To specify multiple IP addresses separate each IP address with spaces To specify a port use the syntax rp Address Port Use colon asterisk to configure all ports for the IP address Specify the host name for the virtual host in the Server Host Name field Name based Virtual Host If you choose Name based Virtual Host a window appears to configu
8. 88 Creating the LVM Physical Volumes Add Partition Mount Point lt Not Applicable gt File System Type physical volume LVM sda 8676 MB IBM PSG ST39103LC C sdb 8676 MB IBM PSG ST39204LC Allowable Drives Size MB 100 Additional Size Options O Fixed size Fill all space up to MB Fill to maximum allowable size _ Force to be a primary partition Figure 8 5 Creating a Physical Volume 3 You cannot enter a mount point yet you can once you have created all your physical volumes and then all volume groups 4 A physical volume must be constrained to one drive For Allowable Drives select the drive on which the physical volume are created If you have multiple drives all drives are selected and you must deselect all but one drive 5 Enter the size that you want the physical volume to be 6 Select Fixed size to make the physical volume the specified size select Fill all space up to MB and enter a size in MBs to give range for the physical volume size or select Fill to maximum allowable size to make it grow to fill all available space on the hard disk If you make more than one growable they share the available free space on the disk 7 Select Force to be a primary partition if you want the partition to be a primary partition 8 Click OK to return to the main screen Repeat these steps to create as many physical volumes as needed for your LVM setup For 89 C
9. Formatting the partition permanently destroys any data that currently exists on the partition 1 2 3 Labeling the Partition Next give the partition a label For example if the new partition is dev sda and you want to label it work e2label dev sda6 work By default the installation program uses the mount point of the partition as the label to make sure the label is unique You can use any label you want 1 2 4 Creating the Mount Point As root create the mount point mkdir work 1 2 5 Add to etc tstab As root edit the etc fstab file to include the new partition The new line should look similar to the following LABEL work work ext3 defaults i 2 The first column should contain LABEL followed by the label you gave the partition The second column should contain the mount point for the new partition and the next column should be the file system type for example ext3 or swap If you need more information about the format read the man page with the command man fstab If the fourth column is the word defaults the partition is mounted at boot time To mount the partition without rebooting as root type the command mount work 1 3 Removing a Partition 119 Chapter 12 Managing Disk Storage Warning i Do not attempt to remove a partition on a device that is in use Before removing a partition boot into rescue mode or unmount any partitions on the device and turn off
10. C System clock uses UTC Figure 28 3 Timezone Properties If your system clock is set to use UTC select the System clock uses UTC option UTC stands for the Universal Time Coordinated also known as Greenwich Mean Time GMT Other time zones are determined by adding or subtracting from the UTC time 309 310 Chapter 29 Keyboard Configuration The installation program allows users to configure a keyboard layout for their systems To configure a different keyboard layout after installation use the Keyboard Configuration Tool To start the Keyboard Configuration Tool select Applications the main menu on the panel gt System Settings gt Keyboard or type the command system config keyboard at a shell prompt Figure 29 1 Keyboard Configuration Select a keyboard layout from the list for example U S English and click OK For changes to take effect you should log out of your graphical desktop session and log back in 311 312 Chapter 30 Mouse Configuration The installation program allows users to select the type of mouse connected to the system To configure a different mouse type for the system use the Mouse Configuration Tool To start the Mouse Configuration Tool type the command system config mouse ata shell prompt for example in an XTerm or GNOME terminal If the X Window System is not running the text based version of the tool is started Figure 30 1 Mouse Confi
11. Figure 17 12 Wireless Settings 7 On the Configure Network Settings page choose between DHCP and static IP address You may specify a hostname for the device If the device receives a dynamic IP address each time the network is started do not specify a hostname Click Forward to continue 8 Click Apply on the Create Wireless Device page After configuring the wireless device it appears in the device list as shown in Figure 17 13 Wireless Device 177 Chapter 17 Network Configuration File Profile Help s f Be X New Edit Copy Delete Activate Deactivate ces Hardasre Pec NS Hosts You may configure network devices associated with physical hardware here Multiple logical devices can be associated with a single piece of hardware ran Tome avane ome Inactive ethO ethd Wireless Figure 17 13 Wireless Device Be sure to select File gt Save to save the changes After adding the wireless device you can edit its configuration by selecting the device from the device list and clicking Edit For example you can configure the device to activate at boot time When the device is added it is not activated immediately as seen by its Inactive status To activate the device select it from the device list and click the Activate button If the system is configured to activate the device when the computer starts the default this step does not have to be performed again 8 Managing DNS Settin
12. Figure 40 1 OProfile Setup On the right side of the tab select the Profile kernel option to count events in kernel mode for the currently selected event as discussed in Section 2 3 Separating Kernel and User space Profiles f this option is unselected no samples are collected for the kernel Select the Profile user binaries option to count events in user mode for the currently selected event as discussed in Section 2 3 Separating Kernel and User space Profiles f this option is unselected no samples are collected for user applications Use the Count text field to set the sampling rate for the currently selected event as discussed in Section 2 2 1 Sampling Rate If any unit masks are available for the currently selected event as discussed in Section 2 2 2 Unit Masks they are displayed in the Unit Masks area on the right side of the Setup tab Select the checkbox beside the unit mask to enable it for the event On the Configuration tab to profile the kernel enter the name and location of the vmlinux file for the kernel to monitor in the Kernel image file text field To configure OProfile not to monitor the kernel select No kernel image 401 Chapter 40 OProfile Configuration Kernel image file boot vmlinux 2 4 21 1 1931 2 349 2 2 entsmp E C No kernel image C Verbose Per application kernel samples files C Per application shared libs samples files Profiler running 1
13. Ollepackages too i 0 1 1386 wom 2 5 Freshening Freshening a package is similar to upgrading one Type the following command at a shell prompt wom Irwin tool 2 1 1386 om RPM s freshen option checks the versions of the packages specified on the command line against the versions of packages that have already been installed on your system When a newer version of an already installed package is processed by RPM s freshen option it is upgraded to the newer version However RPM s freshen option does not install a package if no previously installed package of the same name exists This differs from RPM s upgrade option as an upgrade does install packages whether or not an older version of the package was already installed RPM s freshen option works for single packages or package groups If you have just downloaded a large number of different packages and you only want to upgrade those packages that are already installed on your system freshening does the job If you use freshening you do not have to delete any unwanted packages from the group that you downloaded before using RPM In this case issue the following command wo IWIN e a oN RPM automatically upgrades only those packages that are already installed 2 6 Querying Use the rpm q command to query the database of installed packages The rpm q foo command displays the package name version and release number of the installed package foo LOO Z 6 Oil
14. iptables A FORWARD i ethl j ACCEP root myServer iptables A FORWARD o ethl j ACCEP This rule gives systems behind the firewall gateway access to the internal network The gateway routes packets from one LAN node to its intended destination node passing all packets through its eth1 device Note By default the IPv4 policy in Red Hat Enterprise Linux kernels disables support for IP forwarding This prevents machines that run Red Hat Enterprise Linux from functioning as dedicated edge routers To enable IP forwarding use the following command root myServer sysctl w net ipv4 ip_forward 1 This configuration change is only valid for the current session it does not persist beyond a reboot or network service restart To permanently set IP forwarding edit the etc sysct1 conf file as follows Locate the following line net ipv4 ip_forward 0 Edit it to read as follows net ipv4 ip_forward 1 Use the following command to enable the change to the sysct1 conf file 199 Chapter 18 Firewalls root myServer sysctl p etc sysctl conf 5 1 Postrouting and IP Masquerading Accepting forwarded packets via the firewall s internal IP device allows LAN nodes to communicate with each other however they still cannot communicate externally to the Internet To allow LAN nodes with private IP addresses to communicate with external public networks configure the firewall for P masqueradin
15. 4 Kickstart Options The following options can be placed in a kickstart file If you prefer to use a graphical interface for creating your kickstart file use the Kickstart Configurator application Refer to Chapter 2 Kickstart Configurator for details Note If the option is followed by an equals mark a value must be specified after it Kickstart Options In the example commands options in brackets are optional arguments for the command autopart optional Automatically create partitions 1 GB or more root partition a swap partition and an appropriate boot partition for the architecture One or more of the default partition sizes can be redefined with the part directive ignoredisk optional Causes the installer to ignore the specified disks This is useful if you use autopartition and want to be sure that some disks are ignored For example without ignoredisk attempting to deploy on a SAN cluster the kickstart would fail as the installer detects passive paths to the SAN that return no partition table The ignoredisk option is also useful if you have multiple paths to your disks The syntax is ignoredisk drives drivel drive2 where driven is one of sda sdb hda ete autostep optional Similar to interactive except it goes to the next screen for you It is used mostly for debugging auth OF authconfig required Sets up the authentication options for the sy
16. If the printer has been automatically detected the printer model appears in Select Connection Select the printer model and click Forward to continue If the device does not automatically appear select the device to which the printer is connected such as LPT 1 or Serial Port 1 in Select Connection Queue type Select a queue type Locally connected z dev Ip0 Rescan devices Custom device Figure 33 3 Adding a Local Printer Next select the printer type Refer to Section 5 Selecting the Printer Model and Finishing for details 2 Adding an IPP Printer An IPP printer is a printer attached to a different system on the same TCP IP network The system this printer is attached to may either be running CUPS or simply configured to use IPP If a firewall is enabled on the printer server then the firewall should be configured to allow send receive connections on the incoming UDP port 631 If a firewall is enabled on on the client the system sending the print request then the firewall must be allowed to accept and create connections through port 631 339 Chapter 33 Printer Configuration You can add a networked IPP printer by clicking the New Printer button in the main Printer Configuration Tool window to display the window in Figure 33 2 Adding a Printer Enter the Printer Name printer names cannot contain spaces and may contain letters numbers dashes and underscores _ De
17. The physical volumes are combined into logical volume groups with the exception of the boot partition The boot partition cannot be on a logical volume group because the boot loader cannot read it If the root partition is on a logical volume create a separate boot partition which is not a part of a volume group Since a physical volume cannot span over multiple drives to span over more than one drive create one or more physical volumes per drive Physical Volume Physical Volume Physical Volume boot 9 1 GB 9 1 GB 9 1 GB 75 MB ext3 Logical Volume Group 9 1 GB x 3 75 MB Figure 7 1 Logical Volume Group The logical volume group is divided into logical volumes which are assigned mount points such as home and m and file system types such as ext2 or ext3 When partitions reach their full capacity free space from the logical volume group can be added to the logical volume to increase the size of the partition When a new hard drive is added to the system it can be added to the logical volume group and partitions that are logical volumes can be expanded 79 Chapter 7 Logical Volume Man Logical Volume Group 9 1 GB x 3 75 MB Logical Volume Logical Volume Free Space home i 20 GB 2 GB 5 GB Figure 7 2 Logical Volumes On the other hand if a system is partitioned with the ext3 file system the hard drive is divided into partitions of defined sizes If a partition becomes full it is n
18. Upgradability Using RPM you can upgrade individual components of your system without completely reinstalling When you get a new release of an operating system based on RPM such as Red Hat Enterprise Linux you do not need to reinstall on your machine as you do with operating systems based on other packaging systems RPM allows intelligent fully automated in place upgrades of your system Configuration files in packages are preserved across upgrades so you do not lose your customizations There are no special upgrade files needed to upgrade a package because the same RPM file is used to install and upgrade the package on your system Powerful Querying RPM is designed to provide powerful querying options You can do searches through your 141 Chapter 15 Package Managemen entire database for packages or just for certain files You can also easily find out what package a file belongs to and from where the package came The files an RPM package contains are in a compressed archive with a custom binary header containing useful information about the package and its contents allowing you to query individual packages quickly and easily System Verification Another powerful feature is the ability to verify packages If you are worried that you deleted an important file for some package verify the package You are notified of any anomalies At that point you can reinstall the package if necessary Any configuration files that you
19. winbindtemplateshell lt bin false gt Shell that winbind users have as their default login shell enablewinbindusedefaultdomain Configures winbind to assume that users with no domain in their usernames are domain users disablewinbindusedefaultdomain Configures winbind to assume that users with no domain in their usernames are not domain users winbindjoin lt Administrator gt Joins the winbind domain or ADS realm now as this administrator 294 Command Line Version Option Description enablewins Enable WINS for hostname resolution disablewins Disable WINS for hostname resolution enablehesiod Enable Hesiod disablehesiod Disable Hesiod hesiodlhs lt lhs gt Specify Hesiod LHS hesiodrhs lt rhs gt Specify Hesiod RHS enablecache Enable nscd disablecach Disable nsca nostart Do not start or stop the portmap ypbind Of nscd services even if they are configured kickstart Do not display the user interface probe Probe and display network defaults Table 26 1 Command Line Options 295 296 Part V System Configuration Part of a system administrator s job is configuring the system for various tasks types of users and hardware configurations This section explains how to configure a Red Hat Enterprise Linux system Chapter 27 Console Access When normal non root users lo
20. For example assume you check rsync to enable it in runlevel 3 and then save the changes The rsync service is immediately enabled The next time xinetd is started rsync is still enabled Warning When you save changes to xinetd services xinetd is restarted and the changes take place immediately When you save changes to other services the runlevel is reconfigured but the changes do not take effect immediately To enable a non xinetd service to start at boot time for the currently selected runlevel check the checkbox beside the name of the service in the list After configuring the runlevel apply the changes by selecting File gt Save Changes from the pulldown menu The runlevel configuration is changed but the runlevel is not restarted thus the changes do not take place immediately For example assume you are configuring runlevel 3 If you change the value for the httpd service from checked to unchecked and then select Save Changes the runlevel 3 configuration changes so that httpd is not started at boot time However runlevel 3 is not reinitialized so httpd is still running Select one of following options at this point 1 Stop the nttpd service Stop the service by selecting it from the list and clicking the Stop button A message appears stating that the service was stopped successfully 2 Reinitialize the runlevel Reinitialize the runlevel by going to a shell prompt and typing the command telinit 3 where 3 is
21. cece eeeeceeeee cece ceeeeeeeeeeeee ee aeaa ee teeeeeeeeeaeaaaaeeeeeeeeeeeeaaa 281 7 Generating a Certificate Request to Send to a CA eee eceeeecceeseeeeeeeeees 282 8 Creating a Self Signed Certificate 0 cceeececcceeeeeeeeeee sees ae eeeeeeeeeeeeeeaae 284 9 Testing The Certificate 0 00 0 cccceceeeeeeeee cece ae aaeeeeeeeeeeeseaaaaieteeeeeeeeeaaa 285 10 Accessing The Server cccecceeeeeeaeeeeeeeeeeeeeeeaeaaeeeeeeeeeeeaeaaaaeeeeeees 286 11 Additional Resources 20 2 cece ee cece cece cece nee eeeeeeeeeeaeaaaeeceeeeseeaeaaeaeeeeeees 286 11 4 Useful WebSites isscisesseicoresbicectedeecoce e aa EA aa aaa 287 11 2 Related BOOKS cerctsosers toe een 287 26 Authentication Configuration ccccccceeeeeeeeeeeeee ee aeeeeeeeeeeeeeeeaaaaeeneeeeeeeeeaas 289 1 User Information cceecccccecceeeeee cece ee ae ea eeeeeeeeeeeeaeaaeegeseeeeeeeaeaanneeeeeees 289 2 UTNE MICALION os scien nse vacctceceauvnpdeasdonnet esate deb saaeevedesuveg sss aeeenstenace dabeaaedeevess 291 3 Command Line Version cccceeeeeeeeeee cece ae eeeeeeeeeeeeeeaaaaeeeeeeeeeeeeaeaaeaees 292 V System Contiguratiom 2 c 2seei erinan aa E E tise eden iR 297 27 CONSOlE ACCESS secdesiicisctaaheveddeadaeiataavextdeas a Aa Ea AEEA E E AE A EAA ee 299 1 Disabling Shutdown Via Ctrl Alt Del 0 2c cecceeeeeeeeeeeeeeaaeeeeeeeeees 299 2 Disabling Console Program ACCESS c eceeeeeeeeeeeeaeeeeeeee
22. gt System Tools gt Kickstart or type the command usr sbin system config kickstart As you are creating a kickstart file you can select File gt Preview at any time to review your current selections To start with an existing kickstart file select File gt Open and select the existing file 1 Basic Configuration Eile Help Installation Method Default Language Boot Loader Options Keyboard Partition Information Network Configuration Mouse Authentication Firewall Configuration r Time Zone Display Configuration Package Selection Pre Installation Script Root Password Post Installation Script Confirm Password Language Support Basic Configuration Basic Configuration required English USA U S English Generic Wheel Mouse PS 2 BIBIE C Emulate 3 Buttons America New_Y ork lt O Use UTC clock Encrypt root password O Lao Laos O Latvian Latvia Lithuanian Target Architecture E m BE 4 x86 AMD64 or Intel EM64T Reboot system after installation C Perform installation in text mode graphical is default C Perform installation in interactive mode Figure 2 1 Basic Configuration 35 Chapter 2 Kickstart Configurator Choose the language to use during the installation and as the default language to be used after installation from the Default Language menu Select the system keyboar
23. For more information on disk quotas refer to the following resources 3 1 Installed Documentation The quotacheck edquota repquota quota quotaon and quotaoff man pages 3 2 Related Books e Red Hat Enterprise Linux Introduction to System Administration Red Hat Inc Available at http www redhat com docs and on the Documentation CD this manual contains background information on storage management including disk quotas for new Red Hat Enterprise Linux system administrators 131 132 Chapter 14 Access Control Lists Files and directories have permission sets for the owner of the file the group associated with the file and all other users for the system However these permission sets have limitations For example different permissions cannot be configured for different users Thus Access Control Lists ACLs were implemented The Red Hat Enterprise Linux 5 0 0 kernel provides ACL support for the ext3 file system and NFS exported file systems ACLs are also recognized on ext3 file systems accessed via Samba Along with support in the kernel the acl package is required to implement ACLs It contains the utilities used to add modify remove and retrieve ACL information The cp and mv commands copy or move any ACLs associated with files and directories 1 Mounting File Systems Before using ACLs for a file or directory the partition for the file or directory must be mounted with ACL support
24. Package Selection Confirm Password Pre Installation Script L Encrypt GRUB password Post Installation Script i aca aa Install boot loader on Master Boot Record MBR Install boot loader on first sector of the boot partition Kernel parameters Figure 2 3 Boot Loader Options GRUB is the default boot loader for Red Hat Enterprise Linux If you do not want to install a boot loader select Do not install a boot loader If you choose not to install a boot loader make sure you create a boot diskette or have another way to boot your system such as a third party boot loader You must choose where to install the boot loader the Master Boot Record or the first sector of the boot partition Install the boot loader on the MBR if you plan to use it as your boot loader To pass any special parameters to the kernel to be used when the system boots enter them in the Kernel parameters text field For example if you have an IDE CD ROM Writer you can tell the kernel to use the SCSI emulation driver that must be loaded before using cdrecord by configuring hdd ide scsi as a kernel parameter where hdd is the CD ROM device You can password protect the GRUB boot loader by configuring a GRUB password Select Use GRUB password and enter a password in the Password field Type the same password in the Confirm Password text field To save the password as an encrypted password in the file select Encrypt GRUB password If the encryption optio
25. Red Hat Enterprise Linux 5 0 0 uses the Common Unix Printing System CUPS If a system was upgraded from a previous Red Hat Enterprise Linux version that used CUPS the upgrade process preserves the configured queues Using Printer Configuration Tool requires root privileges To start the application select System on the panel gt Administration gt Printing or type the command system config printer at a shell prompt Edit Delete Default Apply printer my my printer Figure 33 1 Printer Configuration Tool The following types of print queues can be configured AppSocket HP JetDirect a printer connected directly to the network through HP JetDirect or Appsocket interface instead of a computer Internet Printing Protocol IPP a printer that can be accessed over a TCP IP network via the Internet Printing Protocol for example a printer attached to another Red Hat Enterprise Linux system running CUPS on the network e LPD LPR Host or Printer a printer attached to a different UNIX system that can be accessed over a TCP IP network for example a printer attached to another Red Hat Enterprise Linux system running LPD on the network Networked Windows SMB a printer attached to a different system which is sharing a 337 Chapter 33 Printer Configuration printer over an SMB network for example a printer attached to a Microsoft Windows machine e Networked JetDirect a printer connected
26. The RPM Package Manager RPM is an open packaging system available for anyone to use which runs on Red Hat Enterprise Linux as well as other Linux and UNIX systems Red Hat Inc encourages other vendors to use RPM for their own products RPM is distributable under the terms of the GPL For the end user RPM makes system updates easy Installing uninstalling and upgrading RPM packages can be accomplished with short commands RPM maintains a database of installed packages and their files so you can invoke powerful queries and verifications on your system If you prefer a graphical interface you can use the Package Management Tool to perform many RPM commands During upgrades RPM handles configuration files carefully so that you never lose your customizations something that you cannot accomplish with regular tar gz files For the developer RPM allows you to take software source code and package it into source and binary packages for end users This process is quite simple and is driven from a single file and optional patches that you create This clear delineation between pristine sources and your patches along with build instructions eases the maintenance of the package as new versions of the software are released Note Because RPM makes changes to your system you must be root to install remove or upgrade an RPM package 1 RPM Design Goals To understand how to use RPM it can be helpful to understand RPM s design goals
27. and snapshot directories by adding them to etc exports For example diskless i386 RHEL4 AS root ro sync no_root_squash diskless i386 RHEL4 AS snapshot rw sync no_root_squash Replace with one of the hostname formats discussed in Section 3 2 Hostname Formats Make the hostname declaration as specific as possible so unwanted systems can not access the NFS mount If the NFS service is not running start it service nfs start If the NFS service is already running reload the configuration file service nfs reload 2 Finish Configuring the Diskless Environment To use the graphical version of the Network Booting Tool you must be running the X Window System have root privileges and have the system config netboot RPM package installed To start the Network Booting Tool from the desktop go to Applications the main menu on the panel gt System Settings gt Server Settings gt Network Booting Service Or type the command system config netboot at a shell prompt for example in an XTerm or a GNOME terminal If starting the Network Booting Tool for the first time select Diskless from the First Time Druid Otherwise select Configure gt Diskless from the pull down menu and then click Add A wizard appears to step you through the process 1 Click Forward on the first page 64 Adding Hosts 2 On the Diskless Identifier page enter a Name and Description for the diskless e
28. cccceeeeeeeeeee sees ee eeeeeeeeeeeeeaaaaeeeeeseeeeeeaaa 242 4 Additional R6SOUICES crinis naini dete E EEA 242 4 1 Installed Documentation ssssssirrriieiikeinninn niian 242 4 2 Useful Websites sessssnesrseecrrsrnerrrnsernrnnnnnnnnsnnnnnnnnnnnnnnnnnnnnnenna 242 23 Dynamic Host Configuration Protocol DHCP sssssssssssesssssrrsreresesrsrrrrres 245 1 Why US6 DIC Pit orent eoe a E E a 245 2 Configuring a DHCP Server 0ccccceeeeeceeceeeeeeeeeeeeeeaeeaeeeeeeeeeeeeaeaaeeees 245 2 1 Configuration File cccccecceeeeeeeeeeeeee ee ae ee eeeeeeeeeeeeaaaaeeeeeeeeeeeeaaa 245 22 Lease Database ese 249 2 3 Starting and Stopping the Server c ceceeeeeeeeeaeeeeeeeeeeeeeeeaea 250 2 4 DHCP Relay Agent cccceceeeeeeeee tees eee eeeeeeeeeeeeaaaaeeneeeeeeeeeaea 251 3 Configuring a DHCP Client 0 2 0 00 ceccceeececeeeeeeeeeeeeeeeeeaeeaeeeeeeeeeeeeaeaaeeees 251 4 Additional RESOUrCES eee eee ee ce ceeeee cece ee ee tree cain eeeeaaeeeeeeaaaeeeeeaaaeeeeeaaaeees 253 4 1 Installed Documentation cceeeeeee ee eeeeeeeeeeeeeeeeaeaaeeeeeeeeeeeeaea 253 24 Apache HTTP Server Configuration ccccceeeeeeeeeeeeeeeeeeeeeaeaaeeeeeeeeeeeeaas 255 1 Basic S tnGS sicezoccsssussesendunoesbenisoecestexeeesanliteresdan ceed anaaveesstegereiesiaweesens 256 2 Default Settings 2 2 cece ce eeee cece ae ence eeeeeeeeceaeaaaaeeeeeeeeseaaaaaaaaeeeeeeseaeaaaaees 258 2 1 Site Configuration
29. e Automatic CPU detection to take advantage of certain CPU optimizations 4 RAID Levels and Linear Support RAID supports various configurations including levels 0 1 4 5 and linear These RAID types are defined as follows e Level 0O RAID level 0 often called striping is a performance oriented striped data 1A hot swap chassis allows you to remove a hard drive without having to power down your system 96 RAID Levels and Linear Support mapping technique This means the data being written to the array is broken down into strips and written across the member disks of the array allowing high I O performance at low inherent cost but provides no redundancy The storage capacity of a level 0 array is equal to the total capacity of the member disks in a Hardware RAID or the total capacity of member partitions in a Software RAID Level 1 RAID level 1 or mirroring has been used longer than any other form of RAID Level 1 provides redundancy by writing identical data to each member disk of the array leaving a mirrored copy on each disk Mirroring remains popular due to its simplicity and high level of data availability Level 1 operates with two or more disks that may use parallel access for high data transfer rates when reading but more commonly operate independently to provide high I O transaction rates Level 1 provides very good data reliability and improves performance for read intensive applications but at a relativ
30. ldapbasedn If you specified either enableldap Or enableldapauth use this option to specify the DN in your LDAP directory tree under which user information is stored This option is set in the etc ldap conf file enableldaptls Use TLS Transport Layer Security lookups This option allows LDAP to send encrypted usernames and passwords to an LDAP server before authentication enablekrb5 Use Kerberos 5 for authenticating users Kerberos itself does not know about home directories UIDs or shells If you enable Kerberos you must make users accounts known to this workstation by enabling LDAP NIS or Hesiod or by using the usr sbin useradd command to make their accounts known to this workstation If you use this option you must have the pam_krb5 package installed krb5realm The Kerberos 5 realm to which your workstation belongs krb5kdc The KDC or KDCs that serve requests for the realm If you have multiple KDCs in your realm separate their names with commas krb5adminserver The KDC in your realm that is also running kadmind This server handles password changing and other administrative requests This server must be run on the master KDC if you have more than one KDC Kickstart Options enablehesiod Enable Hesiod support for looking up user home directories UIDs and shells More information on setting up and using Hesiod on your network is in usr share doc glibc 2 x x README hesiod whi
31. or protocol restricted most proxies work with TCP connected services only Application services cannot run behind a proxy so your application servers must use a separate form of network security Proxies can become a network bottleneck as all requests and transmissions are passed through one source rather than directly from a client to a remote service Table 18 1 Firewall Types 1 Netfilter and IPTables The Linux kernel features a powerful networking subsystem called Netfilter The Netfilter subsystem provides stateful or stateless packet filtering as well as NAT and IP masquerading services Netfilter also has the ability to mangle IP header information for advanced routing and connection state management Netfilter is controlled using the iptables tool 1 1 IPTables Overview The power and flexibility of Netfilter is implemented using the iptables administration tool a command line tool similar in syntax to its predecessor ipchains A similar syntax does not mean similar implementation however ipchains requires intricate rule sets for filtering source paths filtering destination paths and filtering both source and destination connection ports 190 Basic Firewall Configuration By contrast iptables uses the Netfilter subsystem to enhance network connection inspection and processing iptables features advanced logging pre and post routing actions network address translation and port forwar
32. path to dd imgdriverdisk source nfs host path to img lt partition gt Partition containing the driver disk type File system type for example vfat or ext2 rewall optional This option corresponds to the Firewall Configuration screen in the installation program firewall nabled disabled trust lt device gt port enabled Reject incoming connections that are not in response to outbound requests such as DNS replies or DHCP requests If access to services running on this machine is needed you can choose to allow specific services through the firewall disabled Do not configure any iptables rules Erust Listing a device here such as eth0O allows all traffic coming from that device to go through the firewall To list more than one device use trust ethO trust eth1 Do NOT use a comma separated format such as trust eth0 ethl 10 Kickstart Options lt incoming gt Replace with one or more of the following to allow the specified services through the firewall ssh e telnet snitp http s ftp p0rt You can specify that ports be allowed through the firewall using the port protocol format For example to allow IMAP access through your firewall specify imap tcp Numeric ports can also be specified explicitly for example to allow UDP packets on port 1234 through specify 1234 udp To specify multiple ports separate them by co
33. wom cello Cromeclosy 1 LO S in aiceeln jon The output is similar to the following etc cron daily etc cron hourly etc cron monthly etc cron weekly etc crontab usr bin run parts These are just a few examples As you use it you will find many more uses for RPM 5 Additional Resources RPM is an extremely complex utility with many options and methods for querying installing upgrading and removing packages Refer to the following resources to learn more about RPM 5 1 Installed Documentation rpm help This command displays a quick reference of RPM parameters man rpm The RPM man page gives more detail about RPM parameters than the rpm help command 5 2 Useful Websites htto www rpm org The RPM website e http vwww redhat com mailman listinfo rom list The RPM mailing list is archived here To subscribe send mail to lt rpm list request redhat com gt with the word subscribe in the subject line 5 3 Related Books 153 Chapter 15 Package Managemen Red Hat RPM Guide by Eric Foster Johnson Wiley John amp Sons Incorporated This book is a comprehensive guide to RPM from installing package to building RPMs 154 Chapter 16 Red Hat Network Red Hat Network is an Internet solution for managing one or more Red Hat Enterprise Linux systems All Security Alerts Bug Fix Alerts and Enhancement Alerts collectively known as Errata Alerts can be
34. 2 Per group 3 Via the effective rights mask 4 For users not in the user group for the file The set fac1 utility sets ACLs for files and directories Use the m option to add or modify the ACL of a file or directory setfacl m lt rules gt lt files gt Rules lt rules gt must be specified in the following formats Multiple rules can be specified in the same command if they are separated by commas u lt uid gt lt perms gt Sets the access ACL for a user The user name or UID may be specified The user may be any valid user on the system g lt gid gt lt perms gt Sets the access ACL for a group The group name or GID may be specified The group may be any valid group on the system m lt perms gt Sets the effective rights mask The mask is the union of all permissions of the owning group and all of the user and group entries o lt perms gt Sets the access ACL for users other than the ones in the group for the file White space is ignored Permissions lt perms gt must be a combination of the characters r w and x for read write and execute If a file or directory already has an ACL and the set facl command is used the additional rules are added to the existing ACL or the existing rule is modified For example to give read and write permissions to user andrius 134 Setting Default ACLs setfacl m u andrius rw project somefile To remove all the permissions for a user group or other
35. CA SSL handles the encrypted communications as well as the mutual authentication between browsers and your secure server The CA approved digital certificate provides authentication for your secure server the CA puts its reputation behind its certification of your organization s identity When your browser is communicating using SSL encryption the https prefix is used at the beginning of the Uniform Resource Locator URL in the navigation bar Encryption depends upon the use of keys think of them as secret encoder decoder rings in data format In conventional or symmetric cryptography both ends of the transaction have the same key which they use to decode each other s transmissions In public or asymmetric cryptography two keys co exist a public key and a private key A person or an organization keeps their private key a secret and publishes their public key Data encoded with the public key can only be decoded with the private key data encoded with the private key can only be decoded with the public key To set up your secure server use public cryptography to create a public and private key pair In most cases you send your certificate request including your public key proof of your company s identity and payment to a CA The CA verifies the certificate request and your identity and then sends back a certificate for your secure server A secure server uses a Certificate to identify itself to Web browsers You can generate your
36. Chapter 25 Apache HTTP Secur The openss1 package contains the OpenSSL toolkit The OpenSSL toolkit implements the SSL and TLS protocols and also includes a general purpose cryptography library Additionally other software packages provide certain security functionalities but are not required by the secure server to function httpd devel The httpd devel package contains the Apache HTTP Server include files header files and the APXS utility You need all of these if you intend to load any extra modules other than the modules provided with this product Refer to the Red Hat Enterprise Linux Reference Guide for more information on loading modules onto your secure server using Apache s dynamic shared object DSO functionality If you do not intend to load other modules onto your Apache HTTP Server you do not need to install this package OpenSSH packages The OpenSSH packages provide the OpenSSH set of network connectivity tools for logging into and executing commands on a remote machine OpenSSH tools encrypt all traffic including passwords so you can avoid eavesdropping connection hijacking and other attacks on the communications between your machine and the remote machine The openssh package includes core files needed by both the OpenSSH client programs and the OpenSSH server The openssh package also contains scp a secure replacement for rcp for securely copying files between machines The openssh askpass package
37. IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY Someone could be eavesdropping on you right now man in the middle attack 213 Chapter 20 OpenSSH It is also possible that the RSA host key has just been changed If you want to keep the host keys generated for the system backup the etc ssh ssh_host key files and restore them after the reinstall This process retains the system s identity and when clients try to connect to the system after the reinstall they will not receive the warning message 3 Configuring an OpenSSH Client To connect to an OpenSSH server from a client machine you must have the openssh clients and openssh packages installed on the client machine 3 1 Using the ss Command The ssh command is a secure replacement for the rlogin rsh and telnet commands It allows you to log in to a remote machine as well as execute commands on a remote machine Logging in to a remote machine with ssh is similar to using telnet To log in to a remote machine named penguin example net type the following command at a shell prompt ssh penguin example net The first time you ssh to a remote machine you will see a message similar to the following The authenticity of host penguin example net can t be established DSATkey Fingerprint uso 4 68S ansasbe sts Jab Ol Sa po i0myssie2 leer Are you sure you want to continue connecting yes no Type yes to continue
38. If it is a local ext3 file system it can mounted with the following command mount t ext3 o acl lt device name gt lt partition gt For example mount t ext3 o acl dev VolGroup00 LogVol02 work Alternatively if the partition is listed in the etc fstab file the entry for the partition can include the acl option LABEL work work ext3 acl il 2 If an ext3 file system is accessed via Samba and ACLs have been enabled for it the ACLs are recognized because Samba has been compiled with the with acl support option No special flags are required when accessing or mounting a Samba share 1 1 NFS By default if the file system being exported by an NFS server supports ACLs and the NFS client can read ACLs ACLs are utilized by the client system To disable ACLs on NFS shares when configuring the server include the no_ac1 option in the etc exports file To disable ACLs on an NFS share when mounting it on a client mount it with the no_ac1 option via the command line or the etc fstab file 133 Chapter 14 Access Control Lists 2 Setting Access ACLs There are two types of ACLs access ACLs and default ACLs An access ACL is the access control list for a specific file or directory A default ACL can only be associated with a directory if a file within the directory does not have an access ACL it uses the rules of the default ACL for the directory Default ACLs are optional ACLs can be configured 1 Per user
39. Red Hat Enterprise Linux contains the following kernel packages some may not apply to your architecture kernel Contains the kernel and the following key features e Uniprocessor support for x86 and Athlon systems can be run on a multi processor system but only one processor is utilized e Multi processor support for all other architectures e For x86 systems only the first 4 GB of RAM is used use the kernel hugemem package for x86 systems with over 4 GB of RAM kernel devel Contains the kernel headers and makefiles sufficient to build modules 361 Chapter 36 Manually Upgradin against the kernel package kernel hugemem only for i686 systems In addition to the options enabled for the kernel package the key configuration options are as follows e Support for more than 4 GB of RAM up to 64 GB for x86 Note kernel hugemem is required for memory configurations higher than 16 GB e PAE Physical Address Extension or 3 level paging on x86 processors that support PAE e Support for multiple processors e 4GB 4GB split 4GB of virtual address space for the kernel and almost 4GB for each user process on x86 systems kernel hugemem devel Contains the kernel headers and makefiles sufficient to build modules against the kernel hugemem package kernel smp Contains the kernel for multi processor systems The following are the key features Multi processor support Support
40. To verify that it was created use the command 1s 1 boot to make sure the boot vmlinitrd lt kernel version gt file was created the version should match the version of the kernel just installed The next step is to verify that the boot loader has been configured to boot the new kernel Refer to Section 6 Verifying the Boot Loader for details 6 Verifying the Boot Loader The kernel RPM package configures the boot loader to boot the newly installed kernel except for IBM eServer iSeries systems However it does not configure the boot loader to boot the new kernel by default It is always a good idea to confirm that the boot loader has been configured correctly This is a crucial step If the boot loader is configured incorrectly the system does not boot into Red Hat Enterprise Linux properly If this happens boot the system with the boot media created earlier and try configuring the boot loader again 6 1 x86 Systems All x86 systems use GRUB as the boot loader which includes all AMD64 systems 6 1 1 GRUB Confirm that the file boot grub grub conf contains a title section with the same version as the kernel package just installed if the kernel smp Or kernel hugemem package was installed a section exists for it as well Note that you do not have to rerun grub after making changes to this file NOTICE You have a boot partition This means that all kernel and initrd paths are relative to boot eg root ray k
41. a rule to forward all incoming HTTP requests so that destination NAT routing is possible To do this use the following command root myServer iptables A FORWARD i eth0 p tcp dport 80 d 172 31 V2 WeCae 1 This rule forwards all incoming HTTP requests from the firewall to the intended destination the Apache HTTP Server behind the firewall 5 3 DMZs and IPTables You can create iptables rules to route traffic to certain machines such as a dedicated HTTP or FTP server in a demilitarized zone DMZ A DMZ is a special local subnetwork dedicated to providing services on a public carrier such as the Internet For example to set a rule for routing incoming HTTP requests to a dedicated HTTP server at 10 0 4 2 outside of the 192 168 1 0 24 range of the LAN NAT uses the PREROUTING table to forward the packets to the appropriate destination root myServer iptables t nat A PREROUTING i eth0 p tcp dport 80 DNAT to Cestlnatiom 10 04 2380 With this command all HTTP connections to port 80 from outside of the LAN are routed to the HTTP server on a network separate from the rest of the internal network This form of network segmentation can prove safer than allowing HTTP connections to a machine on the network If the HTTP server is configured to accept secure connections then port 443 must be forwarded as well 6 Malicious Software and Spoofed IP Addresses More elaborate rules can be created that
42. be installed Y VolGroup00 17152 LogVol02 swap y 1024 If you do not know how to LogVol00 ext3 y 10016 partition your system or if you LogVol01 home ext3 s 5024 need dived sie aii 7 Hard Drives manual partitioning tools refer to the nan cchmnnian 7 heen dev sdal boot ext3 y 102 1 B If you used automatic dev sda2 VolGroup00 LVMPV 8574 14 1106 partitioning you can either V dev sdb accept the current partition dev sdb1 VolGroup00 LVMPV 8676 1 1106 settings click Next or modify the setup using the manual partitioning tool If you are manually partitioning your system you can see your current hard drive s and partitions displayed below Use Figure 8 10 Final Manual Configuration 94 Chapier 9 Redundant Array of Independent Disks RAID 1 What is RAID The basic idea behind RAID is to combine multiple small inexpensive disk drives into an array to accomplish performance or redundancy goals not attainable with one large and expensive drive This array of drives appears to the computer as a single logical storage unit or drive RAID is a method in which information is spread across several disks RAID uses techniques such as disk striping RAID Level 0 disk mirroring RAID level 1 and disk striping with parity RAID Level 5 to achieve redundancy lower latency and or to increase bandwidth for reading or writing to disks and to maximize the ability to recover from hard d
43. directories on an hourly daily weekly or monthly basis respectively The files in these directories should be shell scripts If a cron task is required to be executed on a schedule other than hourly daily weekly or monthly it can be added to the etc cron d directory All files in this directory use the same syntax as etc crontab Refer to Example 34 1 Crontab Examples for examples record the memory usage of the system every monday at 3 30AM in the file tmp meminfo 30 3 mon cat proc meminfo gt gt tmp meminfo 350 Controlling Access to Cron run custom script the first day of every month at 4 10AM 10 418 e coot seripes oackula sia Example 34 1 Crontab Examples Users other than root can configure cron tasks by using the crontab utility All user defined crontabs are stored in the var spool cron directory and are executed using the usernames of the users that created them To create a crontab as a user login as that user and type the command crontab e to edit the user s crontab using the editor specified by the vrsuat or EDITOR environment variable The file uses the same format as etc crontab When the changes to the crontab are saved the crontab is stored according to username and written to the file var spool cron username The cron daemon checks the etc crontab file the etc cron d directory and the var spool cron directory every minute for any changes If any changes are foun
44. ext3 LVM PV software RAID software RAID software RAID software RAID 8512 1024 1024 5024 101 944 8573 75 102 8574 102 8574 Figure 10 9 Final Sample RAID With LVM Configuration You can continue with your installation process Refer to the Red Hat Enterprise Linux Installation Guide for further instructions 108 Chapter 11 Swap space in Linux is used when the amount of physical memory RAM is full If the system needs more memory resources and the RAM is full inactive pages in memory are moved to the swap space While swap space can help machines with a small amount of RAM it should not be considered a replacement for more RAM Swap space is located on hard drives which have a slower access time than physical memory Swap space can be a dedicated swap partition recommended a swap file or a combination of swap partitions and swap files The size of your swap should be equal to twice your computer s physical RAM for up to 2 GB of physical RAM For physical RAM above 2 GB the size of your swap should be equal to the amount of physical RAM above 2 GB The size of your swap should never be less than 32 MB Using this basic formula a system with 2 GB of physical RAM would have 4 GB of swap while one with 3 GB of physical RAM would have 5 GB of swap Note Unfortunately deciding on the amount of swap to allocate to Red Hat Enterprise Linux is more of an art than a science
45. geniusnmps 2 geniusprops 2 geniusscrollps 2 geniusscrollps 2 thinking thinkingps 2 logitech logitechec logibm logimman logimmanps 2 logimman logimman ps 2 logimmusb microsoft msnew msintelli msintellips 2 msintelliusb msbm mousesystems mmseries mmhittab sun none This list can also be found in the usr lib python2 2 site packages rhpl mouse py file which is part of the rhp1 package If the mouse command is given without any arguments or it is omitted the installation program attempts to automatically detect the mouse This procedure works for most modern mice network optional Configures network information for the system If the kickstart installation does not require networking in other words it is not installed over NFS HTTP or FTP networking is not configured for the system If the installation does require networking and network information is not provided in the kickstart file the installation program assumes that the installation should be done over ethO via a dynamic IP address BOOTP DHCP and configures the final installed system to determine its IP address dynamically The network option configures networking information for kickstart installations via a network as well as for the installed system bootproto One of dhcp bootp Or static It defaults to dhcp bootp and dhcp are treated the same The DHCP method uses a DHCP server system to obtain its networking configuration As you
46. hdal or sdc3 Format partition Figure 2 6 Creating a Software RAID Partition Repeat these steps to create as many partitions as needed for your RAID setup All of your partitions do not have to be RAID partitions After creating all the partitions needed to form a RAID device follow these steps 43 Chapter 2 Kickstart Configurator 1 Click the RAID button 2 Select Create a RAID device 3 Select a mount point file system type RAID device name RAID level RAID members number of spares for the software RAID device and whether to format the RAID device Mount Point home File System Type ext3 RAID Device mdo RAID Level raid 01 Raid Members raid 02 Number of spares 1 Format RAID device Ja Figure 2 7 Creating a Software RAID Device 4 Click OK to add the device to the list 5 Network Configuration 44 Authentication File Help Basic Configuration Network Configuration Installation Method Device Network Type Add Network Device Boot Loader Options Edit Network Device Partition Information Network Configuration Delete Network D evice Authentication Firewall Configuration Display Configuration Package Selection Pre Installation Script Post Installation Script Figure 2 8 Network Configuration If the system to be installed via kickstart does not have an Ethernet card do not configure one on the Network Conf
47. host apex option host name apex example com hardware ethernet 00 A0 78 8E 9E AA iieclaclolieass IL 2 eis il Example 23 5 Static IP Address using DHCP Tip The sample configuration file provided can be used as a starting point and custom configuration options can be added to it To copy it to the proper location use the following command cp usr share doc dhcp lt version number gt dhcpd conf sample etc dhcpd conf where lt version number gt is the DHCP version number For a complete list of option statements and what they do refer to the dhcp options man page 2 2 Lease Database On the DHCP server the file var lib dhcp dhcpd leases stores the DHCP client lease database This file should not be modified by hand DHCP lease information for each recently assigned IP address is automatically stored in the lease database The information includes the length of the lease to whom the IP address has been assigned the start and end dates for the lease and the MAC address of the network interface card that was used to retrieve the lease 249 Chapter 23 Dynamic Host Conf All times in the lease database are in Greenwich Mean Time GMT not local time The lease database is recreated from time to time so that it is not too large First all known leases are saved in a temporary lease database The dhcpd leases file is renamed dhcpd leases and the temporary lease database is written
48. in addition to the partitions for the RAID device Select the partitions for the RAID device and the partition s for the spare s 10After clicking OK the RAID device appears in the Drive Summary list 11 Repeat this chapter s entire process for configuring additional partitions devices and mount points such as the root partition nhome or Swap After completing the entire configuration the figure as shown in Figure 10 8 Final Sample RAID Configuration resembles the default configuration except for the use of RAID 106 Creating the RAID Devices and Mount Disk Setup Choose where you would like Red Hat Enterprise Linux AS to be installed If you do not know how to partition your system or if you need help with using the manual partitioning tools refer to the product documentation If you used automatic partitioning you can either accept the current partition settings click Next or modify the setup using the manual partitioning tool If you are manually partitioning your system you can see your current hard drive s and partitions displayed below Use Hide Help Release Notes Figure 10 8 Final Sample RAID Configuration Ej New Edit Delete Reset Mount Point Size VY RAID Devices dev mdO dev md1 dev md2 V Hard Drives VY dev sda dev sdal dev sda2 dev sda3 V dev sdb dev sdb1 dev sdb2 dev sdb3 boot dev md0 dev md1 de
49. modified are preserved during reinstallation Pristine Sources A crucial design goal was to allow the use of pristine software sources as distributed by the original authors of the software With RPM you have the pristine sources along with any patches that were used plus complete build instructions This is an important advantage for several reasons For instance if a new version of a program comes out you do not necessarily have to start from scratch to get it to compile You can look at the patch to see what you might need to do All the compiled in defaults and all of the changes that were made to get the software to build properly are easily visible using this technique The goal of keeping sources pristine may only seem important for developers but it results in higher quality software for end users too 2 Using RPM RPM has five basic modes of operation not counting package building installing uninstalling upgrading querying and verifying This section contains an overview of each mode For complete details and options try rpm help or refer to Section 5 Additional Resources for more information on RPM 2 1 Finding RPM Packages Before using an RPM you must know where to find them An Internet search returns many RPM repositories but if you are looking for RPM packages built by Red Hat they can be found at the following locations e The Red Hat Enterprise Linux CD ROMs e The Red Hat Errata Page availabl
50. 13 raid 23 raid usr fstyp xt3 device md3 level RAID1 raid 14 raid 24 raid pv 01l fstyp sat 3 device md4 level RAID1 raid 15 raid 25 LVM configuration so that we can resize var and usr local later volgroup sysvg pv 01 logvol var vgname sysvg size 8000 name var logvol var freespac vgname sysvg size 8000 name freespacetous logvol usr local vgname sysvg size 1 grow name usrlocal This advanced example implements LVM over RAID as well as the ability to resize various directories for future growth 5 Package Selection Use the packages command to begin a kickstart file section that lists the packages you would like to install this is for installations only as package selection during upgrades is not supported Packages can be specified by group or by individual package name The installation program defines several groups that contain related packages Refer to the RedHat base comps xm1 file on the first Red Hat Enterprise Linux CD ROM for a list of groups Each group has an id user visibility value name description and package list In the package list the packages marked as mandatory are always installed if the group is selected the packages marked default are selected by default if the group is selected and the packages marked optional must be specifically selected even if the group is selected to be installed 24 Pre installation Script In most cases it is only nec
51. 184 Device Aliases boot time title Red Hat Enterprise Linux 2 6 9 5 EL root hd0 0 kernel vmlinuz 2 6 9 5 EL ro root dev VolGroup00 LogVol00 netprofile lt profilename gt rhgb quiet initrd initrd 2 6 9 5 EL img To switch profiles after the system has booted go to Applications the main menu on the panel gt System Tools gt Network Device Control or type the command system control network to select a profile and activate it The activate profile section only appears in the Network Device Control interface if more than the default Common interface exists Alternatively execute the following command to enable a profile replace lt profilename gt with the name of the profile system config network cmd profile lt profilename gt activate 11 Device Aliases Device aliases are virtual devices associated with the same physical hardware but they can be activated at the same time to have different IP addresses They are commonly represented as the device name followed by a colon and a number for example eth0 1 They are useful if you want to have multiple IP addresses for a system that only has one network card After configuring the Ethernet device such as etho to use a static IP address DHCP does not work with aliases go to the Devices tab and click New Select the Ethernet card to configure with an alias set the static IP address for the alias and click Apply to create it Since a dev
52. 324 users see user configuration etc passwd 330 additional resources 335 installed documentation 335 introducing 319 standard 330 tools for management of User Manager 324 useradd 324 UID 319 V VeriSign using existing certificate 279 video card settings for dual head 317 settings for X 316 volume group 79 volume groups 90 W Windows file and print sharing 231 Windows 2000 connecting to shares using Samba 237 Windows 98 connecting to shares using Samba 237 Windows ME connecting to shares using Samba 237 Windows NT 4 0 connecting to shares using Samba 237 Windows XP connecting to shares using Samba 237 X X Configuration Tool display settings 315 dual head display settings 317 hardware settings 316 X Window System 415 Index configuration 315 xDSL connection see network configuration xinetd 207 Y ypbind 290 416
53. 6 9 5 EL i686 rpm The next step is to verify that the initial RAM disk image has been created Refer to Section 5 Verifying the Initial RAM Disk Image for details 5 Verifying the Initial RAM Disk Image If the system uses the ext3 file system a SCSI controller or uses labels to reference partitions in etc fstab an initial RAM disk is needed The initial RAM disk allows a modular kernel to have access to modules that it might need to boot from before the kernel has access to the device where the modules normally reside On the Red Hat Enterprise Linux architectures other than IBM eServer iSeries the initial RAM disk can be created with the mkinitrd command However this step is performed automatically if the kernel and its associated packages are installed or upgraded from the RPM packages distributed by Red Hat Inc thus it does not need to be executed manually To verify that it was 365 Chapter 36 Manually Upgradin created use the command 1s 1 boot to make sure the initrd lt version gt img file was created the version should match the version of the kernel just installed On iSeries systems the initial RAM disk file and vm1inux file are combined into one file which is created with the addRamDisk command This step is performed automatically if the kernel and its associated packages are installed or upgraded from the RPM packages distributed by Red Hat Inc thus it does not need to be executed manually
54. After verifying that do the following steps 1 Create a link from the name of your application such as our sample foo program to the usr bin consolehelper application cd usr binln s consolehelper foo 2 Create the file etc security console apps foo touch etc security console apps foo 3 Create a PAM configuration file for the foo service in etc pam d An easy way to do this is to start with a copy of the halt service s PAM configuration file and then modify the file if you want to change the behavior cp etc pam d halt etc pam d foo Now when usr bin foo Is executed consolehelper is called which authenticates the user with the help of usr sbin userhelper To authenticate the user consolehelper asks for the user s password if etc pam d foo is a copy of etc pam d halt otherwise it does precisely what is specified in etc pam d foo and then runs usr sbin foo with root permissions In the PAM configuration file an application can be configured to use the pam_timestamp module to remember or cache a successful authentication attempt When an application is started and proper authentication is provided the root password a timestamp file is created By default a successful authentication is cached for five minutes During this time any other application that is configured to use pam_timestamp and run from the same session is automatically authenticated for the user the user does not have to enter the roo
55. Configuration Tool ntsysv or chkconfig For a list of network services controlled by xinetd review the contents of the etc xinetd d directory with the command 1s etc xinetd d 3 Services Configuration Tool The Services Configuration Tool is a graphical application developed by Red Hat to configure which SysV services in the etc rc d init d directory are started at boot time for runlevels 3 4 and 5 and which xinetd services are enabled It also allows you to start stop and restart SysV services as well as restart xinetd To start the Services Configuration Tool from the desktop go to the Main Menu Button on the Panel gt System Settings gt Server Settings gt Services or type the command system config services ata shell prompt for example in an XTerm or a GNOME terminal 207 Chapter 19 Controlling Acces File Actions Edit Runlevel Help gt O AJU Start Stop Restart Save Revert Currently Running in Runlevel 5 Editing Runlevel 5 a Description Startup shutdown script for the Common UNIX cups Printing System CUPS cups Ipd K crond daytime daytime udp dbskkd cdb dhcpd dhcrelay echo echo udp Status eklogin cupsd pid 1961 is running finger firstboot gpm gssftp hpoj httpd identd O O O 0 0O 0O O O O O O E 0 a 0O O Figure 19 1 Services Configuration Tool The Services Configuration Tool displays the current runlevel as well as the runl
56. D 8 x x New Edit Copy Delete Activate Deactivate Devices Hardase Pec OS Hosts O You may configure network devices associated with ma co physical hardware here Multiple logical devices can be di 3 associated with a single piece of hardware Presume Tome ware e A Inactive ine IpppO Provider Chapter 17 Network Configuration Figure 17 5 ISDN Device 4 Establishing a Modem Connection A modem can be used to configure an Internet connection over an active phone line An Internet Service Provider ISP account also called a dial up account is required To add a modem connection follow these steps 1 Click the Devices tab 2 Click the New button on the toolbar 3 Select Modem connection from the Device Type list and click Forward 4 lf there is a modem already configured in the hardware list on the Hardware tab the Network Administration Tool assumes you want to use it to establish a modem connection If there are no modems already configured it tries to detect any modems in the system This probe might take a while If a modem is not found a message is displayed to warn you that the settings shown are not values found from the probe 5 After probing the window in Figure 17 6 Modem Settings appears Select Modem Modem Properties Modem Device dev ttySo Baud Rate 57600 Flow Control Hardware CRTSCTS Use touch tone dialing Figure 17 6 Modem
57. FTP server requires a username and password specify them as well HTTP Choose this option to install or upgrade from an HTTP server In the text field for the HTTP server enter the fully qualified domain name or IP address For the HTTP directory enter the name of the HTTP directory that contains the RedHat directory For example if the HTTP server contains the directory mirrors redhat i386 RedHat enter mirrors redhat i386 for the HTTP directory Hard Drive Choose this option to install or upgrade from a hard drive Hard drive installations require the use of ISO or CD ROM images Be sure to verify that the ISO images are intact before you start the installation To verify them use an md5sum program as well as the linux mediacheck boot option as discussed in the Red Hat Enterprise Linux Installation Guide Enter the hard drive partition that contains the ISO images for example dev hda1 in the Hard Drive Partition text box Enter the directory that contains the ISO images in the Hard Drive Directory text box 3 Boot Loader Options 38 Boot Loader Options File Help Basic Configuration Boot Loader Options required Installation Method Install new boot loader A O i Boot Loader Options Do not install a boot loader w Upgrade existing boot loader Partition Information ne 3E a Network Configuration GRUB Options Authentication C Use GRUB password Firewall Configuration ean Display Configuration
58. Full multi user mode e 4 Not used user definable 5 Full multi user mode with an X based login screen e 6 Reboot If you use a text login screen you are operating in runlevel 3 If you use a graphical login screen you are operating in runlevel 5 The default runlevel can be changed by modifying the etc inittab file which contains a line near the top of the file similar to the following Ice Ss ainaiecleraw lic Change the number in this line to the desired runlevel The change does not take effect until you reboot the system To change the runlevel immediately use the command telinit followed by the runlevel number You must be root to use this command The telinit command does not change the etc inittab file it only changes the runlevel currently running When the system is rebooted it continues to boot the runlevel as specified in etc inittab 2 TCP Wrappers Many UNIX system administrators are accustomed to using TCP wrappers to manage access to certain network services Any network services managed by xinetd as well as any program with built in support for 1ibwrap can use TCP wrappers to manage access xinetd can use 206 xinetd the etc hosts allow and etc hosts deny files to configure access to system services As the names imply hosts allow contains a list of rules that allow clients to access the network services controlled by xinetd and hosts deny contains rules to deny access The hosts
59. IDE Controller 00 0f 2 USB Controller ServerWorks OSB4 CSB5 OHCI USB Controller rev 04 01 03 0 SCSI storege controllers Adaptec AIC 7892P UlGO w reyr O2 01 05 0 RAID bus controller IBM ServeRAID Controller The 1spci is also useful to determine the network card in your system if you do not know the manufacturer or model number 5 Additional Resources To learn more about gathering system information refer to the following resources 5 1 Installed Documentation ps help Displays a list of options that can be used with ps top manual page Type man top to learn more about top and its many options free manual page type man free to learn more about free and its many options af manual page Type man df to learn more about the af command and its many options du manual page Type man du to learn more about the du command and its many options e lspci manual page Type man lspci to learn more about the 1spci command and its many options e proc directory The contents of the proc directory can also be used to gather more detailed system information 386 Chapter 40 OProfile OProfile is a low overhead system wide performance monitoring tool It uses the performance monitoring hardware on the processor to retrieve information about the kernel and executables on the system such as when memory is referenced the number of L2 cache requests and the number of hardware interrupts re
60. If you need more than four partitions you can have three primary partitions one extended partition and multiple logical partitions within the extended For an overview of disk partitions refer to the appendix An Introduction to Disk Partitions in the Red Hat Enterprise Linux Installation Guide For example to create a primary partition with an ext3 file system from 1024 megabytes until 2048 megabytes on a hard drive type the following command mkpart primary ext3 1024 2048 Tip If you use the mkpart fs command instead the file system is created after the partition is created However partea does not support creating an ext3 file system Thus if you wish to create an ext3 file system use mkpart and create the file system with the mkfs command as described later mkpart fs works for file system type linux swap The changes start taking place as soon as you press Enter so review the command before executing to it After creating the partition use the print command to confirm that it is in the partition table with the correct partition type file system type and size Also remember the minor number of the new partition so that you can label it You should also view the output of cat PrOCPA n AEN to make sure the kernel recognizes the new partition 1 2 2 Formating the Partition The partition still does not have a file system Create the file system sbin mkfs t ext3 dev sda6 Warning 118 Removing a Partition
61. Linux as the Red Hat Enterprise Linux disk from which you booted If you used a boot CD ROM or other media to start rescue mode the installation tree must be from the same tree from which the media was created For more information about how to setup an installation tree on a hard drive NFS server FTP server or HTTP server refer to the earlier section of this guide If you select a rescue image that does not require a network connection you are asked whether or not you want to establish a network connection A network connection is useful if you need to backup files to a different computer or install some RPM packages from a shared network 1 Refer to the earlier sections of this guide for more details 68 Booting into Rescue Mode location for example The following message is displayed The rescue environment will now attempt to find your Linux installation and mount it under the directory mnt sysimage You can then make any changes required to your system If you want to proceed with this step choose Continue You can also choose to mount your file systems read only instead of read write by choosing Read only If for some reason this process fails you can choose Skip and this step will be skipped and you will go directly to a command shell If you select Continue it attempts to mount your file system under the directory mnt sysimage If it fails to mount a partition it notifies you If you select Read Only
62. Menu Button gt System Settings gt Server Settings gt HTTP or type the command system config httpd at a shell prompt for example in an XTerm or GNOME Terminal The HTTP Configuration Tool allows you to configure the etc httpd conf httpd conf configuration file for the Apache HTTP Server It does not use the old srm conf or access conf configuration files leave them empty Through the graphical interface you can configure directives such as virtual hosts logging attributes and maximum number of connections Only modules provided with Red Hat Enterprise Linux can be configured with the HTTP Configuration Tool If additional modules are installed they can not be configured using this tool An Caution Do not edit the etc httpd conf httpd conf configuration file by hand if you wish to use this tool The HTTP Configuration Tool generates this file after you save your changes and exit the program If you want to add additional modules or configuration options that are not available in HTTP Configuration Tool you cannot use this tool The general steps for configuring the Apache HTTP Server using the HTTP Configuration Tool are as follows 1 Configure the basic settings under the Main tab 2 Click on the Virtual Hosts tab and configure the default settings 255 Chapter 24 Apache HTTP Serve 3 Under the Virtual Hosts tab configure the Default Virtual Host 4 To serve more than one URL or virtua
63. Tasks To use at Or batch the at RPM package must be installed and the ata service must be running To determine if the package is installed use the rpm q at command To determine if the service is running use the command sbin service atd status 2 1 Configuring At Jobs To schedule a one time job at a specific time type the command at time where time is the time to execute the command The argument time can be one of the following HH MM format For example 04 00 specifies 4 00 a m If the time is already past it is executed at the specified time the next day midnight Specifies 12 00 a m noon Specifies 12 00 p m teatime Specifies 4 00 p m month name day year format For example January 15 2002 specifies the 15th day of January in the year 2002 The year is optional MMDDYY MM DD YY or MM DD YY formats For example 011502 for the 15th day of January in the year 2002 now time time is in minutes hours days or weeks For example now 5 days specifies that the command should be executed at the same time five days from now The time must be specified first followed by the optional date For more information about the time format read the usr share doc at lt version gt timespec text file After typing the at command with the time argument the at gt prompt is displayed Type the command to execute press Enter and type Ctrl D Multiple commands can be specified by typing ea
64. The Mail Transport Agent Switcher allows for the selection of either sendmail post fix Of eximas the default MTA for the system The system switch mail RPM package must be installed to use the text based version of the Mail Transport Agent Switcher program If you want to use the graphical version the system switch mail gnome package must also be installed To start the Mail Transport Agent Switcher select Applications the main menu on the panel gt Preferences gt More Preferences gt Mail Transport Agent Switcher or type the command system switch mail at a shell prompt for example in an XTerm or GNOME terminal The program automatically detects if the X Window System is running If it is running the program starts in graphical mode as shown in Figure 38 1 Mail Transport Agent Switcher If X is not detected it starts in text mode To force Mail Transport Agent Switcher to run in text mode use the command system switch mail nox 375 Chapter 38 Mail Transport Ag The Mail Transport Agent Switcher is a tool which enables users to easily switch between various Mail Transport Agent that they have installed Please choose your Mail transport agent Available Mail Transport Agent Sendmail Postfix Exim Figure 38 1 Mail Transport Agent Switcher If you select OK to change the MTA the selected mail daemon is enabled to start at boot time and the unselected mail daemons are disabled
65. Use the Set for CGI Scripts section to set an environment variable that is passed to CGI scripts and SSI pages For example to set the environment variable maxnum to 50 click the Add button inside the Set for CGI Script section as shown in Figure 24 5 Environment Variables and type maxnum in the Environment Variable text field and 50 in the Value to set text field Click OK to add it to the list The Set for CGI Scripts section configures the SetEnv http httpd apache org docs 2 0 mod mod_env html setenv directive Use the Pass to CGI Scripts section to pass the value of an environment variable when the 262 Environment Variables server is first started to CGI scripts To see this environment variable type the command env at a shell prompt Click the Add button inside the Pass to CGI Scripts section and enter the name of the environment variable in the resulting dialog box Click OK to add it to the list The Pass to CGI Scripts section configures the PassEnv http httpd apache org docs 2 0 mod mod_env html passenv directive Pass to CGI Scripts Unset for CGI Scripts Cancel Figure 24 5 Environment Variables To remove an environment variable so that the value is not passed to CGI scripts and SSI pages use the Unset for CGI Scripts section Click Add in the Unset for CGI Scripts section and enter the name of the environment variable to unset Click OK to add it to the list This corresponds to th
66. V dev sdb If you are manually partitioning dev sdb1 VolGroup00 LVMPV 8676 1 1106 your system you can see your current hard drive s and E A partitions displayed below Use Hide RAID device LVM Volume Group members Hide Help Release Notes Figure 8 1 Automatic LVM Configuration With Two SCSI Drives Note If enabling quotas are of interest to you it may be best to modify the automatic configuration to include other mount points such as home or var so that each file system has its own independent quota configuration limits In most cases the default automatic LVM partitioning is sufficient but advanced implementations could warrant modification or manual configuration of the LVM partition tables 84 Manual LVM Partitioning Note If you anticipate future memory upgrades leaving some free space in the volume group would allow for easy future expansion of the swap space logical volume on the system in which case the automatic LVM configuration should be modified to leave available space for future growth 2 Manual LVM Partitioning The following section explains how to manually configure LVM for Red Hat Enterprise Linux Because there are numerous ways to manually configure a system with LVM the following example is similar to the default configuration done in Section 1 Automatic Partitioning On the Disk Partitioning Setup screen select M
67. Winbind Support Configure Winbind Use Shadow Passwords Use MD5 Passwords X Cancel 2 OK Figure 26 2 Authentication The following explains what each option configures Enable Kerberos Support Select this option to enable Kerberos authentication Click the Configure Kerberos button to configure e Realm Configure the realm for the Kerberos server The realm is the network that uses Kerberos composed of one or more KDCs and a potentially large number of clients e KDC Define the Key Distribution Center KDC which is the server that issues Kerberos tickets e Admin Servers Specify the administration server s running kadmind The krb5 libs and krb5 workstation packages must be installed for this option to work 291 Chapter 26 Authentication Co Refer to the Red Hat Enterprise Linux Reference Guide for more information on Kerberos Enable LDAP Support Select this option to have standard PAM enabled applications use LDAP for authentication Click the Configure LDAP button to specify the following e Use TLS to encrypt connections Use Transport Layer Security to encrypt passwords sent to the LDAP server e LDAP Search Base DN Retrieve user information by its Distinguished Name DN e LDAP Server Specify the IP address of the LDAP server The openldap clients package must be installed for this option to work Refer to the Red Hat Enterprise
68. a secure interactive FTP session It is similar to ftp except that it uses a secure encrypted connection The general syntax is sftp username hostname com Once authenticated you can use a set of commands similar to those used by FTP Refer to the sftp man page for a list of these commands To read the man page execute the command man sftp ata shell prompt The sftp utility is only available in OpenSSH version 2 5 0p1 and higher 3 4 Generating Key Pairs If you do not want to enter your password every time you use ssh scp Or sftp to connect to a remote machine you can generate an authorization key pair Keys must be generated for each user To generate keys for a user use the following steps as the user who wants to connect to remote machines If you complete the steps as root only root will be able to use the keys Starting with OpenSSH version 3 0 ssh authorized_keys2 ssh known_hosts2 and etc ssh_known_hosts2 are obsolete SSH Protocol 1 and 2 share the ssh authorized_keys ssh known_hosts and etc ssh ssh_known_hosts files Red Hat Enterprise Linux 5 0 0 uses SSH Protocol 2 and RSA keys by default Tip If you reinstall and want to save your generated key pair backup the ssh directory in your home directory After reinstalling copy this directory back to your home directory This process can be done for all users on your system including root 3 4 1 Generating an RSA Key Pair for Version 2 Use the f
69. and Cancel buttons use the Tab key A signifies that a service is set to on Pressing the F1 key displays a short description of the selected service Warning Services managed by xineta are immediately affected by ntsysv For all other services changes do not take effect immediately You must stop or start the individual service with the command service daemon stop In the previous example replace daemon with the name of the service you want to stop for example httpd Replace stop with start or restart to start or restart the service 5 chkconfig The chkconfig command can also be used to activate and deactivate services The chkconfig list command displays a list of system services and whether they are started on or stopped off in runlevels 0 6 At the end of the list is a section for the services managed by xinetd If the chkconfig list command is used to query a service managed by xinetd it displays whether the xinetd service is enabled on or disabled off For example the command chkconfig list finger returns the following output finger on As shown finger is enabled as an xinetd service If xinetd is running finger is enabled If you use chkconfig list to query a service in etc rc d service s settings for each runlevel are displayed For example the command chkconfig list httpd returns the following output 210 Additional Resources httpd ORTONE OTE 20m 3 0n 4 on SRON GIOT chkconf
70. and appears to the host as a single disk RAID controllers also come in the form of cards that act like a SCSI controller to the operating system but handle all of the actual drive communications themselves In these cases you plug the drives into the RAID controller just like you would a SCSI controller but then you add them to the RAID controller s configuration and the operating system never knows the difference 3 2 Software RAID Software RAID implements the various RAID levels in the kernel disk block device code It offers the cheapest possible solution as expensive disk controller cards or hot swap chassis are not required Software RAID also works with cheaper IDE disks as well as SCSI disks With today s fast CPUs Software RAID performance can excel against Hardware RAID The MD driver in the Linux kernel is an example of a RAID solution that is completely hardware independent The performance of a software based array is dependent on the server CPU performance and load For information on configuring Software RAID during installation refer to the Chapter 10 Software RAID Configuration For those interested in learning more about what Software RAID has to offer here are the most important features e Threaded rebuild process e Kernel based configuration Portability of arrays between Linux machines without reconstruction e Backgrounded array reconstruction using idle system resources e Hot swappable drive support
71. are not in use and that are not a dependency of other modules in use For example the command sbin rmmod e100 unloads the e100 kernel module Another useful kernel module utility is modinfo Use the command sbin modinfo to display information about a kernel module The general syntax is sbin modinfo options lt module gt Options include d which displays a brief description of the module and p which lists the parameters the module supports For a complete list of options refer to the modinfo man page man modinfo 2 Persistent Module Loading Kernel modules are usually loaded directly by the facility that requires them which is given correct settings in the etc modprobe conf file However it is sometimes necessary to explicitly force the loading of a module at boot time Red Hat Enterprise Linux checks for the existence of the etc rc modules file at boot time which contains various commands to load modules The rc modules should be used and notrc 1local because rc modules is executed earlier in the boot process For example the following commands configure loading of the foo module at boot time as root 373 Chapter 37 Kernel Modules echo modprobe foo gt gt etc rc modules chmod x etc rc modules Tip This approach is not necessary for network and SCSI interfaces because they have their own specific mechanisms 3 Additional Resources For more information on kernel modules
72. are sent in plain text which could be intercepted and read by someone along the route between the browser and the server This chapter is not meant to be complete and exclusive documentation for any of these programs When possible this guide points to appropriate places where you can find more in depth documentation on particular subjects This chapter shows you how to install these programs You can also learn the steps necessary to generate a private key and a certificate request how to generate your own self signed certificate and how to install a certificate to use with your secure server The mod_ss1 configuration file is located at etc httpd conf d ssl conf For this file to be loaded and hence for mod_ss1 to work you must have the statement Include conf d conf in the etc httpd conf httpd conf file This statement is included by default in the default Apache HTTP Server configuration file 2 An Overview of Security Related Packages To enable the secure server you must have the following packages installed at a minimum httpd The httpd package contains the httpd daemon and related utilities configuration files icons Apache HTTP Server modules man pages and other files used by the Apache HTTP Server mod_ssl The mod_ss1 package includes the mod_ss1 module which provides strong cryptography for the Apache HTTP Server via the Secure Sockets Layer SSL and Transport Layer Security TLS protocols openssl 275
73. are the following mbr the default partition installs the boot loader on the first sector of the partition containing the kernel Or none do not install the boot loader password Sets the GRUB boot loader password to the one specified with this option This should be used to restrict access to the GRUB shell where arbitrary kernel options can be passed md5pass Similar to password except the password should already be encrypted upgrade Upgrade the existing boot loader configuration preserving the old entries This option is only available for upgrades clearpart optional Removes partitions from the system prior to creation of new partitions By default no partitions are removed Note If the clearpart command is used then the onpart command cannot be Kickstart Options used on a logical partition all Erases all partitions from the system drives Specifies which drives to clear partitions from For example the following clears all the partitions on the first two drives on the primary IDE controller clearpart drives hda hdb all initlabel Initializes the disk label to the default for your architecture for example msdos for x86 and gpt for Itanium It is useful so that the installation program does not ask if it should initialize the disk label if installing to a brand new hard drive linux Erases all Linux partitions none default Do not re
74. argument any invalid partition tables found on disks are initialized This destroys all of the contents of disks with invalid partition tables This command should be in the following format zerombr yes No other format is effective Sinclude Use the include path to file command to include the contents of another file in the kickstart file as though the contents were at the location of the include command in the kickstart file 23 Chapter 1 Kickstart Installa 4 1 Advanced Partitioning Example The following is a single integrated example showing the clearpart raid part volgroup and logvol kickstart options in action clearpart drives hda hdc initlabel Raid 1 IDE config joeuaie ieee Lil size 1000 asprimary ondrive hda partira dti size 1000 asprimary ondrive hda Ocuaemmraceinclew les size 2000 asprimary ondrive hda part raid 14 size 8000 ondrive hda part reach 15 eize i eo ondrive hda fom well Zl le 1000 asprimary ondrive hdc part aido 22 alze 1000 asprimary ondrive hdc ome BALEAS Seem 01010 Sos oscar ondrive hdc part raid 24 size 8000 ondrive hdc peat roic 2S sire i Grov ondrive hdc You can add spares x ralc fstyp Ai device md0 level RAID1 raid 11 raid 21 raid saf fstyp xt3 device mdl level RAID1 raid 12 raid 22 raid swap fstype swap device md2 level RAID1 raid
75. at http www modssl org docs 11 2 Related Books Apache The Definitive Guide 2nd edition by Ben Laurie and Peter Laurie O Reilly amp Associates Inc 287 288 Chapter 26 Authentication Configuration When a user logs in to a Red Hat Enterprise Linux system the username and password combination must be verified or authenticated as a valid and active user Sometimes the information to verify the user is located on the local system and other times the system defers the authentication to a user database on a remote system The Authentication Configuration Tool provides a graphical interface for configuring NIS LDAP and Hesiod to retrieve user information as well as for configuring LDAP Kerberos and SMB as authentication protocols Note If you configured a medium or high security level during installation or with the Security Level Configuration Tool network authentication methods including NIS and LDAP are not allowed through the firewall This chapter does not explain each of the different authentication types in detail Instead it explains how to use the Authentication Configuration Tool to configure them For more information about the specific authentication types refer to the Red Hat Enterprise Linux Reference Guide To start the graphical version of the Authentication Configuration Tool from the desktop select the Main Menu Button on the Panel gt System Settings gt Authentica
76. be allowed to connect to the PXE server for installations Operating System The operating system identifier to install on this client The list is populated from the network install instances created from the Network Installation Dialog e Serial Console This option allows use of a serial console Kickstart File The location of a kickstart file to use such as http server example com kickstart ks cfg This file can be created with the Kickstart Configurator Refer to Chapter 2 Kickstart Configurator for details Ignore the Snapshot name and Ethernet options They are only used for diskless environments For more information on configuring a diskless environment refer to Chapter 4 Diskless Environments for details 3 1 Command Line Configuration If the network server is not running X the pxeboot utility a part of the system config netboot package can be used to add hosts which are allowed to connect to the PXE server pxeboot a K lt kickstart gt O lt os identifier gt r lt value gt lt host gt The following list explains the options e a Specifies that a host is to be added 61 Chapter 3 PXE Network Instal e K lt kickstart gt The location of the kickstart file if available e O lt os identifier gt Specifies the operating system identifier as defined in Section 2 PXE Boot Configuration e r lt value gt Specifies the ram disk size e lt host gt Spe
77. be on separate lines cdrom Install from the first CD ROM drive on the system harddrive Install from a Red Hat installation tree on a local drive which must be either vfat or ext2 e partition Partition to install from such as sdb2 e dir Directory containing the RedHat directory of the installation tree For example harddrive partition hdb2 dir tmp install tree nfs Install from the NFS server specified server Server from which to install hostname or IP e dir Directory containing the RedHat directory of the installation tree For example nfs server nfsserver example com dir tmp install tree url Install from an installation tree on a remote server via FTP or HTTP For example url url http lt server gt lt dir gt or 12 Kickstart Options url url ftp lt username gt lt password gt lt server gt lt dir gt interactive optional Uses the information provided in the kickstart file during the installation but allow for inspection and modification of the values given You are presented with each screen of the installation program with the values from the kickstart file Either accept the values by clicking Next or change the values and click Next to continue Refer to the autostep command keyboard required Sets system keyboard type Here is the list of available keyboards on i386 Itanium and Alpha machines ije latimil log lor elo
78. by using iptables to configure an IP firewall If you are a new Linux user please realize that iptables may not be the best solution for you Setting up iptables can be complicated and is best tackled by experienced Linux system administrators On the other hand the benefit of using iptables is flexibility For example if you need a customized solution which provides certain hosts access to certain services iptables can provide it for you Refer to the Red Hat Enterprise Linux Reference Guide and the Red Hat Enterprise Linux Security Guide for more information about iptables Alternatively if you are looking for a utility to set general access rules for your home machine and or if you are new to Linux try the Security Level Configuration Tool system config securitylevel which allows you to select the security level for your system similar to the Firewall Configuration screen in the installation program 205 Chapter 19 Controlling Acces If you need more specific firewall rules refer to the iptables chapter in the Red Hat Enterprise Linux Reference Guide 1 Runlevels Before you can configure access to services you must understand Linux runlevels A runlevel is a state or mode that is defined by the services listed in the directory etc rc d rce lt x gt d where lt x gt is the number of the runlevel The following runlevels exist 0 Halt 1 Single user mode e 2 Not used user definable 3
79. control access to specific subnets or even specific nodes within a LAN You can also restrict certain dubious applications or programs such as trojans worms and other client server viruses from contacting their server For example some trojans scan networks for services on ports from 31337 to 31340 called the elite ports in cracking terminology Since there are no legitimate services that communicate via these non standard ports blocking 201 Chapter 18 Firewalls them can effectively diminish the chances that potentially infected nodes on your network independently communicate with their remote master servers The following rules drop all TCP traffic that attempts to use port 31337 root myServer iptables A OUTPUT o eth0O p tcp eoret Sil337 sjaoric SLSS 7 J IDO root myServer iptables A FORWARD o eth0O p tcp dport 31337 Sgro SISSY a IDIRNOP You can also block outside connections that attempt to spoof private IP address ranges to infiltrate your LAN For example if your LAN uses the 192 168 1 0 24 range you can design a rule that instructs the Internet facing network device for example eth0 to drop any packets to that device with an address in your LAN IP range Because it is recommended to reject forwarded packets as a default policy any other spoofed IP address to the external facing device ethO is rejected automatically root myServer iptables A FORWARD s 192 168 1 0
80. dev audio dev midi dev mixer dev sequencer dev sound dev beep dev snd lt cdrom gt dev cdrom dev cdroms dev cdwriter mnt cdrom You can add your own lines to this section if necessary Make sure that any lines you add refer to the appropriate device For example you could add the following line lt scanner gt dev scanner dev usb scanner Of course make sure that dev scanner is really your scanner and not say your hard drive That is the first step The second step is to define what is done with those files Look in the last section of etc security console perms for lines similar to lt console gt 0660 lt floppy gt 0660 root floppy lt console gt 0600 lt sound gt 0640 root lt console gt 0600 lt cdrom gt 0600 root disk and add a line like lt console gt 0600 lt scanner gt 0600 root Then when you log in at the console you are given ownership of the dev scanner device with the permissions of 0600 readable and writable by you only When you log out the device is owned by root and still has the permissions 0600 now readable and writable by root only 5 Enabling Console Access for Other Applications To make other applications accessible to console users a bit more work is required First of all console access only works for applications which reside in sbin or usr sbin 301 Chapter 27 Console Access so the application that you wish to run must be there
81. display the short error message shown in the Error Code column To override this default configuration select the error code and click the Edit button Choose Default to display the default short error message Choose URL to redirect the client to an external URL and enter a complete URL including the http in the Location field Choose File to redirect the client to an internal URL and enter a file location under the document root for the Web server The location must begin the a slash and be relative to the Document Root For example to redirect a 404 Not Found error code to a webpage that you created in a file called 404 html copy 404 html to DocumentRoot error 404 html In this case DocumentRoot is the Document Root directory that you have defined the default is var www html1 If the Document Root is left as the default location the file should be copied to var www error 404 html Then choose File as the Behavior for 404 Not Found error code and enter error 404 htm1 as the Location From the Default Error Page Footer menu you can choose one of the following options Show footer with email address Display the default footer at the bottom of all error pages along with the email address of the website maintainer specified by the serverAdmin http httpd apache org docs 2 0 mod core html serveradmin directive Refer to Section 3 1 1 General Options for information about configuring the ServerAdmin directive
82. each line Whitespace is not permitted in either file The at daemon atd does not have to be restarted if the access 353 Chapter 34 Automated Tasks control files are modified The access control files are read each time a user tries to execute the at Or batch commands The root user can always execute at and batch commands regardless of the access control files If the file at allow exists only users listed in it are allowed to use at or batch and the at deny file is ignored If at allow does not exist users listed in at deny are not allowed to use at Or batch 2 6 Starting and Stopping the Service To start the at service use the command sbin service atd start To stop the service use the command sbin service atd stop It is recommended that you start the service at boot time Refer to Chapter 19 Controlling Access to Services for details on starting the cron service automatically at boot time 3 Additional Resources To learn more about configuring automated tasks refer to the following resources 3 1 Installed Documentation cron man page overview of cron crontab man pages in sections 1 and 5 The man page in section 1 contains an overview of the crontab file The man page in section 5 contains the format for the file and some example entries e usr share doc at lt version gt timespec contains more detailed information about the times that can be specified for cron jobs at
83. echo part swap recommended ondisk drivel gt gt tmp part include echo part hom fstyp KES size 1 grow ondisk hdb gt gt tmp part include else 1 drive echo partitioning scheme generated in pre for 1 drive gt tmp part include echo clearpart all gt gt tmp part include echo Vpart Oot fstype ext3 size 757 gt gt tmp part imelue echo part swap recommended gt gt tmp part include echo part ESCO xe 3 size 2048 gt gt tmp part include echo part hom fstyp LES size 2048 grow gt gt tmp part include if aL This script determines the number of hard drives in the system and writes a text file with a different partitioning scheme depending on whether it has one or two drives Instead of having a set of partitioning commands in the kickstart file include the line Sinclude tmp part include The partitioning commands selected in the script are used Note The pre installation script section of kickstart cannot manage multiple install trees or source media This information must be included for each created ks cfg file as the pre installation script occurs during the second stage of the installation process 7 Post installation Script You have the option of adding commands to run on the system once the installation is complete This section must be at the end of the kickstart file and must start with the spost command This section is useful for functions suc
84. examples can be found in Section 7 1 Examples 11 1 Chroot Environment To run the post installation script outside of the chroot environment click the checkbox next to this option on the top of the Post Installation window This is equivalent to using the nochroot option in the post section To make changes to the newly installed file system within the post installation section but outside of the chroot environment you must prepend the directory name with mnt sysimage For example if you select Run outside of the chroot environment the previous example must be changed to the following echo Hackers will be punished gt mnt sysimage etc motd 11 2 Use an Interpreter To specify a scripting language to use to execute the script select the Use an interpreter option and enter the interpreter in the text box beside it For example usr bin python2 2 can be specified for a Python script This option corresponds to using post interpreter usr bin python2 2 in your kickstart file 12 Saving the File To review the contents of the kickstart file after you have finished choosing your kickstart options select File gt Preview from the pull down menu 55 Chapter 2 Kickstart Configurator You have choosen the following configuration Click Save File to save the kickstart file Generated by Kickstart Configurator platform x86 AMD64 or Intel EM64T system language lang en_US Language modules
85. have a certificate from VeriSign and you are changing your server software VeriSign is a widely used CA If you already have a VeriSign certificate for another purpose you may have been considering using your existing VeriSign certificate with your new secure server However you are not be allowed to because VeriSign issues certificates for one specific server software and IP address domain name combination If you change either of those parameters for example if you previously used a different secure server product the VeriSign certificate you obtained to use with the previous configuration will not work with the new configuration You must obtain a new certificate If you have an existing key and certificate that you can use you do not have to generate a new key and obtain a new certificate However you may need to move and rename the files which contain your key and certificate Move your existing key file to etc httpd conf ssl key server key Move your existing certificate file to etc httpd conf ssl crt server crt After you have moved your key and certificate skip to Section 9 Testing The Certificate If you are upgrading from the Red Hat Secure Web Server your old key httpsd key and certificate httpsd crt are located in etc httpd conf Move and rename your key and certificate so that the secure server can use them Use the following two commands to move and rename your key and certificate files mv etc
86. helping to complete this chapter An Updated X Window System Chapter The X Window System chapter has been revised to include information on the X11R6 8 release developed by the X Org team Before reading this guide you should be familiar with the contents of the Red Hat Enterprise Linux Installation Guide concerning installation issues the Red Hat Enterprise Linux Introduction to System Administration for basic administration concepts the Red Hat Enterprise Linux System Administration Guide for general customization instructions and the Red Hat Enterprise Linux Security Guide for security related instructions This guide contains information about topics for advanced users 2 Document Conventions Certain words in this manual are represented in different fonts styles and weights This highlighting indicates that the word is part of a specific category The categories include the following Courier font Courier font represents commands file names and paths and prompts When shown as below it indicates computer output Desktop about html logs paulwesterberg png Mail backupfiles mail reports bold Courier font Bold Courier font represents text that you are to type Such as service jonas start If you have to run a command as root the root prompt precedes the command xvi Document Conventions gconftool 2 italic Courier font Italic Courier font represents a variable such as an installation directory inst
87. hosts configures the system to resolve hostnames and IP addresses using the name servers first If the IP address cannot be resolved through the name servers the system then looks for the IP address in the etc hosts file 10 Working with Profiles 181 Chapter 17 Network Configuration Multiple logical network devices can be created for each physical hardware device For example if you have one Ethernet card in your system eth0 you can create logical network devices with different nicknames and different configuration options all to be specifically associated with etho Logical network devices are different from device aliases Logical network devices associated with the same physical device must exist in different profiles and cannot be activated simultaneously Device aliases are also associated with the same physical hardware device but device aliases associated with the same physical hardware can be activated at the same time Refer to Section 11 Device Aliases for details about creating device aliases Profiles can be used to create multiple configuration sets for different networks A configuration set can include logical devices as well as hosts and DNS settings After configuring the profiles you can use the Network Administration Tool to switch back and forth between them By default there is one profile called Common To create a new profile select Profile gt New from the pull down menu and enter a uni
88. httpd apache org docs 2 0 mod mpm_common html pidfile directive This directive sets the file in which the server records its process ID pid This file should only be readable by root In most cases it should be left to the default value The Core Dump Directory value corresponds to the CcoreDumpDi rectory http httpd apache org docs 2 0 mod mpm_common html coredumpdirectory directive The Apache HTTP Server tries to switch to this directory before executing a core dump The default value is the ServerRoot However if the user that the server runs as can not write to this directory the core dump can not be written Change this value to a directory writable by the user the server runs as if you want to write the core dumps to disk for debugging purposes The User value corresponds to the User http httpd apache org docs 2 0 mod mpm_common html user directive It sets the userid used by the server to answer requests This user s settings determine the server s access Any files inaccessible to this user are also inaccessible to your website s visitors The default for User is apache The user should only have privileges so that it can access files which are supposed to be visible to the outside world The user is also the owner of any CGI processes spawned by the server The user should not be allowed to execute any code which is not intended to be in response to HTTP requests Warning d Unless you know exactly what you are doing do n
89. httpd conf httpsd key etc httpd conf ssl key server key mv etc httpd conf httpsd crt etc httpd conf ssl crt server crt Then start your secure server with the command sbin service httpd start You are prompted to enter your passphrase After you type it in and press Enter the server starts 5 Types of Certificates If you installed your secure server from the RPM package provided by Red Hat a random key and a test certificate are generated and put into the appropriate directories Before you begin using your secure server however you must generate your own key and obtain a certificate 279 Chapter 25 Apache HTTP Secur which correctly identifies your server You need a key and a certificate to operate your secure server which means that you can either generate a self signed certificate or purchase a CA signed certificate from a CA What are the differences between the two A CA signed certificate provides two important capabilities for your server e Browsers usually automatically recognize the certificate and allow a secure connection to be made without prompting the user When a CA issues a signed certificate they are guaranteeing the identity of the organization that is providing the webpages to the browser If your secure server is being accessed by the public at large your secure server needs a certificate signed by a CA so that people who visit your website know that the website is owned by the
90. it attempts to mount your file system under the directory mnt sysimage but in read only mode If you select Skip your file system is not mounted Choose Skip if you think your file system is corrupted Once you have your system in rescue mode a prompt appears on VC virtual console 1 and VC 2 use the Cirl Alt F1 key combination to access VC 1 and Ctrl Alt F2 to access VC 2 sh 3 00b If you selected Continue to mount your partitions automatically and they were mounted successfully you are in single user mode Even if your file system is mounted the default root partition while in rescue mode is a temporary root partition not the root partition of the file system used during normal user mode runlevel 3 or 5 If you selected to mount your file system and it mounted successfully you can change the root partition of the rescue mode environment to the root partition of your file system by executing the following command chroot mnt sysimage This is useful if you need to run commands such as rpm that require your root partition to be mounted as To exit the chroot environment type exit to return to the prompt If you selected Skip you can still try to mount a partition or LVM2 logical volume manually inside rescue mode by creating a directory such as foo and typing the following command mount t ext3 dev mapper VolGroup00 LogVol02 foo In the above command foo is a directory that you have created and dev mapper VolGro
91. lt start Specifies the starting cylinder for the partition It requires that a drive be specified with ondisk Or ondrive It also requires that the ending cylinder be specified with end or the partition size be specified with size end Specifies the ending cylinder for the partition It requires that the starting cylinder be specified with start Note If partitioning fails for any reason diagnostic messages appear on virtual console Ch poweroff optional Shut down and power off the system after the installation has successfully completed Normally during a manual installation anaconda displays a message and waits for the user to press a key before rebooting During a kickstart installation if no completion method is specified the reboot option is used as default The poweroff option is roughly equivalent to the shutdown p command 18 Kickstart Options Note The powerof f option is highly dependent on the system hardware in use Specifically certain hardware components such as the BIOS APM advanced power management and ACPI advanced configuration and power interface must be able to interact with the system kernel Contact your manufacturer for more information on you system s APM ACPI abilities For other completion methods refer to the halt reboot and shutdown kickstart options raid optional Assembles a software RAID device This command is of the form raid lt mntp
92. man page description of at and batch and their command line options 354 Chapter 35 Log Files Log files are files that contain messages about the system including the kernel services and applications running on it There are different log files for different information For example there is a default system log file a log file just for security messages and a log file for cron tasks Log files can be very useful when trying to troubleshoot a problem with the system such as trying to load a kernel driver or when looking for unauthorized log in attempts to the system This chapter discusses where to find log files how to view log files and what to look for in log files Some log files are controlled by a daemon called syslogd A list of log messages maintained by syslogd can be found in the etc syslog conf configuration file 1 Locating Log Files Most log files are located in the var 1log directory Some applications such as httpd and samba have a directory within var 1log for their log files You may notice multiple files in the log file directory with numbers after them These are created when the log files are rotated Log files are rotated so their file sizes do not become too large The logrotate package contains a cron task that automatically rotates log files according to the etc logrotate conf configuration file and the configuration files in the etc logrotate d directory By default it is configured
93. may not want to allow any user at the console to run poweroff halt and reboot which are accessible from the console by default To remove these abilities run the following commands as root rm i etc security console apps poweroffrm E etc security console apps haltrm f etc security console apps reboot 3 Defining the Console The pam_console so module uses the etc security console perms file to determine the permissions for users at the system console The syntax of the file is very flexible you can edit the file so that these instructions no longer apply However the default file has a line that looks like this lt Consolessctty 0 9 0 9 we 10 91 0 917 2 0 9 0 9 310 9 When users log in they are attached to some sort of named terminal either an X server with a name like 0 Of mymachine example com 1 0 or a device like dev ttyS0 Or dev pts 2 The default is to define that local virtual consoles and local X servers are considered local but if you want to consider the serial terminal next to you on port dev ttys1 to also be local you 300 Making Files Accessible From the Console can change that line to read lt Gonsolesscty 0 9 0 9 ve 10 9 0 917 z 0 9 10 9 s 9 clew tinysl 4 Making Files Accessible From the Console In etc security console perms there is a section with lines like lt floppy gt dev fd 0 1 dev floppy mnt floppy lt sound gt dev dsp
94. more information on using token rings under Linux refer to the Linux Token Ring Project website available at http www linuxtr net To add a token ring connection follow these steps 1 Click the Devices tab 2 Click the New button on the toolbar 3 Select Token Ring connection from the Device Type list and click Forward 4 If you have already added the token ring card to the hardware list select it from the Tokenring card list Otherwise select Other Tokenring Card to add the hardware device 5 If you selected Other Tokenring Card the Select Token Ring Adapter window as shown in Figure 17 10 Token Ring Settings appears Select the manufacturer and model of the adapter Select the device name If this is the system s first token ring card select trO if this is the second token ring card select tr1 and so on The Network Administration Tool also allows the user to configure the resources for the adapter Click Forward to continue 173 Chapter 17 Network Configuration Select Token Ring Adapter Adapter IBM Olympic based PCI token ring Device tro Resource IRQ Unknown Figure 17 10 Token Ring Settings 6 On the Configure Network Settings page choose between DHCP and static IP address You may specify a hostname for the device If the device receives a dynamic IP address each time the network is started do not specify a hostname Click
95. mount when mounting the NFS exported file system on the client system There are three ways to configure an NFS file system export On demand via the command line client side automatically via the etc fstab file client side and automatically via autofs configuration files such as etc auto master and etc auto misc server side with NIS For example on demand via the command line client side mount o udp shadowman example com misc export misc local When the NFS mount is specified in etc fstab client side server usr local pub pub nfs rsize 8192 wsize 8192 timeo 14 intr udp When the NFS mount is specified in an autofs configuration file for a NIS server available for NIS enabled workstations myproject rw soft intr rsize 8192 wsize 8192 udp penguin example net proj52 Since the default is TCP if the o udp option is not specified the NFS exported file system is 223 Chapter 21 Network File Syst accessed via TCP The advantages of using TCP include the following Improved connection durability thus less NFS stale file handles messages Performance gain on heavily loaded networks because TCP acknowledges every packet unlike UDP which only acknowledges completion TCP has better congestion control than UDP which has none On a very congested network UDP packets are the first packets that are dropped This means that if NFS is writing data in 8K chunks all of that 8K must be retransmi
96. nablekrb5realmdns Enable use of DNS to find Kerberos realms disablekrb5realmdns Disable use of DNS to find Kerberos realms 293 Chapter 26 Authentication Co Option Description enablesmbauth Enable SMB disablesmbauth Disable SMB smbworkgroup lt workgroup gt Specify SMB workgroup smbservers lt server gt Specify SMB servers enablewinbind Enable winbind for user information by default disablewinbind Disable winbind for user information by default enablewinbindauth Enable winbindauth for authentication by default disablewinbindauth Disable winbindauth for authentication by default smbsecurity lt user server domain ads gt Security mode to use for Samba and winbind smbrealm lt STRING gt Default realm for Samba and winbind when security ads smbidmapuid lt lowest highest gt UID range winbind assigns to domain or ADS users smbidmapgid lt lowest highest gt GID range winbind assigns to domain or ADS users winbindseparator lt gt Character used to separate the domain and user part of winbind usernames if winbindusedefaultdomain is not enabled winbindtemplatehomedir lt home D U gt Directory that winbind users have as their home winbindtemplateprimarygroup lt nobody gt Group that winbind users have as their primary group
97. new kernel Begin testing the new kernel by rebooting the computer and watching the messages to ensure that the hardware is detected properly 369 370 Chapter 37 Kernel Modules The Linux kernel has a modular design At boot time only a minimal resident kernel is loaded into memory Thereafter whenever a user requests a feature that is not present in the resident kernel a kernel module sometimes referred to as a driver is dynamically loaded into memory During installation the hardware on the system is probed Based on this probing and the information provided by the user the installation program decides which modules need to be loaded at boot time The installation program sets up the dynamic loading mechanism to work transparently If new hardware is added after installation and the hardware requires a kernel module the system must be configured to load the proper kernel module for the new hardware When the system is booted with the new hardware the Kudzu program runs detects the new hardware if it is Supported and configures the module for it The module can also be specified manually by editing the module configuration file etc modprobe conf Note Video card modules used to display the X Window System interface are part of the xorg x11 packages not the kernel thus this chapter does not apply to them For example if a system included an SMC EtherPower 10 PCI network adapter the module configur
98. nfs Or url for FTP and HTTP as the location of the installation tree Refer to instal1 for details xconfig optional Configures the X Window System If this option is not given the user must configure X manually during the installation if X was installed this option should not be used if X is not installed on the final system noprobe Do not probe the monitor card Use specified card this card name should be from the list of cards in usr share hwdata Cards from the hwdata package The list of cards can also be found on the X Configuration screen of the Kickstart Configurator If this argument is not provided the installation program probes the PCI bus for the card Since AGP is part of the PCI bus AGP cards are detected if supported The probe order is determined by the PCI scan order of the motherboard videoram Specifies the amount of video RAM the video card has monitor Use specified monitor monitor name should be from the list of monitors in usr share hwdata MonitorsbDB from the hwdata package The list of monitors can also be found on the X Configuration screen of the Kickstart Configurator This is ignored if hsync Of vsync is provided If no monitor information is provided the installation program tries to probe for it automatically hsync Specifies the horizontal sync frequency of the monitor vsync Specifies the vertical sync frequency of the monitor default
99. only and almost nothing is set up The main advantage of emergency mode over single user mode is that the init files are not loaded If init is corrupted or not working you can still mount file systems to recover data that could be lost during a re installation To boot into emergency mode use the same method as described for single user mode in Section 3 Booting into Single User Mode with one exception replace the keyword single with the keyword emergency 71 72 Part Il File Systems File system refers to the files and directories stored on a computer A file system can have different formats called file system types These formats determine how the information is stored as files and directories Some file system types store redundant copies of the data while some file system types make hard drive access faster This part discusses the ext3 swap RAID and LVM file system types It also discusses the parted utility to manage partitions and access control lists ACLs to customize file permissions Chapier 6 The ext3 File System The default file system is the journaling ext3 file system 1 Features of ext3 The ext3 file system is essentially an enhanced version of the ext2 file system These improvements provide the following advantages Availability After an unexpected power failure or system crash also called an unclean system shutdown each mounted ext2 file system on the machine must be check
100. organization who claims to own it Before signing a certificate a CA verifies that the organization requesting the certificate was actually who they claimed to be Most Web browsers that support SSL have a list of CAs whose certificates they automatically accept If a browser encounters a certificate whose authorizing CA is not in the list the browser asks the user to either accept or decline the connection You can generate a self signed certificate for your secure server but be aware that a self signed certificate does not provide the same functionality as a CA signed certificate A self signed certificate is not automatically recognized by most Web browsers and does not provide any guarantee concerning the identity of the organization that is providing the website A CA signed certificate provides both of these important capabilities for a secure server If your secure server is to be used in a production environment a CA signed certificate is recommended The process of getting a certificate from a CA is fairly easy A quick overview is as follows 1 Create an encryption private and public key pair 2 Create a certificate request based on the public key The certificate request contains information about your server and the company hosting it 3 Send the certificate request along with documents proving your identity to a CA Red Hat does not make recommendations on which certificate authority to choose Your decision may be based on
101. own certificate called a self signed certificate or you can get a certificate from a CA A certificate from a reputable CA guarantees that a website is associated with a particular company or organization Alternatively you can create your own self signed certificate Note however that self signed certificates should not be used in most production environments Self signed certificates are not automatically accepted by a user s browser users are prompted by the browser to accept the certificate and create the secure connection Refer to Section 5 Types of Certificates for more information on the differences between self signed and CA signed certificates Once you have a self signed certificate or a signed certificate from the CA of your choice you must install it on your secure server 4 Using Pre Existing Keys and Certificates If you already have an existing key and certificate for example if you are installing the secure server to replace another company s secure server product you can probably use your existing key and certificate with the secure server The following two situations provide instances where you are not able to use your existing key and certificate e Ifyou are changing your IP address or domain name Certificates are issued for a particular IP address and domain name pair You must get a new certificate if you are changing your IP address or domain name 278 Types of Certificates If you
102. partition 16 post installation configuration 27 poweroff 18 pre installation configuration 26 raid 19 reboot 20 rootpw 20 selinux 21 shutdown 21 skipx 21 text 21 timezone 21 upgrade 22 volgroup 23 what it looks like 3 xconfig 22 zerombr 23 kickstart installations 3 CD ROM based 29 diskette based 29 file format 3 file locations 29 flash based 29 installation tree 31 LVM 14 network based 30 31 starting 31 from a boot CD ROM 32 from CD ROM 1 with a diskette 31 L LDAP 290 292 loading kernel modules 371 log files 355 see also Log Viewer description 355 examining 358 locating 355 rotating 355 syslogd 355 viewing 355 Log Viewer alerts 358 filtering 355 log file locations 356 refresh rate 356 searching 355 logical volume 79 91 logical volume group 79 Logical Volume Manager see LVM logrotate 355 lpd 338 Ismod 371 Ispci 385 LVM 79 additional resources 80 configuring LVM during installation 83 explanation of 79 installing automatic partitioning 83 85 creating a logical volume 91 creating physical volumes 88 creating the boot partition 85 creating volume groups 90 logical volume 79 91 409 Index logical volume group 79 physical extent 91 physical volume 79 88 volume groups 90 with kickstart 14 lvm LVM tools and utilities 121 LVM2 explanation of 80 Mail Transport Agent see MTA Mail Transport Agent Switcher 375 sta
103. publicly available select this check box This option is not required for viewing pages locally or for developing web pages This service requires that the httpd package be installed Enabling WWW HTTP will not open a port for HTTPS the SSL version of HTTP If this service is required select the Secure WWW HTTPS check box FTP The FTP protocol is used to transfer files between machines on a network If you plan on making your FTP server publicly available select this check box This service requires that the vsftpd package be installed SSH Secure Shell SSH is a suite of tools for logging into and executing commands on a remote machine To allow remote access to the machine via ssh select this check box This service requires that the openssh server package be installed Telnet Telnet is a protocol for logging into remote machines Telnet communications are unencrypted and provide no security from network snooping Allowing incoming Telnet access is not recommended To allow remote access to the machine via telnet select this 193 Chapter 18 Firewalls check box This service requires that the telnet server package be installed Mail SMTP SMTP is a protocol that allows remote hosts to connect directly to your machine to deliver mail You do not need to enable this service if you collect your mail from your ISP s server using POPS or IMAP or if you use a tool such as fetchmail To allow delivery of mail to your machi
104. samples are not collected for this counter event when the processor is in kernel space if 1 samples are collected even if the processor is in kernel space unit_mask Defines which unit masks are enabled for the counter user If 0 samples are not collected for the counter event when the processor is in user space if 1 samples are collected even if the processor is in user space The values of these files can be retrieved with the cat command For example cat dev oprofile 0 count 7 Example Usage While OProfile can be used by developers to analyze application performance it can also be used by system administrators to perform system analysis For example e Determine which applications and services are used the most on a system opreport can be used to determine how much processor time an application or service uses If the system is used for multiple services but is under performing the services consuming the most processor time can be moved to dedicated systems Determine processor usage The cPU_CLK_UNHALTED event can be monitored to determine the processor load over a given period of time This data can then be used to determine if additional processors or a faster processor might improve system performance 398 Graphical Interface 8 Graphical Interface Some OProfile preferences can be set with a graphical interface To start it execute the oprof_start command as root at a shell prompt A
105. software RAID creation screen 2 Choose Create a software RAID partition to create a RAID partition as shown in Figure 10 2 RAID Partition Options Note that no other RAID options such as entering a mount point are available until RAID partitions as well as RAID devices are created 100 Creating the RAID Partitions RAID Options Software RAID allows you to combine several disks into a larger RAID device A RAID device can be configured to provide additional speed and reliability compared to using an individual drive For more information on using RAID devices please consult the Red Hat Enterprise Linux AS documentation You currently have 0 software RAID partition s free to use To use RAID you must first create at least two partitions of type software RAID Then you can create a RAID device which can be formatted and mounted What do you want to do now Create a RAID device default dev md0 Clone a drive to create a RAID device default dev md0 Figure 10 2 RAID Partition Options 3 A software RAID partition must be constrained to one drive For Allowable Drives select the drive on which RAID is to be created If you have multiple drives all drives are selected and you must deselect all but one drive 101 Chapter 10 Software RAID Con Add Partition Mount Point lt Not Applicable gt File System Type software RAID sda 8676 MB IBM PSG ST39103LC A
106. supports the display of a dialog window which prompts for a password during use of the OpenSSH agent The openssh askpass gnome package can be used in conjunction with the GNOME desktop environment to display a graphical dialog window when OpenSSH programs prompt for a password If you are running GNOME and using OpenSSH utilities you should install this package The openssh server package contains the sshd secure shell daemon and related files The secure shell daemon is the server side of the OpenSSH suite and must be installed on your host to allow SSH clients to connect to your host The openssh clients package contains the client programs needed to make encrypted connections to SSH servers including the following ssh a secure replacement for rsh sftp a secure replacement for ftp for transferring files between machines and slogin a secure replacement for rlogin for remote login and telnet for communicating with another host via the Telnet protocol For more information about OpenSSH see Chapter 20 OpenSSH the Red Hat Enterprise Linux Reference Guide and the OpenSSH website at hittp www openssh com http www openssh com 276 An Overview of Certificates and Security openssl devel The openss1 devel package contains the static libraries and the include file needed to compile applications with support for various cryptographic algorithms and protocols You need to install this package only if you are deve
107. system to the file tmp network config execute the following command as root system config network cmd gt tmp network config To restore or import the network configuration from the file created from the previous command execute the following command as root system config network cmd i c f tmp network config The i option means to import the data the c option means to clear the existing configuration prior to importing and the option specifies that the file to import is as follows 187 188 Chapter 18 Firewalls Information security is commonly thought of as a process and not a product However standard security implementations usually employ some form of dedicated mechanism to control access privileges and restrict network resources to users who are authorized identifiable and traceable Red Hat Enterprise Linux includes several tools to assist administrators and security engineers with network level access control issues Firewalls are one of the core components of a network security implementation Several vendors market firewall solutions catering to all levels of the marketplace from home users protecting one PC to data center solutions safeguarding vital enterprise information Firewalls can be stand alone hardware solutions such as firewall appliances by Cisco Nokia and Sonicwall Vendors such as Checkpoint McAfee and Symantec have also developed proprietary software firewall sol
108. the DHCP configuration file includes some examples e dhcpd leases man page Explains how to configure the DHCP leases file includes some examples dhcp options man page Explains the syntax for declaring DHCP options in dhcpd conf includes some examples dhcrelay man page Explains the DHCP Relay Agent and its configuration options e usr share doc dhcp lt version gt Contains sample files README files and release notes for the specific version of the DHCP service 253 254 Chapter 24 Apache HTTP Server Configuration Red Hat Enterprise Linux provides version 2 0 of the Apache HTTP Server If you want to migrate an existing configuration file by hand refer to the migration guide at usr share doc httpd lt ver gt migration html or the Red Hat Enterprise Linux Reference Guide for details If you configured the Apache HTTP Server with the HTTP Configuration Tool in previous versions of Red Hat Enterprise Linux and then performed an upgrade you can use the HTTP Configuration Tool to migrate the configuration file to the new format for version 2 0 Start the HTTP Configuration Tool make any changes to the configuration and save it The configuration file saved will be compatible with version 2 0 The httpd and system config httpd RPM packages need to be installed to use the HTTP Configuration Tool It also requires the X Window System and root access To start the application go to the Main
109. the PPD file by clicking Browse 5 1 Confirming Printer Configuration The last step is to confirm your printer configuration Click Apply to add the print queue if the settings are correct Click Back to modify the printer configuration After applying the changes print a test page to ensure the configuration is correct Refer to Section 6 Printing a Test Page for details 6 Printing a Test Page After you have configured your printer you should print a test page to make sure the printer is functioning properly To print a test page select the printer that you want to try out from the printer list then click Print Test Page from the printer s Settings tab If you change the print driver or modify the driver options you should print a test page to test the different configuration 7 Modifying Existing Printers To delete an existing printer select the printer and click the Delete button on the toolbar The printer is removed from the printer list once you confirm deletion of the printer configuration To set the default printer select the printer from the printer list and click the Make Default Printer button in the Settings tab 7 1 The Settings Tab To change printer driver configuration click the corresponding name in the Printer list and click the Settings tab You can modify printer settings such as make and model make a printer the default print a test page change the device location URI and more Fi
110. the client to specify a hostname before receiving an IP address The DHCP server daemon in Red Hat Enterprise Linux does not support this feature PEERDNS lt answer gt where lt answer gt is one of the following e yes Modify etc resolv conf with information from the server If using DHCP then yes is the default e no Do not modify etc resolv conf SRCADDR lt address gt where lt address gt is the specified source IP address for outgoing packets e USERCTL lt answer gt where lt answer gt is one of the following e yes Non root users are allowed to control this device no Non root users are not allowed to control this device If you prefer using a graphical interface refer to Chapter 17 Network Configuration for details on using the Network Administration Tool to configure a network interface to use DHCP 252 Additional Resources Tip For advanced configurations of client DHCP options such as protocol timing lease requirements and requests dynamic DNS support aliases as well as a wide variety of values to override prepend or append to client side configurations refer to the dhclient and dhclient conf man pages 4 Additional Resources For configuration options not covered here refer to the following resources 4 1 Installed Documentation dhcpd man page Describes how the DHCP daemon works dhcpd conf man page Explains how to configure
111. the message contains the word NoKEy such as warning V3 DSA signature NOKEY key ID 0352860f Refer to Section 3 Checking a Package s Signature for more information on checking a package s signature Warning 4 If you are installing a kernel package you should use rpm ivh instead Refer to Chapter 36 Manually Upgrading the Kernel for details Installing packages is designed to be simple but you may sometimes see errors 143 Chapter 15 Package Managemen 2 2 1 Package Already Installed If the package of the same version is already installed the following is displayed Preparing HERE AE TE EERE EERE RHEE HEE HE HEE HER HEE 100 package foo 1 0 1 is already installed If the same version you are trying to install is already installed and you want to install the package anyway you can use the replacepkgs option which tells RPM to ignore the error wom Ayia replacepkgs foo 1 0 1 i386 rpm This option is helpful if files installed from the RPM were deleted or if you want the original configuration files from the RPM to be installed 2 2 2 Conflicting Files If you attempt to install a package that contains a file which has already been installed by another package or an earlier version of the same package the following is displayed Preparing HPT EE TE EERE EEE HE EE EEE E E EEE E E EE EEE EE EH HE HE EE 100 ELile Usie loilin ito from install of too 1 O 1 comrlices wi
112. the runlevel number This option is recommended if you change the Start at Boot value of multiple services and want to activate the changes immediately 3 Do nothing else You do not have to stop the httpd service You can wait until the system is rebooted for the service to stop The next time the system is booted the runlevel is initialized without the httpd service running To add a service to a runlevel select the runlevel from the Edit Runlevel pulldown menu and then select Actions gt Add Service To delete a service from a runlevel select the runlevel 209 Chapter 19 Controlling Acces from the Edit Runlevel pulldown menu select the service to be deleted from the list on the left and select Actions gt Delete Service 4 ntsysv The ntsysv utility provides a simple interface for activating or deactivating services You can use ntsysv to turn an xinetd managed service on or off You can also use ntsysv to configure runlevels By default only the current runlevel is configured To configure a different runlevel specify one or more runlevels with the 1eve1 option For example the command nt sysv level 345 configures runlevels 3 4 and 5 The ntsysv interface works like the text mode installation program Use the up and down arrows to navigate up and down the list The space bar selects unselects services and is also used to press the Ok and Cancel buttons To move between the list of services and the Ok
113. the server checks to see if the requested file is in the subdirectory exported This check is called subtree checking Select this option to disable subtree checking If the entire file system is exported selecting to disable subtree checking can increase the transfer rate This option corresponds to no_subt ree_check e Sync write operations on request Enabled by default this option does not allow the server to reply to requests before the changes made by the request are written to the disk This option corresponds to sync If this is not selected the async option is used Force sync of write operations immediately Do not delay writing to disk This option corresponds to no_wdelay The User Access tab allows the following options to be configured Treat remote root user as local root By default the user and group IDs of the root user are both 0 Root squashing maps the user ID 0 and the group ID 0 to the user and group IDs of anonymous so that root on the client does not have root privileges on the NFS server If this option is selected root is not mapped to anonymous and root on a client has root privileges to exported directories Selecting this option can greatly decrease the security of the system Do not select it unless it is absolutely necessary This option corresponds to no_root_squash Treat all client users as anonymous users If this option is selected all user and group IDs are mapped to the anonymous
114. the user s login shell or bin sh whichever is found first AS soon as the load average is below 0 8 the set of commands or script is executed If the set of commands or script tries to display information to standard out the output is emailed to the user Use the command atq to view pending jobs Refer to Section 2 3 Viewing Pending Jobs for more information Usage of the batch command can be restricted For more information refer to Section 2 5 Controlling Access to At and Batch for details 2 3 Viewing Pending Jobs To view pending at and batch jobs use the atq command The atq command displays a list of pending jobs with each job on a line Each line follows the job number date hour job class and username format Users can only view their own jobs If the root user executes the atq command all jobs for all users are displayed 2 4 Additional Command Line Options Additional command line options for at and batch include Option Description f Read the commands or shell script from a file instead of specifying them at the prompt m Send email to the user when the job has been completed v Display the time that the job is executed Table 34 1 at and batch Command Line Options 2 5 Controlling Access to At and Batch The etc at allow and etc at deny files can be used to restrict access to the at and batch commands The format of both access control files is one username on
115. to auto master misc etc auto misc timeout 60 Next add the following line to etc auto misc myproject rw soft intr rsize 8192 wsize 8192 penguin example net proj52 The first field in etc auto misc is the name of the misc subdirectory This subdirectory is created dynamically by automount It should not actually exist on the client machine The second field contains mount options such as rw for read and write access The third field is the location of the NFS export including the hostname and directory Note The directory misc must exist on the local file system There should be no subdirectories in misc on the local file system 222 Using TCP To start the autofs service at a shell prompt type the following command sbin service autofs restart To view the active mount points type the following command at a shell prompt sbin service autofs status If you modify the etc auto master configuration file while autofs is running you must tell the automount daemon s to reload by typing the following command at a shell prompt sbin service autofs reload To learn how to configure autofs to start at boot time and for information on managing services refer to Chapter 19 Controlling Access to Services 2 3 Using TCP The default transport protocol for NFSv4 is TCP however the Red Hat Enterprise Linux 5 0 0 kernel includes support for NFS over UDP To use NFS over UDP include the o udp option to
116. to install langsupport It_LT default en_US S5ystem keyboard keyboard us system mouse mouse Sytem timezone timezone Americal New_York Root password rootpw iscrypted 1 V lY6oH O0i HzgLRsSmHPexaxoffel Reboot after installation reboot lnstall OS instead of upgrade install eq gt Figure 2 17 Preview To save the kickstart file click the Save to File button in the preview window To save the file without previewing it select File gt Save File or press Ctrl S A dialog box appears Select where to save the file After saving the file refer to Section 10 Starting a Kickstart Installation for information on how to start the kickstart installation 56 Chapier 3 PXE Network Installations Red Hat Enterprise Linux allows for installation over a network using the NFS FTP or HTTP protocols A network installation can be started from a boot CD ROM a bootable flash memory drive or by using the askmethod boot option with the Red Hat Enterprise Linux CD 1 Alternatively if the system to be installed contains a network interface card NIC with Pre Execution Environment PXE support it can be configured to boot from files on another networked system rather than local media such as a CD ROM For a PXE network installation the client s NIC with PXE support sends out a broadcast request for DHCP information The DHCP server provides the client with an IP address other network informa
117. use the up and down arrow buttons beside the Hour Minute and Second in the Time section Clicking the OK button applies any changes made to the date and time the NTP daemon settings and the time zone settings It also exits the program 306 Network Time Protocol NTP Properties 2 Network Time Protocol NTP Properties As shown in Figure 28 2 NTP Properties the second tabbed window that appears is for configuring NTP Network Time Protocol Your computer can synchronize its clock with a remote time server using the Network Time Protocol NTP Servers Server clock redhat com 0 pool ntp org 1 pool ntp org 2 pool ntp org W Hide advanced options Use Local Time Source C Enable NTP Broadcast Pax Figure 28 2 NTP Properties The Network Time Protocol NTP daemon synchronizes the system clock with a remote time server or time source The application allows you to configure an NTP daemon to synchronize your system clock with a remote server To enable this feature select Enable Network Time Protocol This enables the NTP Servers list and other options You can choose one of the predefined servers edit a predefined server by clicking the Edit or add a new server name by 307 Chapter 28 Date and Time Con clicking Add Your system does not start synchronizing with the NTP server until you click OK After clicking OK the configuration is saved and the NTP daemon is started or restarte
118. use this application you must be running the X Window System have root privileges and have the system config samba RPM package installed To start the Samba Server Configuration Tool from the desktop go to the Main Menu Button on the Panel gt System Settings gt Server Settings gt Samba or type the command system config samba at a Shell prompt for example in an XTerm or a GNOME terminal 231 Chapter 22 Samba File Preferences Help 0 8B Add Properties Delete Help Figure 22 1 Samba Server Configuration Tool Note The Samba Server Configuration Tool does not display shared printers or the default stanza that allows users to view their own home directories on the Samba server 2 1 1 Configuring Server Settings The first step in configuring a Samba server is to configure the basic settings for the server and a few security options After starting the application select Preferences gt Server Settings from the pulldown menu The Basic tab is displayed as shown in Figure 22 2 Configuring Basic Server Settings Workgroup mygroup Description samba server T 232 Graphical Configuration Figure 22 2 Configuring Basic Server Settings On the Basic tab specify which workgroup the computer should be in as well as a brief description of the computer They correspond to the workgroup and server string options in smb conf Authenticatio
119. will be prompted for both From this point on you should not be prompted for a password by ssh scp OF sftp 3 4 5 Configuring ssh agent The ssh agent can be used to store your passphrase so that you do not have to enter it each time you make a ssh or scp connection If you are not running the X Window System follow these steps from a shell prompt If you are running GNOME but you do not want to configure it to prompt you for your passphrase when you log in refer to Section 3 4 4 Configuring ssh agent with GNOME this procedure will work in a terminal window such as an XTerm If you are running X but not GNOME this procedure will work in a terminal window However your passphrase will only be remembered for that terminal window it is not a global setting 1 At a shell prompt type the following command exec usr bin ssh agent S SHELL 2 Then type the command ssh add 219 Chapter 20 OpenSSH and enter your passphrase s If you have more than one key pair configured you will be prompted for each one 3 When you log out your passphrase s will be forgotten You must execute these two commands each time you log in to a virtual console or open a terminal window 4 Additional Resources The OpenSSH and OpenSSL projects are in constant development and the most up to date information for them is available from their websites The man pages for OpenSSH and OpenSSL tools are also good sources of detailed i
120. your past experiences on the experiences of your friends or colleagues or purely on monetary factors Once you have decided upon a CA you need to follow the instructions they provide on how to obtain a certificate from them 4 When the CA is satisfied that you are indeed who you claim to be they provide you with a 280 Generating a Key digital certificate 5 Install this certificate on your secure server and begin handling secure transactions Whether you are getting a certificate from a CA or generating your own self signed certificate the first step is to generate a key Refer to Section 6 Generating a Key for instructions 6 Generating a Key You must be root to generate a key First use the cd command to change to the etc httpd conf directory Remove the fake key and certificate that were generated during the installation with the following commands rm ssl key server keyrm ssl crt server crt Next create your own random key Change to the usr share ssl certs directory and type in the following command make genkey Your system displays a message similar to the following umask 77 usr bin openssl genrsa des3 1024 gt etc httpd conf ssl key server key Generating RSA private key 1024 bit long modulus one SOO E ET N E E E E A T A A T T E E E O A A E E O OSS OO PEPEE T is 65537 OxzLOMOiL Enter pass phrase You now must enter in a passphrase For security reason it sh
121. 0 0 0 0 0 01 44 kswapdod To exit top press the q key 379 Chapter 39 Gathering System Table 39 1 Interactive top commands contains useful interactive commands that you can use with top For more information refer to the top 1 manual page Command Description Space Immediately refresh the display h Display a help screen k Kill a process You are prompted for the process ID and the signal to send to it n Change the number of processes displayed You are prompted to enter the number u Sort by user Sort by memory usage P Sort by CPU usage Table 39 1 Interactive top commands If you prefer a graphical interface for top you can use the GNOME System Monitor To start it from the desktop select System gt Administration gt System Monitor or type gnome system monitor ata shell prompt such as an XTerm Select the Process Listing tab The GNOME System Monitor allows you to search for a process in the list of running processes Using the Gnome System Monitor you can also view all processes your processes or active processes The Edit menu item allows you to Stop a process Continue or start a process End a processes Kill a process Change the priority of a selected process Edit the System Monitor preferences These include changing the interval seconds to refresh the list and selecting process fields to display in the System Monit
122. 21 Network File Syst server usr local pub pub nfs rsize 8192 wsize 8192 timeo 14 intr The mount point pub must exist on the client machine before this command can be executed After adding this line to etc fstab on the client system type the command mount pub ata shell prompt and the mount point pub is mounted from the server 2 2 Mounting NFS File Systems using autofs A third option for mounting an NFS share is the use of the autofs service Autofs uses the automount daemon to manage your mount points by only mounting them dynamically when they are accessed Autofs consults the master map configuration file etc auto master to determine which mount points are defined It then starts an automount process with the appropriate parameters for each mount point Each line in the master map defines a mount point and a separate map file that defines the file systems to be mounted under this mount point For example the etc auto misc file might define mount points in the misc directory this relationship would be defined in the etc auto master file Each entry in auto master has three fields The first field is the mount point The second field is the location of the map file and the third field is optional The third field can contain information such as a timeout value For example to mount the directory proj52 on the remote machine penguin example net at the mount point misc myproject on your machine add the following line
123. 24 i eth J DROP Note There is a distinction between the prop and REJECT targets when dealing with appended rules The REJECT target denies access and returns a connection refused error to users who attempt to connect to the service The prop target as the name implies drops the packet without any warning Administrators can use their own discretion when using these targets However to avoid user confusion and attempts to continue connecting the REJECT target is recommended 7 IPTables and Connection Tracking You can inspect and restrict connections to services based on their connection state A module within iptables uses a method called connection tracking to store information about incoming connections You can allow or deny access based on the following connection states NEW A packet requesting a new connection such as an HTTP request 202 IPv6 ESTABLISHED A packet that is part of an existing connection RELATED A packet that is requesting a new connection but is part of an existing connection For example FTP uses port 21 to establish a connection but data is transferred on a different port typically port 20 INVALID A packet that is not part of any connections in the connection tracking table You can use the stateful functionality of iptables connection tracking with any network protocol even if the protocol itself is stateless such as UDP The fo
124. 265 Chapter 24 Apache HTTP Serve Order Options Process Deny list before Allow list ExecCGl Process Allow list before Deny list FollowSymLinks Includes Deny List IncludesNOEXEC v Deny access from all hosts aeria Deny hosts from SymLinkslfOwnerMatch Allow List Allow access from all hosts Allow hosts from 192 168 1 0 255 255 255 0 C Let htaccess files override directory options Directory var www html testing Figure 24 7 Directory Settings If you check the Let htaccess files override directory options the configuration directives in the htaccess file take precedence 3 Virtual Hosts Settings Virtual hosts allow you to run different servers for different IP addresses different host names or different ports on the same machine For example you can run the website for http www example com and http www anotherexample com on the same Web server using virtual hosts This option corresponds to the lt Virtual Host gt http httpd apache org docs 2 0 mod core html virtualhost directive for the default virtual host and IP based virtual hosts It corresponds to the lt NamevirtualHost gt http httpd apache org docs 2 0 mod core html namevirtualhost directive for a name based virtual host The directives set for a virtual host only apply to that particular virtual host If a directive is set server wide using the Edit Default Settings button and not defined within the virtual h
125. 3 2 Removing an LVM2 Logical Volume for Swap 0 ceeeeee 113 3 3 Removing a Swap File ccceceeeeeeeeeaeeeeeeeeeeeeeeaaaaeeeeeeeeeeeeaea 113 4 Moving Swap Space oo ececececeeeceeeeeeeeeee cece aa ea eeeeeeeeeeeeaaaaeeeeeseeeeeeaeaaaaees 114 12 Managing Disk Storage aisean mananan aeia aia iai 115 1 Standard Partitions using parted sssssesssssrrireresssrtrrrrrresrensrrrrrnesesnns 115 1 1 Viewing the Partition Table oo eee eeeeeeaeeeeeeeaaeeeeeeaaeeees 116 1 2 Creating a Partition 2 0 2 0 cececeeeee ee eeeeeeeeeeeeeeeaeaaeeeeeeeeeeeeaeaaeaees 117 1 3 Removing a Partition serors irar E S 119 1 4 Resizing a Partition secsi S 120 2 LVM Partition Management cccececeeeeeeeeeeeeeeaaeeeeeeaaeeeeeeaaeeeeeeaaenees 121 13 Implementing Disk Quotas 0 cceceeeeeeeeeee cece tees eae eeteeeeeeeeeeeaaaaeeeeeeeeeeeaaa 125 1 Configuring Disk Quotas 0 ceeeeeee ee aeeeeeeeeeeeee esse aaeeteeeeeeeeeaeaaaaneeeeeees 125 1 1 Enabling Quotas 2 00 eee eee cece cece cee eete eter tees ae aa eeteeeeeeeeeaeaaeaaes 125 1 2 Remounting the File Systems ccceceeeeeeeeeeeeeeeeeeeeeeaeaaeeees 126 1 3 Creating the Quota Database Files cccceccceeeeeeeeneeeeeeaneeees 126 1 4 Assigning Quotas per User eee eececeeeeeeeeeee sean ee eeteeeeeeeeeaeaaeaees 127 1 5 Assigning Quotas per Group ccceeeeeeeeeeee cece ee eeeeeeeeeeeeaeaaeaees 128 1 6 A
126. 4 3 2 Useful Websites 2 0 2 c ccc cece cece ence ee ennenen Ne E 374 38 Mail Transport Agent MTA Configuration 0 cccceeeeeeeeeeeeeeeaeeeeeeeeeeeeeeaee 375 VI SyStem MONIONING iraran a aaa a 377 39 Gathering System Information ccccceeceeeeeeee cece eeeeeeeeeeeeeeaaaaeeeeeeeeeeeeaea 379 1 System ProGeSSe S ssid alesis ede eke Ode ed edie 379 2 MEMOry USAGE vececcecsevertitereccchscuedees AERE EA SAADE ANA 382 3 PIGSYStOMS axceaceceds cine laesveneteehdseslansbeect apial vacteehsdvlaneseeteass tutes 383 d HardWare siriene erR saben NEREAK E REENER EAREN 384 Additonal RCSOUCOS riss marania ERTE E S 386 5 1 Installed Documentation esseessseeesesseerreenerrnnnernernnrnnneennrenennnne 386 AO FOR NOMIC eratan a n a a a dela a Ea aaa Ro 387 T Overview Of TOOIS iccssscssnssetoecsiwsenecest egecese aeaa a a a 388 2 Configuring OProf e sssini naaa a a E E 388 2 1 Specifying the Kernel c ccceceeeeeeeeeeeeeeeeeeeeeeeeeaeaaeeeeeeeeeeeeaea 388 2 2 Setting Events to Monitor ssesssssssssssesssrsrrsrrrssssrrrrrrrresesrerrnns 389 2 3 Separating Kernel and User space Profiles c ecceeesseeees 392 3 Starting and Stopping OProfile cece ceceeeeeeeeeee cece ae ee eeeeeeeeeeeeaeaaeeees 393 4 Saving Data sriain iatna esnan aaa Lol oe aa aaia 393 5 Analyzing the Dala sesensneskone eE 394 5 1 Using OPESCDOLE see imar annie aT anes EE EE E aE 394 5 2 Us
127. 8 xDSL Settings Otherwise the Select Ethernet Adapter window appears Note The installation program detects supported Ethernet devices and prompts you to configure them If you configured any Ethernet devices during the installation they are displayed in the hardware list on the Hardware tab 170 Establishing an xDSL Connection Configure DSL connection Select the ethernet device for this account Ethernet Device etho 82557 8 9 Ethernet Pro 100 Enter the provider name for this account Provider Name T Online Account Setup Enter the login name for this account Login Name Enter the password for this account Password Figure 17 8 xDSL Settings 5 If the Select Ethernet Adapter window appears select the manufacturer and model of the Ethernet card Select the device name If this is the system s first Ethernet card select ethO as the device name if this is the second Ethernet card select eth1 and so on The Network Administration Tool also allows you to configure the resources for the NIC Click Forward to continue 6 Enter the Provider Name Login Name and Password If you have a T Online account instead of entering a Login Name and Password in the default window click the T Online Account Setup button and enter the required information Click Forward to continue 7 On the Create DSL Connection page click Apply After configuring th
128. AID Devices and Mount regular file systems Figure 10 4 RAID 1 Partitions Ready Pre Device and Mount Point Creation shows successfully allocated space for the RAID 1 configuration for boot which is now ready for RAID device and mount point creation gt Disk Setu p Drive dev sda 8676 MB Model IBM PSG ST39103LC Free 8573 MB Choose where you would like Red Hat Enterprise Linux AS to Drive dev sdb 8676 MB Model IBM PSG ST39204LC R dFree be installed i MB If you do not know how to partition your system or if you raed hal witvsing ite New eat peee Rese rao im manual partitioning tools refer a Mount Point eae ee to the product documentation eis RAID Volume ype OnE MB 2A Hard Drives If you used automatic jdevisda partitioning you can either accept the current partition dev sdal software RAID 102 1 13 settings click Next or modify Free Free space 8574 14 1106 the setup using the manual V dev sdb partitioning tool dev sdb1 software RAID 102 1 B Free Free space 8574 14 1106 If you are manually partitioning your system you can see your current hard drive s and partitions displayed below Use v Hide RAID device LVM Volume Group members Hide Help Release Notes lt amp Back gt Next Figure 10 4 RAID 1 Partitions Ready Pre Device and Mount Point Creation 2 Creating the RAID D
129. Auth CJ ExportCertData IO CompatEnwVars IO StrictRequire C OptRenegotiate Fax Figure 24 9 SSL Support If an Apache HTTP Server is not configured with SSL support communications between an Apache HTTP Server and its clients are not encrypted This is appropriate for websites without personal or confidential information For example an open source website that distributes open source software and documentation has no need for secure communications However an ecommerce website that requires credit card information should use the Apache SSL support to encrypt its communications Enabling Apache SSL support enables the use of the mod_ss1 security module To enable it through the HTTP Configuration Tool you must allow access through port 443 under the Main tab gt Available Addresses Refer to Section 1 Basic Settings for details Then select the virtual host name in the Virtual Hosts tab click the Edit button choose SSL from the left hand menu and check the Enable SSL Support option as 269 Chapter 24 Apache HTTP Serve shown in Figure 24 9 SSL Support The SSL Configuration section is pre configured with the dummy digital certificate The digital certificate provides authentication for your secure Web server and identifies the secure server to client Web browsers You must purchase your own digital certificate Do not use the dummy one provided for your website For details on purchasing a CA approved
130. BEL image vmlinuz 2 6 9 1 906_EL label old iin Me ieCl alinaiewcl Z 6 Gil M06 wimg read only append root LABEL Notice that the default is not set to the new kernel To configure ELILO to boot the new kernel change the value of the default variable to the value of the 1abe1 for the image section that contains the new kernel Begin testing the new kernel by rebooting the computer and watching the messages to ensure that the hardware is detected properly 6 3 IBM S 390 and IBM eServer zSeries Systems The IBM S 390 and IBM eServer zSeries systems use z IPL as the boot loader which uses etc zipl conf as the configuration file Confirm that the file contains a section with the same version as the kernel package just installed 367 Chapter 36 Manually Upgradin defaultboot default old target boot linux image boot vmlinuz 2 6 9 5 EL ramdisk boot initrd 2 6 9 5 EL img parameters root LABEL old image boot vmlinuz 2 6 9 1 906_EL ramdisk boot initrd 2 6 9 1 906_EL img parameters root LABEL Notice that the default is not set to the new kernel To configure z IPL to boot the new kernel by default change the value of the default variable to the name of the section that contains the new kernel The first line of each section contains the name in brackets After modifying the configuration file run the following command as root to enabl
131. CA see secure server chage command forcing password expiration with 326 chkconfig 210 color depth 315 command line options printing from 346 configuration console access 299 NFS 221 console making files accessible from 301 console access configuring 299 405 Index defining 300 disabling 300 enabling 301 Cron 349 cron additional resources 354 configuration file 349 example crontabs 350 user defined tasks 351 crontab 349 CtrlAltDel shutdown disabling 299 CUPS 337 D date configuration 305 dateconfig see Time and Date Properties Tool Demilitarized Zone 201 devel package 276 df 383 DHCP 245 additional resources 253 client configuration 251 command line options 250 connecting to 251 dhcpd conf 245 dhcpd leases 250 dhcrelay 251 global parameters 246 group 248 options 246 reasons for using 245 Relay Agent 251 server configuration 245 shared network 247 starting the server 250 stopping the server 250 subnet 247 dhcpd conf 245 dhcpd leases 250 dhcrelay 251 disk quotas 125 additional resources 131 assigning per file system 129 assigning per group 128 assigning per user 127 disabling 129 enabling 125 129 etc tstab modifying 125 creating quota files 126 quotacheck running 126 grace period 128 hard limit 128 management of 129 quotacheck command using to check 130 reporting 130 soft limit 128 disk storage see disk quotas parted
132. Chapter 12 Managing Disk Storage Introduction to different methods 1 Standard Partitions using partea Many users need to view the existing partition table change the size of the partitions remove partitions or add partitions from free space or additional hard drives The utility parted allows users to perform these tasks This chapter discusses how to use parted to perform file system tasks If you want to view the system s disk space usage or monitor the disk space usage refer to Section 3 File Systems You must have the parted package installed to use the parted utility To start parted ata shell prompt as root type the command parted dev sda where dev sda is the device name for the drive you want to configure The parted prompt is displayed Type help to view a list of available commands If you want to create remove or resize a partition the device cannot be in use partitions cannot be mounted and swap space cannot be enabled The partition table should not be modified while in use because the kernel may not properly recognize the changes Data could be overwritten by writing to the wrong partition because the partition table and partitions mounted do not match The easiest way to achieve this it to boot your system in rescue mode Refer to Chapter 5 Basic System Recovery for instructions on booting into rescue mode When prompted to mount the file system select Skip Alternately if the drive does
133. D ROM CRD 8484B Hard Drives Keyboards Network devices Pointing devices Device Information RAID devices Manufacturer LG SCSI devices Driver none or built in System devices Device dev hda USB devices Video cards Figure 39 4 Hardware Browser The Device Manager application can also be used to display your system hardware This application can be started by selecting System the main menu on the panel gt Administration gt Hardware like the Hardware Browser To start the application from a terminal type hal device manager Depending on your installation preferences the graphical menu above may start this application or the Hardware Browser when clicked The figure below illustrates the Device Manager window Figure 39 5 Device Manager You can also use the 1spci command to list all PCI devices Use the command lspci v for more verbose information or lspci vv for very verbose output For example 1spci can be used to determine the manufacturer model and memory size of a system s video card 00 00 0 Host bridge ServerWorks CNB20LE Host Bridge rev 06 00 00 1 Host bridge ServerWorks CNB20LE Host Bridge rev 06 00 01 0 VGA compatible controller S3 Inc Savage 4 rev 04 00 02 0 Ethernet controller Intel Corp 82557 8 9 Ethernet Pro 100 rev 08 00 0f 0 ISA bridge ServerWorks 385 Chapter 39 Gathering System OSB4 South Bridge rev 50 00 0f 1 IDE interface ServerWorks OSB4
134. FS server exports Its format is as follows directoryhostname options The only option that needs to be specified is one of sync or async sync is recommended If sync is specified the server does not reply to requests before the changes made by the request are written to the disk For example misc export speedy example com sync would allow users from speedy example com to mount misc export with the default read only permissions but misc export speedy example com rw sync would allow users from speedy example com to mount misc export with read write privileges Refer to Section 3 2 Hostname Formats for an explanation of possible hostname formats Refer to the Red Hat Enterprise Linux Reference Guide for a list of options that can be specified y Caution T dh Be careful with spaces in the etc exports file If there are no spaces between the hostname and the options in parentheses the options apply only to the hostname If there is a space between the hostname and the options the options apply to the rest of the world For example examine the following lines misc export speedy example com rw sync 227 Chapter 21 Network File Syst misc export speedy example com rw sync The first line grants users from speedy example com read write access and denies all other users The second line grants users from speedy example com read only access the default and allows the rest of t
135. Forward to continue 7 Click Apply on the Create Tokenring Device page After configuring the token ring device it appears in the device list as shown in Figure 17 11 Token Ring Device 174 Establishing a Wireless Connection File Profile Help P B B J A New Edit Copy Delete Activate Deactivate Devices Hardase Pec OS Hosts You may configure network devices associated with d s physical hardware here Multiple logical devices can be associated with a single piece of hardware Inactive Er ir tro Token Rin A g Figure 17 11 Token Ring Device Be sure to select File gt Save to save the changes After adding the device you can edit its configuration by selecting the device from the device list and clicking Edit For example you can configure whether the device is started at boot time When the device is added it is not activated immediately as seen by its Inactive status To activate the device select it from the device list and click the Activate button If the system is configured to activate the device when the computer starts the default this step does not have to be performed again 7 Establishing a Wireless Connection Wireless Ethernet devices are becoming increasingly popular The configuration is similar to the Ethernet configuration except that it allows you to configure settings such as the SSID and key 175 Chapter 17 Network Configuration for the wirel
136. HWaddr 00 A0 CC 60 B7 G4 inet addr 192 168 100 5 Beagic sO 168 L00 255 Mesks255 255 255 0 UP BROADCAST IRUININIING MUI IEIICAS IT MTU 1500 Metric 1 RX packets 161930 errors 1 dropped 0 overruns 0 frame 0 TX packets 244570 errors 0 dropped 0 overruns 0 carrier 0 collisions 475 txqueuelen 100 RX bytes 55075551 52 5 Mb TX bytes 178108895 169 8 Mb Interrupt 10 Base address 0x9000 eth0O 1 Link encap Ethernet HWaddr OT ATCC G0 BTCA imar ackhegilO2 168 100427 Boast sl 92 163 100 255 Mask 255 255 255 0 UP BROADCAST RUNNING MULTICAST MTU 1500 Metric 1 Interrupt 10 Base address 0x9000 lo Link encap Local Loopback inet addr 127 0 0 1 Mask 255 0 0 0 UP LOOPBACK RUNNING MTU 16436 Metric 1 RX 186 Saving and Restoring the Network packets 5998 errors 0 dropped 0 overruns 0 frame 0 TX packets 5998 errors 0 dropped 0 overruns 0 carrier 0 collisions 0 txqueuelen 0 RX bytes 1627579 1 5 Mis IX bytes lozia7 15 Mis 12 Saving and Restoring the Network Configuration The command line version of Network Administration Tool can be used to save the system s network configuration to a file This file can then be used to restore the network settings to a Red Hat Enterprise Linux system This feature can be used as part of an automated backup script to save the configuration before upgrading or reinstalling or to copy the configuration to a different Red Hat Enterprise Linux system To save or export the network configuration of a
137. Linux Reference Guide for more information about LDAP Use Shadow Passwords Select this option to store passwords in shadow password format in the etc shadow file instead of etc passwd Shadow passwords are enabled by default during installation and are highly recommended to increase the security of the system The shadow utils package must be installed for this option to work For more information about shadow passwords refer to the Users and Groups chapter in the Red Hat Enterprise Linux Reference Guide Enable SMB Support This option configures PAM to use an SMB server to authenticate users Click the Configure SMB button to specify e Workgroup Specify the SMB workgroup to use e Domain Controllers Specify the SMB domain controllers to use Winbind Select this option to configure the system to connect to a Windows Active Directory or a Windows domain controller User information can be accessed as well as server authentication options can be configured Use MD5 Passwords Select this option to enable MD5 passwords which allows passwords to be up to 256 characters instead of eight characters or less It is selected by default during installation and is highly recommended for increased security 3 Command Line Version The Authentication Configuration Tool can also be run as a command line tool with no interface The command line version can be used in a configuration script or a kickstart script The authenti
138. P address means that your server makes one or more connections to the DNS in order to find out the hostname that corresponds to a particular IP address If you choose Double Reverse Lookup your server performs a double reverse DNS In other words after a reverse lookup is performed a forward lookup is performed on the result At least one of the IP addresses in the forward lookup must match the address from the first reverse lookup Generally you should leave this option set to No Reverse Lookup because the DNS requests add a load to your server and may slow it down If your server is busy the effects of trying to perform these reverse lookups or double reverse lookups may be quite noticeable Reverse lookups and double reverse lookups are also an issue for the Internet as a whole Each individual connection made to look up each hostname adds up Therefore for your own Web server s benefit as well as for the Internet s benefit you should leave this option set to No Reverse Lookup 2 3 Environment Variables Use the Environment tab to configure options for specific variables to set pass or unset for CGI scripts Sometimes it is necessary to modify environment variables for CGI scripts or server side include SSI pages The Apache HTTP Server can use the mod_env module to configure the environment variables which are passed to CGI scripts and SSI pages Use the Environment Variables page to configure the directives for this module
139. Red Hat Enterprise Linux 4 5 0 4 5 0 System Administration Guide Y redhat ISBN N A Publication date Red Hat Enterprise Linux 4 5 0 Red Hat Enterprise Linux 4 5 0 System Administration Guide Copyright 2007 Red Hat Inc Copyright 2007 by Red Hat Inc This material may be distributed only subject to the terms and conditions set forth in the Open Publication License V1 0 or later the latest version is presently available at http www opencontent org openpub Distribution of substantively modified versions of this document is prohibited without the explicit permission of the copyright holder Distribution of the work or derivative of the work in any standard paper book form for commercial purposes is prohibited unless prior permission is obtained from the copyright holder Red Hat and the Red Hat Shadow Man logo are registered trademarks of Red Hat Inc in the United States and other countries All other trademarks referenced herein are the property of their respective owners The GPG fingerprint of the security redhat com key is CA 20 86 86 2B D6 9D FC 65 F6 EC C4 21 91 80 CD DB 42 A6 0E 1801 Varsity Drive Raleigh NC 27606 2072 USA Phone 1 919 754 3700 Phone 888 733 4281 Fax 1 919 754 3701 PO Box 13588 Research Triangle Park NC 27709 USA Red Hat Enterprise Linux 4 5 0 Introduction jeepers rn a a a A al RDE XV 1 Changes To This Manual 0 c cccc
140. S 223 2 4 Preserving ACLS cccccceeeceeeeeeeeeeeeeee essa ea eeeeeeeeeeeeaaaaeeeeeeeeeeeeaea 224 3 Exporting NFS File Systems cccceeeeeeeeeeeeeeeeeeeeeeaaeaeeeeeeeeeeeeaeaaeaees 224 3 1 Command Line Configuration ccceceeeeeeeeeeeeeeeaeeeeeeeeeeeeeeeaea 227 3 2 Hostname Formats cccc scvececlatece deities cession 228 3 3 Starting and Stopping the Server ceceeeeeeeeeeneeeeeeeeeeeeeeaee 228 4 Additional RESOUICES pensisen anaa a E A SN 229 4 1 Installed Documentation 0 2 eee cence cece ee eeeeeeaneeeeeeaaeeeeeeaaeeees 229 4 2 Useful Websites o ec ee cece nee cece cee eres aaeeeeeeaaaeeeesaaaeeeeeaaeeees 229 Red Hat Enterprise Linux 4 5 0 4 3 Related BOOKS isss istrian neea EA A dobins beveceseeee cess tevodiasees 229 22 SAME N E E A E T TA E T 231 Lye Why Use Samba disirar oTa a T E tvs 231 2 Configuring a Samba Server ccccceceeeceeeeeeeeeeeeeeeeeaeaaeeeeeeeeeeeeaeaaeeees 231 2 1 Graphical Configuration cccceceeeeeeeeeeeeeeeeeeeeeeeaeaaeeeeeeeeeeeeaaa 231 2 2 Command Line Configuration ccccceeeeeeeeeeeeeeeaeeeeeeeeeeeeeeeaes 236 2 3 Encrypted Passwoids sester iS aE 237 2 4 Starting and Stopping the Server ccceceeeeeeeeeeeeeeeeeeeeeeeeeaes 239 3 Connecting to a Samba Share ce ceeececececeeeeeeeeeeeeeeeaeeeeeeeeeeeeeeeaeaaeeees 240 31 Command LINS acsee a E T debe ieeteceres 241 3 2 Mounting the Share 0
141. Samba account When guests log in to the Samba server they have the same privileges as this user This corresponds to the guest account option After clicking OK the changes are written to the configuration file and the daemon is restart thus the changes take effect immediately 2 1 2 Managing Samba Users The Samba Server Configuration Tool requires that an existing user account be active on the system acting as the Samba server before a Samba user can be added The Samba user is associated with the existing user account 234 Graphical Configuration Add User Edit User Delete User Figure 22 4 Managing Samba Users To add a Samba user select Preferences gt Samba Users from the pulldown menu and click the Add User button In the Create New Samba User window select a Unix Username from the list of existing users on the local system If the user has a different username on a Windows machine and needs to log into the Samba server from the Windows machine specify that Windows username in the Windows Username field The Authentication Mode on the Security tab of the Server Settings preferences must be set to User for this option to work Also configure a Samba Password for the Samba User and confirm it by typing it again Even if you select to use encrypted passwords for Samba it is recommended that the Samba passwords for all users are different from their system passwords To edit an existing user select the us
142. Settings 168 Establishing a Modem Connection 9 Configure the modem device baud rate flow control and modem volume If you do not know these values accept the defaults if the modem was probed successfully If you do not have touch tone dialing uncheck the corresponding checkbox Click Forward If your ISP is in the pre configured list select it Otherwise enter the required information about your ISP account If you do not know these values contact your ISP Click Forward On the IP Settings page select whether to obtain an IP address automatically or whether to set one statically Click Forward when finished On the Create Dialup Connection page click Apply After configuring the modem device it appears in the device list with the type Modem as shown in Figure 17 7 Modem Device File Profile Help Ss ff DH BSB amp New Edit Copy Delete Activate Deactivate Devices Hardase Pec ONS Hosts T You may configure network devices associated with fnt G physical hardware here Multiple logical devices can be ms associated with a single piece of hardware ce e A Inactive ppp Provider Modem Figure 17 7 Modem Device 169 Chapter 17 Network Configuration Be sure to select File gt Save to save the changes After adding the modem device you can edit its configuration by selecting the device from the device list and clicking Edit For example when the dev
143. Show footer Display just the default footer at the bottom of error pages No footer Do not display a footer at the bottom of error pages 2 2 Logging Use the Logging tab to configure options for specific transfer and error logs By default the server writes the transfer log to the var log httpd access_log file and the error log to the var log httpd error_log file The transfer log contains a list of all attempts to access the Web server It records the IP address of the client that is attempting to connect the date and time of the attempt and the file on the Web server that it is trying to retrieve Enter the name of the path and file in which to store this information If the path and file name do not start with a slash the path is relative to the server root directory as configured This option corresponds to the TransferLog http httpd apache org docs 2 0 mod mod_log_config html transferlog directive 260 Logging Environment Performance Transfer Log Log to File logs access_log Log to Program Use System Log C Use custom logging facilities Custom Log String Error Log Log to File logs error_log Log to Program Use System Log Reverse DNS Lookup Reverse Lookup Fax Figure 24 4 Logging You can configure a custom log format by checking Use custom logging facilities and entering a custom log string in the Custom Log String field This configur
144. System Monitoring This guide assumes you have a basic understanding of your Red Hat Enterprise Linux system If you need help installing Red Hat Enterprise Linux refer to the Red Hat Enterprise Linux Installation Guide For more general information about system administration refer to the Red Hat Enterprise Linux Introduction to System Administration lf you need more advanced documentation such as an overview of file systems refer to the Red Hat Enterprise Linux Reference Guide If you need security information refer to the Red Hat Enterprise Linux Security Guide 1 Changes To This Manual This manual has been reorganized for clarity and updated for the latest features of Red Hat Enterprise Linux 5 0 0 Some of the changes include XV Introduction Updated Kernel Modules and Manually Updating the Kernel Chapters The Kernel Modules and the Upgrading the Kernel Manually chapters include updated information in regards to the 2 6 kernel Special thanks to Arjan van de Ven for his hard work in helping to complete this chapter An Updated Network File System NFS Chapter The Network File System NFS chapter has been revised and reorganized to include NFSv4 Special thanks to Steve Dickson for his hard work in helping to complete this chapter An Updated OProfile Chapter The OProfile chapter has been revised and reorganized to include updated information in regards to the 2 6 kernel Special thanks to Will Cohen for his hard work in
145. Test that the logical volume has been reduced properly cat proc swaps free 112 Removing a Swap File 3 2 Removing an LVM2 Logical Volume for Swap The swap logical volume cannot be in use no system locks or processes on the volume The easiest way to achieve this it to boot your system in rescue mode Refer to Chapter 5 Basic System Recovery for instructions on booting into rescue mode When prompted to mount the file system select Skip To remove a swap volume group assuming dev VolGroup00 LogVol102 is the swap volume you want to remove 1 Disable swapping for the associated logical volume swapoff v dev VolGroup00 LogVol02 2 Remove the LVM2 logical volume of size 512 MB lvm lvremove dev VolGroup00 LogVol102 3 Remove the following entry from the etc fstab file dev VolGroup00 LogVol02 swap swap defaults 0 0 4 Test that the logical volume has been extended properly cat proc swaps free 3 3 Removing a Swap File To remove a swap file 1 Ata shell prompt as root execute the following command to disable the swap file where swapfile is the swap file swapoff v swapfile 2 Remove its entry from the etc fstab file 3 Remove the actual file rm swapfile 113 Chapter 11 Swap Space 4 Moving Swap Space To move swap space from one location to another follow the steps for removing swap space and then follow the steps for adding swap space 114
146. This will add the server to your list of known hosts ssh known_hosts as seen in the following message Warning Permanently added penguin example net RSA to the list of known IMOBIES 5 Next you will see a prompt asking for your password for the remote machine After entering your password you will be at a shell prompt for the remote machine If you do not specify a username the username that you are logged in as on the local client machine is passed to the remote machine If you want to specify a different username use the following command ssh username penguin example net You can also use the syntax ssh 1 username penguin example net 214 Using the scp Command The ssh command can be used to execute a command on the remote machine without logging in to a shell prompt The syntax is ssh hostnamecommand For example if you want to execute the command 1s usr share doc on the remote machine penguin example net type the following command at a shell prompt ssh penguin example net ls usr share doc After you enter the correct password the contents of the remote directory usr share doc will be displayed and you will return to your local shell prompt 3 2 Using the scp Command The scp command can be used to transfer files between machines over a secure encrypted connection It is similar to rcp The general syntax to transfer a local file to a remote system is as follows scp lt localfile gt u
147. Using the UPG scheme however groups are automatically assigned to files created within a directory with the setgid bit set The setgid bit makes managing group projects that share a common directory very simple because any files a user creates within the directory are owned by the group which owns the directory Let us say for example that a group of people need to work on files in the usr share emacs site lisp directory Some people are trusted to modify the directory but certainly not everyone is trusted First create an emacs group as in the following command usr sbin groupadd emacs To associate the contents of the directory with the emacs group type chown R root emacs usr share emacs site lisp Now it is possible to add the proper users to the group with the gpasswd command usr bin gpasswd a lt username gt emacs To allow users to create files within the directory use the following command chmod 775 usr share emacs site lisp When a user creates a new file it is assigned the group of the user s default private group Next set the setgid bit which assigns everything created in the directory the same group 334 Shadow Passwords permission as the directory itself emacs Use the following command chmod 2775 usr share emacs site lisp At this point because the default umask of each user is 002 all members of the emacs group can create and edit files in the usr share emacs site lisp directory wi
148. XE Installation ccceceeeeeeeeeeeeeaeeeeeeeaaeeeeeeaaeeeeeaaeeees 62 4 Diskless Environment ccceeeeeeeee cece ee eeeeeeeeee ease aa eaeeeeeeeeeseaaaaaaneeeeeeeeeaea 63 1 Configuring the NFS Server ccceceeecceeeeeeeeeeeeeeaeaaeeeeeeeeeeeaeaaanneneeeees 64 2 Finish Configuring the Diskless Environment ceeeeeeeeeeeeeeeeeeeees 64 Se ACGING OSHS arreen ene riara ENEE EEANN EREEREER ENE 65 4 Booting the Hosts 0 cccecceeeecceeee cece ee ee aaa ceeeeeeeeeeeaaaaaeeeeeeseeseaaaaneneeeees 66 5 Basic System RECOVELY ccceee cece eeeeeeeeeeee cece a e aaia 67 1 Common Problem seica cnini naai tac ed 67 1 1 Unable to Boot into Red Hat Enterprise Linux a c 67 1 2 Hardware Software Problems c ceceeeeeeeeeeeneeeeeeeeeeeeaeaaeeees 67 1 3 Root Password ooo cece eect e eee e ett ee ee eee ee ee nate eens CENENE ENER 67 2 Booting into Rescue Mode ceceeececeneeeeeeeeeeeeeeeaaeeeeeeaaeeeeeaaeeeeeaaeeees 68 2 1 Reinstalling the Boot Loader 0 0 cee eecceeeeeeenneeeeeeaeeeeeeeaaeeeeeeaaeeees 70 3 Booting into Single User Mode ccccceseeeeeeeeeeeeeeaaeeeeeeeeeeeeaeaaeaneneeeees 71 4 Booting into Emergency Mode 0 0 eeecceeeeeeeeneeeeeeaaeeeeeeaaeeeeeeaaeeeeeeaaeeees 71 Il File Systems sesetezoccsintieesustenoeche seeeeduesnsoecbannapersebwencatensauteendunenebanhaaerasbuncaeanenaadd ade 73 6 The ext3 File System m s puea aeneae i a a
149. a http bugzilla redhat com bugzilla against the component rh sag Be sure to mention the manual s identifier rh sag By mentioning this manual s identifier we know exactly which version of the guide you have If you have a suggestion for improving the documentation try to be as specific as possible when describing it If you have found an error please include the section number and some of the surrounding text so we can find it easily xviii Part l Installation Related Information The Red Hat Enterprise Linux Installation Guide discusses the installation of Red Hat Enterprise Linux and some basic post installation troubleshooting However advanced installation options are covered in this manual This part provides instructions for kickstart an automated installation technique and all related tools Use this part in conjunction with the Red Hat Enterprise Linux Installation Guide to perform any of these advanced installation tasks Chapier 1 Kickstart Installations 1 What are Kickstart Installations Many system administrators would prefer to use an automated installation method to install Red Hat Enterprise Linux on their machines To answer this need Red Hat created the kickstart installation method Using kickstart a system administrator can create a single file containing the answers to all the questions that would normally be asked during a typical installation Kickstart files can be kept on a singl
150. a warning word select the word from the list and click Delete The warning icon FN is displayed to the left of the lines that contains any of the warning words 359 Chapter 35 Log Files Warnings Show warning icon for the following key words Figure 35 5 Warning 360 Chapter 36 Manually Upgrading the Kernel The Red Hat Enterprise Linux kernel is custom built by the Red Hat kernel team to ensure its integrity and compatibility with supported hardware Before Red Hat releases a kernel it must first pass a rigorous set of quality assurance tests Red Hat Enterprise Linux kernels are packaged in RPM format so that they are easy to upgrade and verify using the Red Hat Update Agent or the up2date command The Red Hat Update Agent automatically queries the Red Hat Network servers and determines which packages need to be updated on your machine including the kernel This chapter is only useful for those individuals that require manual updating of kernel packages without using the up2date command Warning d Please note that building a custom kernel is not supported by the Red Hat Global Services Support team and therefore is not explored in this manual Tip Use of up2date is highly recommended by Red Hat for installing upgraded kernels For more information on Red Hat Network the Red Hat Update Agent and up2date refer to Chapter 16 Red Hat Network 1 Overview of Kernel Packages
151. ackages 152 tips 151 uninstalling 145 upgrading 146 using 142 verifying 148 website 153 RSA keys generating 216 RSA Version 1 keys generating 218 runlevel 1 71 runlevels 206 Samba 231 additional resources 242 configuration 231 236 default 231 smb conf 231 encrypted passwords 237 findsmb 241 graphical configuration 231 adding a share 235 configuring server settings 232 managing Samba users 234 list of active connections 239 pam_smbpass 239 reasons for using 231 share connecting to via the command line 241 connecting to with Nautilus 240 mounting 242 smbclient 241 starting the server 239 status of the server 239 stopping the server 239 syncing passwords with passwd 239 with Windows NT 4 0 2000 ME and XP 237 scp see OpenSSH secure server accessing 286 books 287 certificate authorities 280 choosing a CA 280 creation of request 282 moving it after an upgrade 279 pre existing 278 self signed 284 test vs signed vs self signed 279 testing 285 connecting to 286 explanation of security 278 installing 275 key generating 281 packages 275 413 Index port numbers 286 providing a certificate for 278 security explanation of 278 upgrading from 279 URLs 286 URLs for 286 websites 287 security 205 security level see Security Level Configuration Tool Security Level Configuration Tool enabling and disabling 192 iptables service 194 sav
152. aenteneeeees 137 72 Usetul Websites 2 222nti tivies stones entities coiven st nent deen tiecenae en 137 Ill Package Management ccccceeeeeeee ener cece ee A 139 15 Package Management with RPM 0 ccceceeeeeeeeeeeeeeeeeeeeeeeeeaaeaeeeeeseeeeeeaaa 141 1 RPM Design Goals 0 cccceceeeeeeeeeee ee ae aa eeeeeeeeeeeeaeaaeaeeeeeeeeeeaeaaeaeeeeeeees 141 vii Red Hat Enterprise Linux 4 5 0 2 USING RPM barainn a bea ta case EA AEE ea eas ae EEEE 142 2 1 Finding RPM Package cceeeeeeeeeeeeeeaeeeeeeeaaeeeeeeaaeeeeeeaaeeees 142 222 MMSCANNAG apes dic cazmsctenanendccaaghocet S 142 2 3 AU MINSTAINING vs cacesot ed aceitinc vaapese E eapvaeet T 145 24 Upgrading ics sisiese vive dave Aili EE 146 2 9 FFOSMEMING tizcssxettesceenensissxodues EE as E E ARAA 147 2 65 QUENYING iaisects ikwededtacaeiessweleaeenataeche wieeeengdicawiesaneaveelet eadetaeteeeeentin 147 2 FM ORIYING E E A T E EE E 148 3 Checking a Package s Signature cccceeeeeeeeeeeeeeeaeeeeeeeeeeeeeeeanaaeeees 149 Sele IMPOMING KOS eeren E S 150 3 2 Verifying Signature of Packages ccceceeeeeeeeeeeeeeeeeeeeeeeeaes 150 4 Impressing Your Friends with RPM sssssssssriesssrrrrssrrressrrrrssrrrresnne 151 5 Additional RESOUrCES essesi kinean nE NE K REEE KAERRA 153 5 1 Installed Documentation sssaeeseeeenreseerreeeenrrrnerrrenerrnnnnnrnnnnnnnns 153 5 2 Useful WebSites sreireerexriiuieerririveeneni e
153. al e lt os identifer gt Specify the OS identifier which is used as the directory name in the tftpboot linux install directory This corresponds to the Operating system identifier field in Figure 3 1 Network Installation Setup If FTP is selected as the installation protocol and anonymous login is not available specify a username and password for login with the following options before lt os identifer gt in the previous command A 0 u lt username gt p lt password gt For more information on command line options available for the pxeos command refer to the pxeos Man page 3 Adding PXE Hosts After configuring the network server the interface as shown in Figure 3 2 Add Hosts is displayed File Configure Help BG New Properties Delete Hostname Operating System IP Address Figure 3 2 Add Hosts The next step is to configure which hosts are allowed to connect to the PXE boot server For the command line version of this step refer to Section 3 1 Command Line Configuration To add hosts click the New button 60 Command Line Configuration Hostname or IP Address Subnet client example com C Serial Console Diskless OS Network OS Install Snapshot name Kickstart File Figure 3 3 Add a Host Enter the following information Hostname or IP Address Subnet The IP address fully qualified hostname or a subnet of systems that should
154. all_dir bin bold font Bold font represents application programs and text found on a graphical interface When shown like this OK it indicates a button on a graphical application interface Additionally the manual uses different strategies to draw your attention to pieces of information In order of how critical the information is to you these items are marked as follows Note A note is typically information that you need to understand the behavior of the system Tip A tip is typically an alternative way of performing a task Important Important information is necessary but possibly unexpected such as a configuration change that will not persist after a reboot Caution A caution indicates an act that would violate your support agreement such as recompiling the kernel xvii Introduction Warning i A warning indicates potential data loss as may happen when tuning hardware for maximum performance 3 More to Come The Red Hat Enterprise Linux System Administration Guide is part of Red Hat s growing commitment to provide useful and timely support to Red Hat Enterprise Linux users As new tools and applications are released this guide will be expanded to include them 3 1 Send in Your Feedback If you find an error in the Red Hat Enterprise Linux System Administration Guide or if you have thought of a way to make this manual better we would love to hear from you Please submit a report in Bugzill
155. allation Selects NFS FTP or HTTP as the network installation type depending on which one was configured previously If FTP is selected and anonymous FTP is not being used uncheck Anonymous FTP and provide a valid username and password combination 58 Command Line Configuration e Kickstart Specify the location of the kickstart file The file can be a URL or a file stored locally diskette The kickstart file can be created with the Kickstart Configurator Refer to Chapter 2 Kickstart Configurator for details e Server Provide the IP address or domain name of the NFS FTP or HTTP server e Location Provide the directory shared by the network server If FTP or HTTP was selected the directory must be relative to the default directory for the FTP server or the document root for the HTTP server For all network installations the directory provided must contain the RedHat directory of the installation tree After clicking OK the initrd img and vmlinuz files necessary to boot the installation program are transfered from images pxeboot in the provided installation tree to tftpboot linux install lt os identifier gt onthe tftp server the one you are running the Network Booting Tool on 2 1 Command Line Configuration If the network server is not running X the pxeos command line utility which is part of the system config netboot package can be used to configure the tftp server files Deos a l V lt cla
156. alled Documentation smb conf man page explains how to configure the Samba configuration file smbd man page describes how the Samba daemon works e smbclient and findsmb man pages learn more about these client tools e usr share doc samba lt version number gt docs help files included with the samba package 4 2 Useful Websites htto www samba org The Samba webpage contains useful documentation information about mailing lists and a list of GUI interfaces htto www samba org samba docs using_samba toc html an online version of Using 242 Useful Websites Samba 2nd Edition by Jay Ts Robert Eckstein and David Collier Brown O Reilly amp Associates 243 244 Chapter 23 Dynamic Host Configuration Protocol DHCP Dynamic Host Configuration Protocol DHCP is a network protocol for automatically assigning TCP IP information to client machines Each DHCP client connects to the centrally located DHCP server which returns that client s network configuration including the IP address gateway and DNS servers 1 Why Use DHCP DHCP is useful for automatic configuration of client network interfaces When configuring the client system the administrator can choose DHCP and instead of entering an IP address netmask gateway or DNS servers The client retrieves this information from the DHCP server DHCP is also useful if an administrator wants to change the IP addresses o
157. allow file takes precedence over the hosts deny file Permissions to grant or deny access can be based on individual IP address or hostnames or on a pattern of clients Refer to the Red Hat Enterprise Linux Reference Guide and host s_access in section 5 of the man pages man 5 hosts_access for details 2 1 xinetd To control access to Internet services use xineta which is a secure replacement for inetd The xineta daemon conserves system resources provides access control and logging and can be used to start special purpose servers xinetd can be used to provide access only to particular hosts to deny access to particular hosts to provide access to a service at certain times to limit the rate of incoming connections and or the load created by connections and more xinetd runs constantly and listens on all ports for the services it manages When a connection request arrives for one of its managed services xineta starts up the appropriate server for that service The configuration file for xineta S etc xinetd conf but the file only contains a few defaults and an instruction to include the etc xinetd d directory To enable or disable an xinetd service edit its configuration file in the etc xinetd d directory If the disable attribute is set to yes the service is disabled If the disable attribute is set to no the service is enabled You can edit any of the xinetd configuration files or change its enabled status using the Services
158. ample may be recorded on a nearby instruction opreport does not associate samples for inline functions properly opreport uses a simple address range mechanism to determine which function an address is in Inline function samples are not attributed to the inline function but rather to the function the inline function was inserted into OProfile accumulates data from multiple runs OProfile is a system wide profiler and expects processes to start up and shut down multiple times Thus samples from multiple runs accumulate Use the command opcont rol reset to clear out the samples from previous runs Non CPU limited performance problems OProfile is oriented to finding problems with CPU limited processes OProfile does not identify processes that are asleep because they are waiting on locks or for some other event to occur for example an I O device to finish an operation 387 Chapter 40 OProfile 1 Overview of Tools Table 40 1 OProfile Commands provides a brief overview of the tools provided with the oprofile package Command Description op_help Displays available events for the system s processor along with a brief description of each op_import Converts sample database files from a foreign binary format to the native format for the system Only use this option when analyzing a sample database from a different architecture opannotate Creates annotated source for an executable if the ap
159. an pages There are a number of man pages for the various applications and configuration files involved with managing users and groups Some of the more important man pages have been listed here User and Group Administrative Applications man man man man man man man man man man man chage A command to modify password aging policies and account expiration gpasswd A command to administer the etc group file groupadd A command to add groups grpck A command to verify the etc group file groupdel A command to remove groups groupmod A command to modify group membership pwck A command to verify the etc passwd and etc shadow files pwconv A tool to convert standard passwords to shadow passwords pwunconv A tool to convert shadow passwords to standard passwords useradd A command to add users userdel A command to remove users usermod A command to modify users Configuration Files man 5 group The file containing group information for the system man 5 passwd The file containing user information for the system e man 5 shadow The file containing passwords and account expiration information for the system 336 Chapter 33 Printer Configuration Printer Configuration Tool allows users to configure a printer This tool helps maintain the printer configuration file print spool directories print filters and printer classes
160. and IP Tables ccccccsecoccasssccccasbegecesssianccasdeketes senses esdugecsiseeneeeastts 190 1 1 IPTables Overview 0 cece ce eece cece cece ee eeeeeeeeeeeeaeaaeeeeeeeeeeeeaeaaeaees 190 2 Basic Firewall Configuration 0 ccccceeeeeeeeeeeeeeeeeeeeeaeeaeeeeeeeeeeeeaeaaeeaes 191 2 1 Security Level Configuration Tool c ceeeeeeeeeeeeeees 191 2 2 Enabling and Disabling the Firewall eessen 192 2 3 TRUSTE Services dsrscs iangan aan EA Aaaa 193 2 4 Other POIS sissioni tenian aeaa A E SE A EEE RAA aS 194 2 5 Saving the Settings ccceesceeeeeeeeeeeeeceeeeeeeeeeeeeeeaaaaeeeeeseeeeeeaea 194 2 6 Activating the IPTables Service errereen 194 JUs ng IP TAHOSSA eeeneed tae 195 3 1 IPTables Command Syntax 0 cccceeeeceeeeeeeeeeeeeeeaeaaeeeeeeeeeeeeaea 195 3 2 Basic Firewall Policies cccccececeeeeeeeeeeeeeeeeeeeeaeaaeeeeeeeeeeeeaea 196 3 3 Saving and Restoring IPTables Rules n 196 4 Common IPTables Filtering cccceeeeeeeeeeeeeeeeeeeeeeeaeeaeeeeeeeeeeeeaeaaeaees 197 5 FORWARD ANd NAT Rules cece cece eeeeeeee eee ee eeeeeeeeeeeeeeeeeeeeeaeeeeaaeeeeeeanees 198 viii 5 1 Postrouting and IP Masquerading cecceseeeeeeeeeeeeeeeeeeeeeeaeees 200 D2 PFOFOUUING E seedy endtecueeetiaons canteens TA 200 5 3 DMZs and IPTables eci A EEAS 201 6 Malicious Software and Spoofed IP Addresses cccccseeeeeeeeeeeeeeeeees 201 7 IPTab
161. and their utilities refer to the following resources 3 1 Installed Documentation lsmod man page description and explanation of its output insmod man page description and list of command line options modprobe man page description and list of command line options rmmod man page description and list of command line options modinfo man page description and list of command line options usr share doc kernel doc lt version gt Documentation kbuild modules txt how to compile and use kernel modules 3 2 Useful Websites http www redhat com mirrors LDP HOWT O Module HOWT O index html Linux Loadable Kernel Module HOWTO from the Linux Documentation Project 374 Chapter 38 Mail Transport Agent MTA Configuration A Mail Transport Agent MTA is essential for sending email A Mail User Agent MUA such as Evolution Mozilla Mail Thunderbird and Mutt is used to read and compose email When a user sends an email from an MUA the message is handed off to the MTA which sends the message through a series of MTAs until it reaches its destination Even if a user does not plan to send email from the system some automated tasks or system programs might use the bin mail command to send email containing log messages to the root user of the local system Red Hat Enterprise Linux 5 0 0 provides three MTAs Sendmail Postfix and Exim If all three are installed sendmail is the default MTA
162. angsupport default en_US fr_FR If you use default with only one language all languages are installed with the specified language set to the default logvol optional Create a logical volume for Logical Volume Management LVM with the syntax logvol lt mntpoint gt vgname lt name gt size lt size gt name lt name gt lt options gt The options are as follows noformat Use an existing logical volume and do not format it useexisting Use an existing logical volume and reformat it Create the partition first create the logical volume group and then create the logical volume For example part pv 01 size 3000 volgroup myvg pv 01 logvol vgname myvg size 2000 name rootvol For a detailed example of 1ogvo1 in action refer to Section 4 1 Advanced Partitioning Example mouse required Configures the mouse for the system both in GUI and text modes Options are device Device the mouse is on Such as device ttyS0 emulthree If present simultaneous clicks on the left and right mouse buttons are recognized as the middle mouse button by the X Window System This option should be used if you have a two button mouse After options the mouse type may be specified as one of the following 14 Kickstart Options alpsps 2 ascii asciips 2 atibm generic generic3 genericps 2 generic3ps 2 genericwheelps 2 genericusb generic3usb genericwheelusb geniusnm
163. annel Protocol IRQ 5 Euro ISDN EDSS1 1TR6 Figure 17 4 ISDN Settings 5 If your Internet Service Provider ISP is in the pre configured list select it Otherwise enter the required information about your ISP account If you do not know the values contact your ISP Click Forward 6 In the IP Settings window select the Encapsulation Mode and whether to obtain an IP 166 Establishing an ISDN Connection address automatically or to set a static IP instead Click Forward when finished 7 On the Create Dialup Connection page click Apply After configuring the ISDN device it appears in the device list as a device with type ISDN as shown in Figure 17 5 ISDN Device Be sure to select File gt Save to save the changes After adding the ISDN device you can edit its configuration by selecting the device from the device list and clicking Edit For example when the device is added it is configured not to start at boot time by default Edit its configuration to modify this setting Compression PPP options login name password and more can be changed When the device is added it is not activated immediately as seen by its Inactive status To activate the device select it from the device list and click the Activate button If the system is configured to activate the device when the computer starts the default this step does not have to be performed again File Profile Help s
164. annot successfully probe the monitor the installation program stops at the monitor configuration screen To continue the installation process select your monitor from the list and click Next Alternatively you can select your monitor from the list You can also specify the horizontal and vertical sync rates instead of selecting a specific monitor by checking the Specify hysnc and vsync instead of monitor option This option is useful if the monitor for the system is not listed Notice that when this option is enabled the monitor list is disabled 9 Package Selection 51 Chapter 2 Kickstart Configurator File Help Basic Configuration Installation Method Boot Loader Options Partition Information Network Configuration Authentication Firewall Configuration Display Configuration Package Selection Pre Installation Script Post Installation Script Package Selection Select packages to install Automatically Resolve Dependencies Ignore Dependencies Desktops C X Window System CI GNOME Desktop Environment CI KDE K Desktop Environment Applications C Editors C Engineering and Scientific CI Graphical Internet C Text based Internet CI Office Productivity C Sound and Video CI Graphics CI Games and Entertainment C Authoring and Publishing Servers O Server Configuration Tools AS and ES only C Web Server Figure 2 14 Package Selection The Package Selection window allows you to cho
165. anually partition with Disk Druid 2 1 Creating the oot Partition In a typical situation the disk drives are new or formatted clean The following figure Figure 8 2 Two Blank Drives Ready For Configuration shows both drives as raw devices with no partitioning configured gt Disk Setup Drive dev sda 8676 MB Model IBM PSG ST39103LC Free 8678 MB Choose where you would like Red Hat Enterprise Linux AS to Drive dev sdb 8676 MB Model IBM PSG ST39204LC LJ Free be installed 8678 MB If you do not know how to partition your system or if you 7 a need help with using the New ei manual partitioning tools refer Mount Point to the product documentation Gare RAID Volume Hard Drives Reset RAID mA Size Type Format MB Start End If you used automatic ae g V dev sda partitioning you can either accept the current partition Free Free space 8679 1 1107 settings click Next or modify V dev sdb the setup using the manual Free Free space 8679 1 1107 partitioning tool If you are manually partitioning your system you can see your current hard drive s and partitions displayed below Use Hide RAID device LVM Volume Group members Bhide Help Release Notes lt Back gt Next 85 Chapter 8 LVM Configuration Figure 8 2 Two Blank Drives Ready For Configuration Warning The boot par
166. any swap space on the device Start parted where dev sda is the device on which to remove the partition parted dev sda View the current partition table to determine the minor number of the partition to remove print Remove the partition with the command rm For example to remove the partition with minor number 3 rm 3 The changes start taking place as soon as you press Enter so review the command before committing to it After removing the partition use the print command to confirm that it is removed from the partition table You should also view the output of cat proc partitions to make sure the kernel knows the partition is removed The last step is to remove it from the etc fstab file Find the line that declares the removed partition and remove it from the file 1 4 Resizing a Partition Warning d Do not attempt to resize a partition on a device that is in use Before resizing a partition boot into rescue mode or unmount any partitions on the device and 120 LVM Partition Management turn off any swap space on the device Start parted where dev sda is the device on which to resize the partition parted dev sda View the current partition table to determine the minor number of the partition to resize as well as the start and end points for the partition print Warning d The used space of the partition to resize must not be larger than the new size To resize the partitio
167. artition is no smaller than the amount of RAM in the system and no larger than twice the amount of RAM in the system e raid lt id gt The partition is used for software RAID refer to raid pv lt id gt The partition is used for LVM refer to Logvol size The minimum partition size in megabytes Specify an integer value here such as 500 Do not append the number with MB grow Tells the partition to grow to fill available space if any or up to the maximum size setting maxsize The maximum partition size in megabytes when the partition is set to grow Specify an integer value here and do not append the number with MB 17 Chapter 1 Kickstart Installa noformat Tells the installation program not to format the partition for use with the onpart command onpart Of usepart Put the partition on the already existing device For example partition home onpart hdal puts home on dev hda1 which must already exist ondisk Or ondrive Forces the partition to be created on a particular disk For example ondisk sdb puts the partition on the second SCSI disk on the system asprimary Forces automatic allocation of the partition as a primary partition or the partitioning fails type replaced by fstype This option is no longer available Use fstype fstype Sets the file system type for the partition Valid values are ext2 ext3 swap and vfat
168. as the password he must provide to connect to a Samba share are changed To enable this feature add the following line to etc pam d system auth below the pam_cracklib so invocation password required lib security pam_smbpass so nullok use_authtok ERY lies pass 2 4 Starting and Stopping the Server On the server that is sharing directories via Samba the smb service must be running View the status of the Samba daemon with the following command sbin service smb status Start the daemon with the following command sbin service smb start Stop the daemon with the following command sbin service smb stop To start the smb service at boot time use the command sbin chkconfig level 345 smb on You can also use chkconfig ntsysv or the Services Configuration Tool to configure which services start at boot time Refer to Chapter 19 Controlling Access to Services for details Tip To view active connections to the system execute the command smbstatus 239 Chapter 22 Samba 3 Connecting to a Samba Share You can use Nautilus to view available Samba shares on your network Select Main Menu Button on the Panel gt Network Servers to view a list of Samba workgroups on your network You can also type smb in the Location bar of Nautilus to view the workgroups As shown in Figure 22 6 SMB Workgroups in Nautilus an icon appears for each available SMB workgroup on the network Eile Edit Vi
169. asy Transition It is easy to migrate from ext2 to ext3 and gain the benefits of a robust journaling file system without reformatting Refer to Section 3 Converting to an ext3 File System for more on how to perform this task The following sections walk you through the steps for creating and tuning ext3 partitions For ext2 partitions skip the partitioning and formating sections below and go directly to Section 3 Converting to an ext3 File System 75 Chapter 6 The ext3 File System 2 Creating an ext3 File System After installation it is sometimes necessary to create a new ext3 file system For example if you add a new disk drive to the system you may want to partition the drive and use the ext3 file system The steps for creating an ext3 file system are as follows 1 Create the partition using parted or fdisk 2 Format the partition with the ext3 file system using mkfs 3 Label the partition using e21abel 4 Create the mount point 5 Add the partition to the etc fstab file 3 Converting to an ext3 File System The tune2fs program can add a journal to an existing ext2 file system without altering the data already on the partition If the file system is already mounted while it is being transitioned the journal is visible as the file journal in the root directory of the file system If the file system is not mounted the journal is hidden and does not appear in the file system at all Note A def
170. ate a certificate request which you need 282 Generating a Certificate Request to Send to to send to the CA of your choice Make sure you are in the usr share ssl certs directory and type the following command make certreq Your system displays the following output and asks you for your passphrase unless you disabled the passphrase option maska usr bin openssl req new key etc httpd conf ssl key server key out etc httpd conf ssl csr server csr Using configuration from usr share ssl openssl cnf Enter pass phrase Type in the passphrase that you chose when you were generating your key unless you don t need to Next your system displays some instructions and then ask for a series of responses from you Your inputs are incorporated into the certificate request The display with example responses looks similar to the following You are about to be asked to enter information that will be incorporated into your certificate request What you are about to enter is what is called a Distinguished Name or a DN There are quite a few fields but you can leave some blank For some fields there will be a default value If you enter the field will be left blank Country Nam 2 letter code GB USState or Province Name full name Berkshire North CarolinaLocality Name eg city Newbury RaleighOrganization Name eg company My Company Ltd Test CompanyOrganizational Unit Name eg section T
171. ation file contains the following line alias eth0 tulip If a second network card is added to the system and is identical to the first card add the following line to etc modprobe conf alias ethl tulip Refer to the Red Hat Enterprise Linux Reference Guide for an alphabetical list of kernel modules and supported hardware for those modules 1 Kernel Module Utilities A group of commands for managing kernel modules is available if the module init tools package is installed Use these commands to determine if a module has been loaded successfully or when trying different modules for a piece of new hardware The command sbin 1smod displays a list of currently loaded modules For example 371 Chapter 37 Kernel Modules Module Size Used by nfs 218437 1 lockd CSOT 2 mies Delsp OaEmOC 24705 1 lp 12077 parport S7129 2 parport jae lle autofs4 DSA 2 12c_dev LIS2S O ACEC ORC 2208 iL si Ac dev sunrpc LS7O093 8 mits loelsel button 6481 0 battery 8901 O ac 4805 0 md5 4033 1 ipv6 232039 lG hein QUIS 0 e100 39493 0 mii 4673 1 e100 floppy 58481 0 sg 33377 0 dm_snapshot 17029 dm_zero 2o09 Q dm_mirror 22957 2 ext3 116809 2 jod Viz57 i Gies dm_mod 54741 6 dm_snapshot dm_zero dm_mirror ips GALS T2 CIARA S O sd_mod 1727 3 scsi_mod IZA A se dios ale leos SC moe For each line the first column is the name of the module the second column is the size of the module and the third column is th
172. ault Not Found default Method Not Allowed default Not Acceptable default Error Code 400 Bad Request Default Error Page Footer Show footer with email address Figure 24 3 Site Configuration The entries listed in the Directory Page Search List define the Di rectoryIndex http httpd apache org docs 2 0 mod mod_dir html directoryindex directive The DirectoryIndex is the default page served by the server when a user requests an index of a directory by specifying a forward slash at the end of the directory name For example when a user requests the page http www example com this_directory they are going to get either the DirectoryIndex page if it exists or a server generated directory list The server tries to find one of the files listed in the DirectoryIndex directive and returns the first one it finds If it does not find any of these files and if options Indexes is set for that directory the server generates and returns a list in HTML format of the subdirectories 259 Chapter 24 Apache HTTP Serve and files in the directory Use the Error Code section to configure Apache HTTP Server to redirect the client to a local or external URL in the event of a problem or error This option corresponds to the ErrorDocument http httpd apache org docs 2 0 mod core html errordocument directive If a problem or error occurs when a client tries to connect to the Apache HTTP Server the default action is to
173. ault installation of Red Hat Enterprise Linux uses ext3 for all file systems To convert an ext2 file system to ext3 log in as root and type sbin tune2fs j lt file_system gt where lt file_system gt is an appropriate LVM2 file system A valid LVM2 file system could be one of two types of entries e A mapped device A logical volume in a volume group for example dev mapper VolGroup00 LogVol02 A static device A traditional storage volume for example dev hdbx where habis a storage device name and x is the partition number Issue the af command to display mounted file systems For more detailed information on the 76 Reverting to an ext2 File System LVM file system refer to Chapter 8 LVM Configuration For the remainder of this section the sample commands use the following value dev mapper VolGroup00 LogVol02 After doing this be certain to change the partition type from ext2 to ext3 in the etc fstab file If you are transitioning your root file system you must use an initrd image or RAM disk to boot To create this run the mkinitrd program For information on using the mkinitrd command type man mkinitrd Also make sure your GRUB configuration loads the initrd If you fail to make this change the system still boots but the file system is mounted as ext2 instead of ext3 4 Reverting to an ext2 File System Because ext3 is relatively new some disk utilities do not yet support it F
174. ave properly selected a printer queue type you can choose either option e Select a Printer from database If you select this option choose the make of your printer from the list of Makes If your printer make is not listed choose Generic e Provide PPD file A PostScript Printer Description PPD file may also be provided with your printer This file is normally provided by the manufacturer If you are provided with a PPD file you can choose this option and use the browser bar below the option description to select the PPD file Refer to Figure 33 7 Selecting a Printer Model Printer model Select the printer manufacturer and model HP 2000C 2500C 2500CM 2563 Figure 33 7 Selecting a Printer Model After choosing an option click Forward to continue Figure 33 7 Selecting a Printer Model appears You now have to choose the corresponding model and driver for the printer 343 Chapter 33 Printer Configuration The recommended printed driver is automatically selected based on the printer model you chose The print driver processes the data that you want to print into a format the printer can understand Since a local printer is attached directly to your computer you need a printer driver to process the data that is sent to the printer If you have a PPD file for the device usually provided by the manufacturer you can select it by choosing Provide PPD file You can then browse the filesystem for
175. ay if a month is specified month any integer from 1 to 12 or the short name of the month such as jan or feb e dayofweek any integer from 0 to 7 where 0 or 7 represents Sunday or the short name of the week such as sun or mon command the command to execute the command can either be a command such as 1s proc gt gt tmp proc or the command to execute a custom script For any of the above values an asterisk can be used to specify all valid values For example an asterisk for the month value means execute the command every month within the constraints of the other values A hyphen between integers specifies a range of integers For example 1 4 means the integers 1 2 3 and 4 A list of values separated by commas specifies a list For example 3 4 6 8 indicates those four specific integers The forward slash can be used to specify step values The value of an integer can be skipped within a range by following the range with lt integer gt For example 0 59 2 can be used to define every other minute in the minute field Step values can also be used with an asterisk For instance the value 3 can be used in the month field to run the task every third month Any lines that begin with a hash mark are comments and are not processed As shown in the etc crontab file the run parts script executes the scripts in the etc cron hourly etc cron daily etc cron weekly and etc cron monthly
176. bnet then the second rule is ignored The rule to allow packets from 192 168 100 13 must precede the rule that drops 197 Chapter 18 Firewalls the remainder of the subnet To insert a rule in a specific location in an existing chain use the 1 option For example raxonelChiny7sreaienq Gp iprabiles i ANZ L aL lo Gull J ACCH2T This rule is inserted as the first rule in the INPUT chain to allow local loopback device traffic There may be times when you require remote access to the LAN Secure services for example SSH can be used for encrypted remote connection to LAN services Administrators with PPP based resources such as modem banks or bulk ISP accounts dial up access can be used to securely circumvent firewall barriers Because they are direct connections modem connections are typically behind a firewall gateway For remote users with broadband connections however special cases can be made You can configure iptables to accept connections from remote SSH clients For example the following rules allow remote SSH access root myServer iptables A INPUT p tcp dport 22 j ACCEPT root myServer iptables A OUTPUT p tcp sport 22 lt J ACCEPT These rules allow incoming and outbound access for an individual system such as a single PC directly connected to the Internet or a firewall gateway However they do not allow nodes behind the firewall gateway to access these servi
177. cation options are summarized in Table 26 1 Command Line Options 292 Command Line Version Tip These options can also be found in the authconfig man page or by typing authconfig help ata shell prompt Option Description Enable shadow passwords enableshadow disableshadow Disable shadow passwords enablemd5 Enable MD5 passwords disablemd5 Disable MD5 passwords enablenis Enable NIS disablenis Disable NIS nisdomain lt domain gt Specify NIS domain nisserver lt server gt Specify NIS server enableldap Enable LDAP for user information disableldap Disable LDAP for user information enableldaptls Enable use of TLS with LDAP disableldaptls Disable use of TLS with LDAP enableldapauth Enable LDAP for authentication disableldapauth Disable LDAP for authentication ldapserver lt server gt Specify LDAP server ldapbasedn lt dn gt Specify LDAP base DN enablekrb5 Enable Kerberos disablekrb5 Disable Kerberos krb5kdc lt kdc gt Specify Kerberos KDC krb5adminserver lt server gt Specify Kerberos administration server krb5realm lt realm gt Specify Kerberos realm enablekrb5kdcdns Enable use of DNS to find Kerberos KDCs disablekrb5kdcdns Disable use of DNS to find Kerberos KDCs
178. ccceeeeeeeeeeeeeceaeaaeeeeeeeeeeeeaeaaeeneeeeeeeeeaeaaeaees XV 2 DOCUMENT CONVENTIONS assises iinoa vevedeee sh Ea EE AEEA AEEA EE xvi 3 M re to COME cevcktieecseccvenven dened s duceaabvencc trac dianaapven dened eadcnasn enseteadevanaaneensedes xviii 3 1 Send in Your Feedback 0 ccceceeeeeeeceaeeeeeeeeeeeeeeeaaeaeeeeeeeeeeeeaeaaeeees xviii l Installation Related Information ccceeeeeteee cece nett tees test sean eeee sean eeeeeeaaeeeeeeaaeeeeeeaa 1 1 Kickstart Installations ssccecsstegosciivnecndiasacosawtveewccste S 3 1 What are Kickstart Installations ccccceceeeeeee eee eeeeeeeeeeeeeeaeaaeeeeeeeeeees 3 2 How Do You Perform a Kickstart Installation ccccceeeeeeeeeeeeeeeeeeneeeees 3 3 Creating the Kickstart File cccceeeeeeeeeaeeeeeeeeeeeeeeeaeaaeeeeeeeeeeeaeaaaaaanees 3 4 Kickstart Options 0 cccceeeee ce eeeeeeeeeee tees aaaaeeeeeeeeeeeeaeaaeadeeeeeeeeeaeaaeaaanees 4 4 1 Advanced Partitioning Example ceceecsseeeeeeaneeeeeeaaeeeeeeaaeeees 24 5 Package SClSCtlON csoma ipari set vant eeapeneees obvasidauynageaier vend ssaseeenesedvaes 24 6 Pre installation Script c cece cccccceeeeeeeeee cece ae eeeeeeeeeeaeaeaaaaaaeeeeeeseeeaaaaees 26 6 Example siniraan aaa iaa a a aaa aa EE 26 7 Post installation Script ssaiasmiiseiiinassto enia eia iaaa e a 27 Tie EXAMPIES soriire eE r ENEE EER ARE 28 8 Making the Kickstart File Available
179. cece ce eeeeeeeeeeeeeeaeaaaadeeeeeeseeaeaaaaneeeeeees 213 2 Configuring an OpenSSH Server 0 0 2 cece eeeeeeeeeeeeeeeeeeaeeeeeeeeeeeeeeeanaaeeees 213 3 Configuring an OpenSSH Client eee eeeeeeee sees aaa eeeeeeeeeeeeaeaaeaees 214 3 1 Using the ssh Command 0cececeeeeeeeeeeeeeeeeeeeeeeeaaaaeeneeeeeeeeeaas 214 3 2 Using the scp Command ceceeeeeeeeeeeeeeeeeeeeeeeeeaeaaeeeeeeeeeeeeaes 215 3 3 Using the sftp Command ceceeeee ce eeeeeeeeeeeeeeeeaeeaeeeeeeeeeeeeaes 216 3 4 Generating Key Pairs cccceceeeeeeeeeeeeeeeeeeeeeeeeeeeanaaeeeeeeeeeeeeaaa 216 4 Additional RESOUrCES ccc ceee cee eeeeee ce eeee cece eeeeceaaeeeeseaaeeeeseaneeeessanees 220 4 1 Installed Documentation cceceeeee ee eeeteeeeeeeeeeeeaeaaeeeeeeeeeeeeaea 220 4 2 Usetul WebSites ics seccecesvevaedausieveescseveteasbesehesstevecdavebeuueas taverns tes 220 4 3 Related BOOKS sicsssrcsorcssssxecceteqerctestanccsatenetes senses R 220 21 Network File System NFS 0 ceceeeeeceeeeeeeeeeeeeeeaeeaeeeeeeeeeeeeaaaaeeeeeeeeeeeeaaa 221 Te Why Use NFS 2s eset ate ea a A bane tien btaabecapetiendas ae 221 2 Mounting NFS File Systems ccceeeeeceeeeeeeeeeeeeeeeeaaaaeeeeeeeeeeeeaeaaeaaes 221 2 1 Mounting NFS File Systems using etc fstab sssssssrcrsces 221 2 2 Mounting NFS File Systems using autofs cseeeeeeeeeeee seen 222 2 0 USING TOP stssviveteattien iniaa aa iata a EEE A Na
180. ceived On a Red Hat Enterprise Linux system the oprofile RPM package must be installed to use this tool Many processors include dedicated performance monitoring hardware This hardware makes it possible to detect when certain events happen such as the requested data not being in cache The hardware normally takes the form of one or more counters that are incremented each time an event takes place When the counter value essentially rolls over an interrupt is generated making it possible to control the amount of detail and therefore overhead produced by performance monitoring OProfile uses this hardware or a timer based substitute in cases where performance monitoring hardware is not present to collect samples of performance related data each time a counter generates an interrupt These samples are periodically written out to disk later the data contained in these samples can then be used to generate reports on system level and application level performance OProfile is a useful tool but be aware of some limitations when using it Use of shared libraries Samples for code in shared libraries are not attributed to the particular application unless the separate library option is used Performance monitoring samples are inexact When a performance monitoring register triggers a sample the interrupt handling is not precise like a divide by zero exception Due to the out of order execution of instructions by the processor the s
181. ces To allow LAN access to these services you can use Network Address Translation NAT with iptables filtering rules 5 rorwarn ANd NAT Rules Most ISPs provide only a limited number of publicly routable IP addresses to the organizations they serve Administrators must therefore find alternative ways to share access to Internet services without giving public IP addresses to every node on the LAN Using private IP addresses is the most common way of allowing all nodes on a LAN to properly access internal and external network services Edge routers such as firewalls can receive incoming transmissions from the Internet and route the packets to the intended LAN node At the same time firewalls gateways can also route outgoing requests from a LAN node to the remote Internet service 198 FORWARD and NAT Rules This forwarding of network traffic can become dangerous at times especially with the availability of modern cracking tools that can spoof internal IP addresses and make the remote attacker s machine act as a node on your LAN To prevent this iptables provides routing and forwarding policies that can be implemented to prevent abnormal usage of network resources The FORWARD Chain allows an administrator to control where packets can be routed within a LAN For example to allow forwarding for the entire LAN assuming the firewall gateway is assigned an internal IP address on eth1 use the following rules root myServer
182. ch command followed by the Enter key After typing all the commands press Enter to go to a blank line and type Ctrl D Alternatively a shell script can be entered at the prompt pressing Enter after each line in the script and typing Ctrl D on a blank line to exit If a script is entered the shell used is the shell set in the user s SHELL environment the user s login shell or bin sh whichever is found first If the set of commands or script tries to display information to standard out the output is emailed to the user Use the command atq to view pending jobs Refer to Section 2 3 Viewing Pending Jobs for more information Usage of the at command can be restricted For more information refer to Section 2 5 Controlling Access to At and Batch for details 352 Viewing Pending Jobs 2 2 Configuring Batch Jobs To execute a one time task when the load average is below 0 8 use the batch command After typing the batch command the at gt prompt is displayed Type the command to execute press Enter and type Cirl D Multiple commands can be specified by typing each command followed by the Enter key After typing all the commands press Enter to go to a blank line and type Ctrl D Alternatively a shell script can be entered at the prompt pressing Enter after each line in the script and typing Ctrl D on a blank line to exit If a script is entered the shell used is the shell set in the user s SHELL environment
183. ch is included in the glibc package Hesiod is an extension of DNS that uses DNS records to store information about users groups and various other items hesiodlhs The Hesiod LHS left hand side option set in etc hesiod conf This option is used by the Hesiod library to determine the name to search DNS for when looking up information similar to LDAP s use of a base DN hesiodrhs The Hesiod RHS right hand side option set in etc hesiod conf This option is used by the Hesiod library to determine the name to search DNS for when looking up information similar to LDAP s use of a base DN Tip To look up user information for jim the Hesiod library looks up jim passwd lt LHS gt lt RHS gt which should resolve to a TXT record that looks like what his passwd entry would look like jim 501 501 Jungle Jim home 4jim bin bash For groups the situation is identical except jim group lt LHS gt lt RHS gt would be used Looking up users and groups by number is handled by making 501 uid a CNAME for jim passwd and 501 gid a CNAME for jim group Note that the LHS and RHS do not have periods put in front of them when the library determines the name for which to search so the LHS and RHS usually begin with periods enablesmbauth Enables authentication of users against an SMB server typically a Samba or Windows server SMB authentication support does not know about home directories UIDs o
184. ch rile from package para 2 0 20 To make RPM ignore this error use the replacefiles option wom Sawin replacefiles foo 1 0 1 i386 rpm 2 2 3 Unresolved Dependency RPM packages can essentially depend on other packages which means that they require other packages to be installed to run properly If you try to install a package which has an unresolved dependency output similar to the following is displayed error Failed dependencies bar so 2 is needed by foo 1 0 1 Suggested resolutions pan Arom 20 3 1336 Kou If you are installing a package from the Red Hat Enterprise Linux CD ROM set it usually 144 Uninstalling suggest the package s needed to resolve the dependency Find the suggested package s on the Red Hat Enterprise Linux CD ROMs or from the Red Hat FTP site or mirror and add it to the command wom awin tOO 10 1 Asso iwom lsaie 2 0 20 3 1386 om If installation of both packages is successful output similar to the following is displayed Preparing HHP E E PEER AE AE RE AE AE AE AE E E E E EEEE EEEE 1005 1 21200 FEAE FE E FE TE FE E FE E FE E FE FE FE E FE E FE E HE E HE E HE AE HE AE E AE HE AE E AE HE AEAEE EEEE 50 2 bar E AE AE AE a aE AE aT aE aE AEE EEE EE aE aE 100 If it does not suggest a package to resolve the dependency you can try the redhatprovides option to determine which package contains the required file You need the rpmdb redhat package installed t
185. cifies the IP address or hostname of the host to add For more information on command line options available for the pxeboot command refer to the pxeboot Man page 4 Adding a Custom Boot Message Optionally modify t ftpboot linux install msgs boot msg to use a Custom boot message 5 Performing the PXE Installation For instructions on how to configure the network interface card with PXE support to boot from the network consult the documentation for the NIC It varies slightly per card After the system boots the installation program refer to the Red Hat Enterprise Linux Installation Guide 62 Chapier 4 Diskless Environments Some networks require multiple systems with the same configuration They also require that these systems be easy to reboot upgrade and manage One solution is to use a diskless environment in which most of the operating system which can be read only is shared from a central server between the clients The individual clients have their own directories on the central server for the rest of the operating system which must be read write Each time the client boots it mounts most of the OS from the NFS server as read only and another directory as read write Each client has its own read write directory so that one client can not affect the others The following steps are necessary to configure Red Hat Enterprise Linux to run on a diskless client 1 Install Red Hat Enterprise Linux on a system s
186. commands Replace lt password gt with the password to encrypt and lt salt gt with a random combination of at least 2 of the following any alphanumeric character the slash character or a dot imoore CIV orun CHO Crot Y Soacenore gt lt sallice gt The output is the encrypted password similar to 12csGd8FRcMSM e Press Ctrl D to exit the Python interpreter e Atthe shell enter the following command replacing lt encrypted password gt with the encrypted output of the Python interpreter usermod p lt encrypted password gt lt username gt Alternatively you can assign a null password instead of an initial password To do this use the following command usermod p username A Caution CUA Using a null password while convenient is a highly unsecure practice as any third party can log in first an access the system using the unsecure username Always make sure that the user is ready to log in before unlocking an account with a null password In either case upon initial log in the user is prompted for a new password 2 5 Explaining the Process The following steps illustrate what happens if the command useradd juan is issued ona system that has shadow passwords enabled 328 Explaining the Process 1 Anew line for juan is created in etc passwa The line has the following characteristics e It begins with the username juan e There is an x for the password field indicating tha
187. d they are loaded into memory Thus the daemon does not need to be restarted if a crontab file is changed 1 2 Controlling Access to Cron The etc cron allow and etc cron deny files are used to restrict access to cron The format of both access control files is one username on each line Whitespace is not permitted in either file The cron daemon crond does not have to be restarted if the access control files are modified The access control files are read each time a user tries to add or delete a cron task The root user can always use cron regardless of the usernames listed in the access control files If the file cron allow exists only users listed in it are allowed to use cron and the cron deny file is ignored If cron allow does not exist users listed in cron deny are not allowed to use cron 1 3 Starting and Stopping the Service To start the cron service use the command sbin service crond start To stop the service use the command sbin service crond stop It is recommended that you start the service at boot time Refer to Chapter 19 Controlling Access to Services for details on starting the cron service automatically at boot time 2 At and Batch While cron is used to schedule recurring tasks the at command is used to schedule a one time task at a specific time and the batch command is used to schedule a one time task to be executed when the systems load average drops below 0 8 351 Chapter 34 Automated
188. d Time Leon TOEL AN fixed address 192 168 1 4 host raleigh option host name raleigh example com hardware ethernet 00 A1 DD 74 C3 F2 Pimec acelicess 192 i168 1 65 Example 23 3 Group Declaration To configure a DHCP server that leases a dynamic IP address to a system within a subnet modify Example 23 4 Range Parameter with your values It declares a default lease time maximum lease time and network configuration values for the clients This example assigns IP addresses in the range 192 168 1 10 and 192 168 1 100 to client systems default lease time 600 max lease time 7200 Option subnetmask 255 255 255 0p option broadcast address 192 168 1 255 Goticm wowmcers 192 168 1254 5 CHociem Comaim meme seryers 192 168 i 1 192 168 1422 option domain name example com subnet 192 166 1 0 netmask 255 255 255 0 4 cange IZ 168 L 1O LIA Los 1 100 r 248 Lease Database Example 23 4 Range Parameter To assign an IP address to a client based on the MAC address of the network interface card use the hardware ethernet parameter within a host declaration As demonstrated in Example 23 5 Static IP Address using DHCP the host apex declaration specifies that the network interface card with the MAC address 00 A0 78 8E 9E AA always receives the IP address 192 168 1 4 Note that the optional parameter host name can also be used to assign a host name to the client
189. d if it is already running Clicking the OK button applies any changes made to the date and time the NTP daemon settings and the time zone settings It also exits the program 3 Time Zone Configuration As shown in Figure 28 3 Timezone Properties the third tabbed window that appears is for configuring the system time zone To configure the system time zone click the Time Zone tab The time zone can be changed by either using the interactive map or by choosing the desired time zone from the list below the map To use the map click on the desired region The map zooms into the region selected after which you may choose the city specific to your time zone A red X appears and the time zone selection changes in the list below the map Alternatively you can also use the list below the map In the same way that the map lets you choose a region before choosing a city the list of time zones is now a treelist with cities and countries grouped within their specific continents Non geographic time zones have also been added to address needs in the scientific community Click OK to apply the changes and exit the program 308 Time Zone Configuration Network Time Protocol Time Zone Please select the nearest city in your timezone Asia Krasnoyarsk Moscow 04 Yenisei River America Montserrat America Nassau America Nipigon Eastern Time Ontario amp Quebec place America Nome Alaska Time west Alaska
190. d in the directory myproject To access the shared files the user goes into the myproject directory on his machine There are no passwords to enter or special commands to remember Users work as if the directory is on their local machines 2 Mounting NFS File Systems Use the mount command to mount a shared NFS directory from another machine mount shadowman example com misc export misc local Warning d The mount point directory on the local machine misc loca1 in the above example must exist before this command can be executed In this command shadowman example com is the hostname of the NFS file server misc export is the directory that snadowman is exporting and misc 1local is the location to mount the file system on the local machine After the mount command runs and if the client has proper permissions from the shadowman example com NFS server the client user can execute the command 1s misc local to display a listing of the files in misc export on shadowman example com 2 1 Mounting NFS File Systems using etc tstab An alternate way to mount an NFS share from another machine is to add a line to the etc fstab file The line must state the hostname of the NFS server the directory on the server being exported and the directory on the local machine where the NFS share is to be mounted You must be root to modify the etc fstab file The general syntax for the line in etc fstab is as follows 221 Chapter
191. d line 346 Printer Configuration Tool see printer configuration printtool see printer configuration processes 379 ps 379 PXE 57 PXE installations 57 adding hosts 60 boot message custom 62 configuration 57 Network Booting Tool 57 overview 57 performing 62 setting up the network server 57 pxeboot 61 pxeos 59 Q quotacheck 126 quotacheck command checking quota accuracy with 130 quotaoff 129 quotaon 129 R RAID 95 configuring software RAID during installation 99 explanation of 95 Hardware RAID 95 installing creating the boot partition 99 creating the mount points 103 creating the RAID devices 103 creating the RAID partitions 99 level 0 96 level 1 96 level 4 96 level 5 96 levels 96 reasons to use 95 412 Software RAID 95 RAM 382 rcp 215 Red Hat Network 155 Red Hat Package Manager see RPM Red Hat RPM Guide 153 rescue mode definition of 68 utilities available 70 resize2fs 77 resolution 315 RHN see Red Hat Network rmmod 373 RPM 141 additional resources 153 book about 153 checking package signatures 150 dependencies 144 design goals 141 determining file ownership with 151 documentation with 152 file conflicts resolving 144 finding deleted files with 151 freshen 147 freshening packages 147 GnuPG 150 installing 142 md5sum 149 preserving configuration files 146 querying 147 querying for file list 153 querying uninstalled p
192. d type from the Keyboard menu Choose the mouse for the system from the Mouse menu If No Mouse is selected no mouse is configured If Probe for Mouse is selected the installation program tries to automatically detect the mouse Probing works for most modern mice If the system has a two button mouse a three button mouse can be emulated by selecting Emulate 3 Buttons If this option is selected simultaneously clicking the left and right mouse buttons are recognized as a middle mouse button click From the Time Zone menu choose the time zone to use for the system To configure the system to use UTC select Use UTC clock Enter the desired root password for the system in the Root Password text entry box Type the same password in the Confirm Password text box The second field is to make sure you do not mistype the password and then realize you do not know what it is after you have completed the installation To save the password as an encrypted password in the file select Encrypt root password If the encryption option is selected when the file is saved the plain text password that you typed are encrypted and written to the kickstart file Do not type an already encrypted password and select to encrypt it Because a kickstart file is a plain text file that can be easily read it is recommended that an encrypted password be used To install languages in addition to the one selected from the Default Language pulldown menu check them in the La
193. dater 155 packages dependencies 144 determining file ownership with 151 finding deleted files from 151 freshening with RPM 147 installing 142 locating documentation for 152 obtaining list of files 153 preserving configuration files 146 querying 147 querying uninstalled 152 removing 145 tips 151 upgrading 146 verifying 148 pam_smbpass 239 pam_timestamp 302 parted 115 creating partitions 117 overview 115 411 Index removing partitions 119 resizing partitions 120 selecting device 117 table of commands 115 viewing partition table 116 partition table viewing 116 partitions creating 117 formating mkfs 118 labeling e2label 119 making mkpart 118 removing 119 resizing 120 viewing list 116 password aging 326 forcing expiration of 326 passwords shadow 335 PCI devices listing 385 physical extent 91 physical volume 79 88 pixels 315 postfix 375 PPPoE 170 Pre Execution Environment 57 printconf see printer configuration printer configuration 337 adding CUPS IPP printer 339 IPP printer 339 JetDirect printer 342 local printer 338 Samba SMB printer 340 cancel print job 346 CUPS 337 default printer 344 delete existing printer 344 IPP printer 339 JetDirect printer 342 local printer 338 managing print jobs 346 networked CUPS IPP printer 339 printing from the command line 346 Samba SMB printer 340 test page 344 viewing print spool comman
194. ddress should be the email address for the webmaster or system administrator Avoid special characters like amp and etc Some CAs reject a certificate request which contains a special character If your company name includes an ampersand amp spell it out as and instead of amp Do not use either of the extra attributes A challenge password and An optional company name To continue without entering these fields just press Enter to accept the blank default for both inputs The file etc httpd conf ssl csr server csr is created when you have finished entering your information This file is your certificate request ready to send to your CA After you have decided on a CA follow the instructions they provide on their website Their instructions tell you how to send your certificate request any other documentation that they require and your payment to them After you have fulfilled the CA s requirements they send a certificate to you usually by email Save or cut and paste the certificate that they send you as etc httpd conf ssl crt server crt Be sure to keep a backup of this file 8 Creating a Self Signed Certificate You can create your own self signed certificate Note that a self signed certificate does not provide the security guarantees of a CA signed certificate Refer to Section 5 Types of Certificates for more details about certificates To make your own self signed certificate first create a
195. desktop Specify either GNOME or KDE to set the default desktop assumes that GNOME Desktop Environment and or KDE Desktop Environment has been installed through packages startxonboot Use a graphical login on the installed system resolution 22 Advanced Partitioning Example Specify the default resolution for the X Window System on the installed system Valid values are 640x480 800x600 1024x768 1152x864 1280x1024 1400x1050 1600x1200 Be sure to specify a resolution that is compatible with the video card and monitor depth Specify the default color depth for the X Window System on the installed system Valid values are 8 16 24 and 32 Be sure to specify a color depth that is compatible with the video card and monitor volgroup optional Use to create a Logical Volume Management LVM group with the syntax volgroup lt name gt lt partition gt lt options gt The options are as follows noformat Use an existing volume group and do not format it useexisting Use an existing volume group and reformat it Create the partition first create the logical volume group and then create the logical volume For example part pv 01 eize 3000 volgroup myvg pv 01 logvol vgname myvg size 2000 name rootvol For a detailed example of volgroup in action refer to Section 4 1 Advanced Partitioning Example zerombr optional If zerombr is specified and yes is its sole
196. digital certificate refer to the Chapter 25 Apache HTTP Secure Server Configuration 3 1 3 Additional Virtual Host Options The Site Configuration Environment Variables and Directories options for the virtual hosts are the same directives that you set when you clicked the Edit Default Settings button except the options set here are for the individual virtual hosts that you are configuring Refer to Section 2 Default Settings for details on these options 4 Server Settings The Server tab allows you to configure basic server settings The default settings for these options are appropriate for most situations Main Server Performance Tuning Lock File jwarflack httpd lock PID File var runfhttpd pid Core Dump Directory etc httpd User apache Group apache Figure 24 10 Server Configuration The Lock File value corresponds to the LockFile 270 Performance Tuning http httpd apache org docs 2 0 mod mpm_common html lockfile directive This directive sets the path to the lockfile used when the server is compiled with either USE_FCNTL_SERIALIZED_ACCEPT or USE_FLOCK_SERIALIZED_ACCEPT It must be stored on the local disk It should be left to the default value unless the logs directory is located on an NFS share If this is the case the default value should be changed to a location on the local disk and to a directory that is readable only by root The PID File value corresponds to the PidFile http
197. ding all in one command line interface This section provides an overview of iptables 2 Basic Firewall Configuration Just as a firewall in a building attempts to prevent a fire from spreading a computer firewall attempts to prevent malicious software from spreading to your computer It also helps to prevent unauthorized users from accessing your computer In a default Red Hat Enterprise Linux installation a firewall exists between your computer or network and any untrusted networks for example the Internet It determines which services on your computer remote users can access A properly configured firewall can greatly increase the security of your system It is recommended that you configure a firewall for any Red Hat Enterprise Linux system with an Internet connection 2 1 Security Level Configuration Tool During the Firewall Configuration screen of the Red Hat Enterprise Linux installation you were given the option to enable a basic firewall as well as to allow specific devices incoming services and ports After installation you can change this preference by using the Security Level Configuration Tool To start this application use the following command root myServer system config selinux 191 Chapter 18 Firewalls E E Lf Please choose the security level for the system Security level Enable firewall L WWW HTTP Ll FTP Trusted services C SSH C Telnet C Mail SMTP C eth
198. directly to the network through HP JetDirect instead of a computer A Important If you add a new print queue or modify an existing one you must apply the changes for them to take effect Clicking the Apply button prompts the printer daemon to restart with the changes you have configured Clicking the Revert button discards unapplied changes 1 Adding a Local Printer To add a local printer such as one attached through a parallel port or USB port on your computer click the New Printer button in the main Printer Configuration Tool window to display the window in Figure 33 2 Adding a Printer Add a new print queue On the following screens you will be asked to provide basic information for adding a new print queue You will be able to edit the more advanced options afterwards Nothing will be done to your settings until you hit Finish on the last screen Figure 33 2 Adding a Printer Click Forward to proceed 338 Adding an IPP Printer Enter a unique name for the printer in the Printer Name field The printer name can contain letters numbers dashes and underscores _ it must not contain any spaces You can also use the Description and Location fields to further distinguish this printer from others that may be configured on your system Both of these fields are optional and may contain spaces Click Forward to open the New Printer dialogue refer to Figure 33 3 Adding a Local Printer
199. downloaded directly from Red Hat using the Package Updater standalone application or through the RHN website available at hitps rhn redhat com File Edit View Go Bookmarks Tools Help Q E Red Hat Network Your RHN x gt XY E RED HAT NETWORK LoGcGep in andriusb SIGN OUT Your RHN Systems Errata Channels Schedule Users Help Systems gt Q search No SYSTEMS SELECTED Manage Clear Your RH Your Account Your Preferences Buy Now Total systems 8 No recent actions Out of date systems 2 Ungrouped systems 8 Inactive systems 6 Errata Legend Security View All Bug Fix Updated Xpdf package fixes security issue 2 G PEE EN Q Updated less package fixes security issue z Updated krb5 packages fix security vulnerabilities 2 BUY NOW Q Updated kernel packages fix security vulnerabilities 2 Add systems Maai rovision Updated ruby package fixes denial of service issue 2 Q Updated libtiff packages fix security issues 2 Updated mozilla packages fix a buffer overflow 2 Q Updated CUPS packages fix security issues 2 Q Updated Xpdf packages fix security issues 2 Q Updated VIM packages fix security vulnerability 2 10 of 219 relevant errata shown View All Relevant Errata Figure 16 1 Your RHN Red Hat Network saves you time because you receive email when updated packages are released You do not have to search the Web for updated packages or secur
200. e 32 2 New User appears Type the username and full name for the new user in the appropriate fields Type the user s password in the Password and Confirm Password fields The password must be at least six characters Tip It is advisable to use a much longer password as this makes it more difficult for an intruder to guess it and access the account without permission It is also recommended that the password not be based on a dictionary term use a combination of letters numbers and special characters Select a login shell If you are not sure which shell to select accept the default value of bin bash The default home directory is home lt username gt You can change the home directory that is created for the user or you can choose not to create the home directory by unselecting Create home directory If you select to create the home directory default configuration files are copied from the etc skel directory into the new home directory Red Hat Enterprise Linux uses a user private group UPG scheme The UPG scheme does not add or change anything in the standard UNIX way of handling groups it offers a new convention Whenever you create a new user by default a unique group with the same name as the user is created If you do not want to create this group unselect Create a private group for the user To specify a user ID for the user select Specify user ID manually If the option is not selected the next available us
201. e DSL connection it appears in the device list as shown in Figure 17 7 Modem Device 171 Chapter 17 Network Configuration File Profile Help s f Bge Vv New Edit Copy Delete Activate Deactivate ces Hardasre Pec NS Hosts You may configure network devices associated with physical hardware here Multiple logical devices can be associated with a single piece of hardware ran ome raosne om Inactive pppd Provider xDSL Figure 17 9 xDSL Device Be sure to select File gt Save to save the changes After adding the xDSL connection you can edit its configuration by selecting the device from the device list and clicking Edit For example when the device is added it is configured not to start at boot time by default Edit its configuration to modify this setting When the device is added it is not activated immediately as seen by its Inactive status To activate the device select it from the device list and click the Activate button If the system is configured to activate the device when the computer starts the default this step does not have to be performed again 6 Establishing a Token Ring Connection A token ring network is a network in which all the computers are connected in a circular pattern 172 Establishing a Token Ring Connection A token or a special network packet travels around the token ring and allows computers to send information to each other Tip For
202. e Quota Database Files After each quota enabled file system is remounted the system is capable of working with disk quotas However the file system itself is not yet ready to support quotas The next step is to run the quotacheck command The quotacheck command examines quota enabled file systems and builds a table of the current disk usage per file system The table is then used to update the operating system s copy of disk usage In addition the file system s disk quota files are updated To create the quota files aquota user and aquota group on the file system use the c option of the quotacheck command For example if user and group quotas are enabled for the home file system create the files in the home directory quotacheck cug home The c option specifies that the quota files should be created for each file system with quotas enabled the u option specifies to check for user quotas and the g option specifies to check for group quotas If neither the u or g options are specified only the user quota file is created If only g is specified only the group quota file is created 126 Assigning Quotas per User After the files are created run the following command to generate the table of current disk usage per file system with quotas enabled quotacheck avug The options used are as follows e a Check all quota enabled locally mounted file systems e y Display verbose status information as the
203. e Unset Env http httpd apache org docs 2 0 mod mod_env html unsetenv directive 263 Chapter 24 Apache HTTP Serve To edit any of these environment values select it from the list and click the corresponding Edit button To delete any entry from the list select it and click the corresponding Delete button To learn more about environment variables in the Apache HTTP Server refer to the following http httpd apache org docs 2 0 env html 2 4 Directories Use the Directories page in the Performance tab to configure options for specific directories This corresponds to the lt Directory gt http httpd apache org docs 2 0 mod core html directory directive Page Options Performance Default Directory Options ExecCGl FollowSymLinks Includes IncludesNOEXEC Indexes SymLinkslfOwnerMatch Directory 264 Directories Figure 24 6 Directories Click the Edit button in the top right hand corner to configure the Default Directory Options for all directories that are not specified in the Directory list below it The options that you choose are listed as the opt ions http httpd apache org docs 2 0 mod core html options directive within the lt Directory gt http nttpd apache org docs 2 0 mod core html directory directive You can configure the following options ExecCGl Allow execution of CGI scripts CGI scripts are not executed if this option is not chosen FollowSymLinks Allow
204. e ad hoc DNS update mode and the interim DHCP DNS interaction draft update mode If and when these two are accepted as part of the Internet Engineering Task Force IETF standards process there will be a third mode the standard DNS update method The DHCP server must be configured to use one of the two current schemes Version 3 0b2pl11 and previous versions used the ad hoc mode however it 245 Chapter 23 Dynamic Host Conf has been deprecated To keep the same behavior add the following line to the top of the configuration file ddns update style ad hoc To use the recommended mode add the following line to the top of the configuration file ddns update style interim Refer to the dhcpd conf man page for details about the different modes There are two types of statements in the configuration file e Parameters State how to perform a task whether to perform a task or what network configuration options to send to the client e Declarations Describe the topology of the network describe the clients provide addresses for the clients or apply a group of parameters to a group of declarations Some parameters must start with the opt ion keyword and are referred to as options Options configure DHCP options whereas parameters configure values that are not optional or control how the DHCP server behaves Parameters including options declared before a section enclosed in curly brackets are conside
205. e at hitp www redhat com apps supporv errata A Red Hat FTP Mirror Site available at http www redhat com download mirror html Red Hat Network Refer to Chapter 16 Red Hat Network for more details on Red Hat Network 2 2 Installing 142 Installing RPM packages typically have file names like foo 1 0 1 1386 rpm The file name includes the package name foo version 1 0 release 1 and architecture i386 To install a package log in as root and type the following command at a shell prompt wom Uwi oo MOn 1 1386 mom If installation is successful the following output is displayed Preparing HHP E AE E E PERE AE AE AE AE AE AE AE AE E E E E EEEE EEEE 100 1 go HERP E AE E E PEPER EERE PERERERRRERERERERER REESE 100 As you can see RPM prints out the name of the package and then prints a succession of hash marks as the package is installed as a progress meter The signature of a package is checked automatically when installing or upgrading a package The signature confirms that the package was signed by an authorized party For example if the verification of the signature fails an error message such as the following is displayed error V3 DSA signature BAD key ID 0352860f If it is a new header only signature an error message such as the following is displayed error Header V3 DSA signature BAD key ID 0352860f If you do not have the appropriate key installed to verify the signature
206. e autofs command line configuration 227 configuration 221 diskless environment configuring for 64 exporting 224 hostname formats 228 mounting 221 over TCP 223 starting the server 228 status of the server 228 410 stopping the server 228 NFS Server Configuration Tool 224 NIS 290 NTP configuring 307 ntpd 307 ntpd 307 ntsysv 210 O O Reilly amp Associates Inc 274 O Reilly amp Associates Inc 229 opannotate see OProfile opcontrol see OProfile OpenLDAP 290 292 openidap clients 290 OpenSSH 213 additional resources 220 client 214 scp 215 sftp 216 ssh 214 DSA keys generating 217 generating key pairs 216 RSA keys generating 216 RSA Version 1 keys generating 218 server 213 etc ssh sshd_config 213 starting and stopping 213 ssh add 219 ssh agent 219 with GNOME 218 ssh keygen DSA 217 RSA 216 RSA Version 1 218 OpenSSL additional resources 220 opreport see OProfile OProfile 387 dev oprofile 398 additional resources 403 configuring 388 separating profiles 392 events sampling rate 391 setting 389 monitoring the kernel 388 opannotate 397 opcontrol 388 no vmlinux 389 start 393 vmlinux 388 opreport 394 on asingle executable 395 oprofiled 393 log file 393 op_help 391 overview of tools 388 reading data 394 saving data 393 starting 393 unit mask 392 oprofiled see OProfile oprof_start 399 op_help 391 P Package Up
207. e configuration file The default location is etc dhcpd conf e 1f lt filename gt Specify the location of the lease database file If a lease database file already exists it is very important that the same file be used every time the DHCP server is started It is strongly recommended that this option only be used for debugging purposes on non production machines The default location is var lib dhcp dhcpd leases q Do not print the entire copyright message when starting the daemon 2 4 DHCP Relay Agent The DHCP Relay Agent dhcrelay allows for the relay of DHCP and BOOTP requests from a subnet with no DHCP server on it to one or more DHCP servers on other subnets When a DHCP client requests information the DHCP Relay Agent forwards the request to the list of DHCP servers specified when the DHCP Relay Agent is started When a DHCP server returns a reply the reply is broadcast or unicast on the network that sent the original request The DHCP Relay Agent listens for DHCP requests on all interfaces unless the interfaces are specified in etc sysconfig dhcrelay with the INTERFACES directive To start the DHCP Relay Agent use the command service dhcrelay start 3 Configuring a DHCP Client The first step for configuring a DHCP client is to make sure the kernel recognizes the network interface card Most cards are recognized during the installation process and the system is configured to use the correct kernel m
208. e cron RPM package must be installed and the crond service must be running To determine if the package is installed use the rpm q vixie cron command To determine if the service is running use the command sbin service crond status 1 1 Configuring Cron Tasks The main configuration file for cron etc crontab contains the following lines SHELL bin bash PATH sbin bin usr sbin usr bin MATLTO root HOME run parts Ol root run parts etc cron hourly 02 Aw root rir parts Gtce erom clan ly 22 4 x Q root run parts etc cron weekly 42 41 root run parts etc cron monthly The first four lines are variables used to configure the environment in which the cron tasks are run The SHELL variable tells the system which shell environment to use in this example the bash shell while the patH variable defines the path used to execute commands The output of the cron tasks are emailed to the username defined with the mar To variable If the MAILTO variable is defined as an empty string MATLTo email is not sent The Home variable can be used to set the home directory to use when executing commands or scripts Each line in the etc crontab file represents a task and has the following format 349 Chapter 34 Automated Tasks minute hour day month dayofweek command minute any integer from 0 to 59 hour any integer from 0 to 23 day any integer from 1 to 31 must be a valid d
209. e root privileges and have the system config users RPM package installed To start the User Manager from the desktop go to System on the panel gt Administration gt Users amp Groups You can also type the command system config users at a shell prompt for example in an XTerm or a GNOME terminal File Preferences Help e E 8B amp Add User Add Group Properties Delete Help Refresh Search filter Apply filter User Name User D v Primary Group Full Name Login Shell Home Directory Tammy Fox bin bash home tfox Brent Fox bin bash home bfox Figure 32 1 User Manager 319 Chapter 32 Users and Groups To view a list of local users on the system click the Users tab To view a list of local groups on the system click the Groups tab To find a specific user or group type the first few letters of the name in the Search filter field Press Enter or click the Apply filter button The filtered list is displayed To sort the users or groups click on the column name The users or groups are sorted according to the value of that column Red Hat Enterprise Linux reserves user IDs below 500 for system users By default User Manager does not display system users To view all users including the system users go to Edit gt Preferences and uncheck Hide system users and groups from the dialog box 1 1 Adding a New User To add a new user click the Add User button A window as shown in Figur
210. e server system and read by individual computers during the installation This installation method can support the use of a single kickstart file to install Red Hat Enterprise Linux on multiple machines making it ideal for network and system administrators Kickstart provides a way for users to automate a Red Hat Enterprise Linux installation 2 How Do You Perform a Kickstart Installation Kickstart installations can be performed using a local CD ROM a local hard drive or via NFS FTP or HTTP To use kickstart you must 1 Create a kickstart file 2 Create a boot media with the kickstart file or make the kickstart file available on the network 3 Make the installation tree available 4 Start the kickstart installation This chapter explains these steps in detail 3 Creating the Kickstart File The kickstart file is a simple text file containing a list of items each identified by a keyword You can create it by editing a copy of the sample ks file found in the RH pocs directory of the Red Hat Enterprise Linux Documentation CD using the Kickstart Configurator application or writing it from scratch The Red Hat Enterprise Linux installation program also creates a sample kickstart file based on the options that you selected during installation It is written to the file root anaconda ks cfg You should be able to edit it with any text editor or word processor that can save files as ASCII text First be aware of the followin
211. e subdirectories is displayed in a list The grand total for the current directory and subdirectories are also shown as the last line in the list If you do not want to see the totals for all the subdirectories use the command du hs to see only the grand total for the directory in human readable format Use the du help command to see more options To view the system s partitions and disk space usage in a graphical format use the Gnome System Monitor by clicking on System gt Administration gt System Monitor or type gnome system monitor ata shell prompt such as an XTerm Select the File Systems tab to view the system s partitions The figure below illustrates the File Systems tab Figure 39 3 GNOME System Monitor File Systems 4 Hardware If you are having trouble configuring your hardware or just want to know what hardware is in your system you can use the Hardware Browser application to display the hardware that can be probed To start the program from the desktop select System the main menu on the panel gt Administration gt Hardware or type hwbrowser at a shell prompt As shown in Figure 39 4 Hardware Browser it displays your CD ROM devices diskette drives hard drives and their partitions network devices pointing devices system devices and video cards Click on the category name in the left menu and the information is displayed 384 Hardware Eile CD ROM Drives Selected Device eis lasa LG C
212. e the changes sbin zipl Begin testing the new kernel by rebooting the computer and watching the messages to ensure that the hardware is detected properly 6 4 IBM eServer iSeries Systems The boot vmlinitrd lt kernel version gt file is installed when you upgrade the kernel However you must use the dd command to configure the system to boot the new kernel 1 As root issue the command cat proc iSeries mf side to determine the default side either A B or 2 As root issue the following command where lt kernel version gt is the version of the new kernel and lt side gt is the side from the previous command dd if boot vmlinitrd lt kernel version gt of proc iSeries mf lt side gt vmlinux bs 8k Begin testing the new kernel by rebooting the computer and watching the messages to ensure that the hardware is detected properly 6 5 IBM eServer pSeries Systems IBM eServer pSeries systems use YABOOT as the boot loader which uses etc aboot conf as the configuration file Confirm that the file contains an image section with the same version as the kernel package just installed 368 IBM eServer pSeries Systems Notice that the default is not set to the new kernel The kernel in the first image is booted by default To change the default kernel to boot either move its image stanza so that it is the first one listed or add the directive default and set it to the 1abe1 of the image stanza that contains the
213. e use count The sbin 1smod output is less verbose and easier to read than the output from viewing proc modules To load a kernel module use the sbin modprobe command followed by the kernel module name By default modprobe attempts to load the module from the lib modules lt kernel version gt kernel drivers subdirectories There is a subdirectory for each type of module such as the net subdirectory for network interface drivers Some kernel modules have module dependencies meaning that other modules must be loaded first for it to load The sbin modprobe command checks for these dependencies and loads the module dependencies before loading the specified module For example the command sbin modprobe e100 loads any module dependencies and then the e100 module 372 Persistent Module Loading To print to the screen all commands as sbin modprobe executes them use the v option For example sbin modprobe v e100 Output similar to the following is displayed sbin insmod lib modules 2 6 9 5 EL kernel drivers net e100 ko Using lib modules 2 6 9 5 EL kernel drivers net e100 ko Symbol version prefix smp_ The sbin insmod command also exists to load kernel modules however it does not resolve dependencies Thus it is recommended that the sbin modprobe command be used To unload kernel modules use the sbin rmmod command followed by the module name The rmmod utility only unloads modules that
214. eaees 48 8 l General erminea inaani teh Pall eden al iets tenks 48 8 2 Video Card sssmusessestagersseiauersebvcecssaniaversstuncestanraseeestveceeinsiaadeuteies 49 83 MONMIOI sienevettecceeens Eeee E EENE EEEE RN E EN 50 9 Package Selection ccecccececeeeeceeeeeeeeeeeeae aaa eeeeeeeeeeaeaaaeeeeeeeeeeeaeaaaaees 51 10 Pre Installation Script 22 2 0 ccceceeceeeeeeaeeeeeeeeeeeeeeeaeaaaeeeeeeeeeeeaeaaaaneeeeeees 52 11 Post Installation Script cccceceeeeeeeaeeeeeeeeeeeeeeeaeaaeeteeeeeeeeeaeaaenneeeeeees 54 11 1 Chroot Environment 0 0cccecc cece ce ceeceeeeeeeeeeeeaeaaeeeeeeeeeeeeaeaaaeees 55 11 2 Use an Interpreter 2 0 0 re nrnna inanan ENEA KERE ENNA RAAE EENES 55 t2 Saving the File sisian a aa aa aa 55 3 PXE Network Installations 0 cccccceeeeeeeeeeeeeeeeee sees aa ea eeeeeeeeeeeeaaaaeeeeeeeeeeeeaea 57 1 Setting up the Network Server ccccccccseeeeeeeeeeeeeeaeaeeeeeeeeseeeeaeaaeneeeeeees 57 2 PXE Boot Configuration cccececeeeeeceeeeeeeeeeeeeeeeaaeaeeeeeeeeeeaeaaaaneneeeees 57 2 1 Command Line Configuration cceccceceeeeeeeeeeeeeeeaeeeeeeeeeeeeeeeaea 59 Red Hat Enterprise Linux 4 5 0 So Adding PXE HOSIS siceeiocesiieecetes ERAEN REENEN a 60 3 1 Command Line Configuration sssesesseeeeseeerrsesesesrerrrrrreessrsrrens 61 4 Adding a Custom Boot Message ccceeeeeeeeeeeeeeeaeeeeeeeeeeeeeeeaaeaeeeeeees 62 5 Performing the P
215. ed If only g is specified only group quotas are disabled To enable quotas again use the quotaon command with the same options For example to enable user and group quotas for all file systems use the following command quotaon vaug 129 Chapier 13 Implementing Disk To enable quotas for a specific file system such as home use the following command quotaon vug home If neither the u or g options are specified only the user quotas are enabled If only g is specified only group quotas are enabled 2 2 Reporting on Disk Quotas Creating a disk usage report entails running the repquota utility For example the command repquota home produces this output x Report for user quotas on device dev mapper VolGroup00 LogVol02 Block grace time 7days Inode grace time 7days Block limits File limits User used soft hard grace used soft hard grace root 36 0 0 4 0 0 kristan 540 0 0 125 0 0 testuser 440400 500000 550000 37418 0 0 To view the disk usage report for all option a quota enabled file systems use the command Lepquota 2 While the report is easy to read a few points should be explained The displayed after each user is a quick way to determine whether the block or inode limits have been exceeded If either soft limit is exceeded a appears in place of the corresponding the first represents the block limit and the second represents the inode limit The grace column
216. ed by an option from Table 32 3 chage Command Line Options followed by the username of the user A Important Shadow passwords must be enabled to use the chage command Option Description m lt days gt Specifies the minimum number of days between which the user must change passwords If the value is 0 the password does not expire M lt days gt Specifies the maximum number of days for which the password is valid When the number of days specified by this option plus the number of days specified with the a option is less than the current day the user must change passwords before using the account d lt days gt Specifies the number of days since January 1 1970 the password was changed I lt days gt Specifies the number of inactive days after the password expiration before locking the account If the value is 0 the account is not locked after the password expires E lt date gt Specifies the date on which the account is locked in the format YYYY MM DD Instead of the date the number of days since January 1 1970 can also be used W lt days gt Specifies the number of days before the password expiration date to warn the user 326 Password Aging Table 32 3 chage Command Line Options Tip If the chage command is followed directly by a username with no options it displays the current password aging values and allows them to be changed You can configure a pass
217. ed for consistency by the e2fsck program This is a time consuming process that can delay system boot time significantly especially with large volumes containing a large number of files During this time any data on the volumes is unreachable The journaling provided by the ext3 file system means that this sort of file system check is no longer necessary after an unclean system shutdown The only time a consistency check occurs using ext3 is in certain rare hardware failure cases such as hard drive failures The time to recover an ext3 file system after an unclean system shutdown does not depend on the size of the file system or the number of files rather it depends on the size of the journal used to maintain consistency The default journal size takes about a second to recover depending on the speed of the hardware Data Integrity The ext3 file system provides stronger data integrity in the event that an unclean system shutdown occurs The ext3 file system allows you to choose the type and level of protection that your data receives By default the ext3 volumes are configured to keep a high level of data consistency with regard to the state of the file system Speed Despite writing some data more than once ext3 has a higher throughput in most cases than ext2 because ext3 s journaling optimizes hard drive head motion You can choose from three journaling modes to optimize speed but doing so means trade offs in regards to data integrity E
218. eeaeeeeeeeaaeeeeeeaaeeeeeeaaeeees 361 1 Overview of Kernel Packages cceceeeeeeeeeeeeeeeaeaeeeteeeeeeeeeaeaaeaneeeeees 361 2 Preparing to Upgrade ee ceeceee cece eee eeeeaeeeeeeeaaaeeeeeaaeeeeesaaeeeeeeaaaeees 363 3 Downloading the Upgraded Kernel ceeeeeeeeeeeeeaeeeeeeeeeeeeeeeaeaaeeees 364 4 Performing the Upgrade ce ceeeeeeeee neces ee aeeeeeeeaaeeeeeeaaeeeeeeaaeeeeeaaaeees 365 5 Verifying the Initial RAM Disk Image cccceeeeeeeeeeeeeeeaeeeeeeeeeeeeeeeaes 365 6 Verifying the Boot Loader ccccceeeeeeeeeee esac ea eeeeeeeeeeeeaeaaeaeeeeeeeeeeeeaaa 366 6 1 X86 SYSTEMS essenin aa i a aaia 366 6 2 Itanium Systems ccc cece cece cece eecceeeeeeee tees aeaaeaeeeeeeeeeeaeaaeaneeeeees 367 6 3 IBM S 390 and IBM eServer zSeries Systems eeeeees 367 xii 6 4 IBM eServer iSeries Systems ccceeeeeeeeeeeeeeeeeeeeeeseaaeneeneeeees 368 6 5 IBM eServer pSerieS Systems ccceeeeeeeeeeeeeeeeeeeeeeaaeeteneeeees 368 Sf Kernel MOGUICS rsr cess deecceceaues casdgecdaedsuendeasanecnesdauvnosseaueensenaendabeaneaseedes 371 1 Kernel Module Utilities 22 0 0 cece cece ener cece eee ER 371 2 Persistent Module Loading ccccceeeeeeeneeeeeeeeeeeeeeaaaaeeeeeeeeeeeeaeaaanees 373 3 Additional RESOUrCES senseri ieina Rana EENKEER E ar ANEKA NEERA 374 3 1 Installed Documentation 0 0 cece cece cece eter ee aaeeeeeeaaeeeeeeaaaeees 37
219. eeeeeeeaeaaeeees 300 3 Defining the Console c cccccceeeeeeeeeee cece ae ee eeeeeeeeeeeeaaaaeeeeeeeeeeeeaeaaeeaes 300 4 Making Files Accessible From the Console sneen 301 5 Enabling Console Access for Other Applications c ccceeeeeeeee eee 301 6 The floppy GOUD csssisccssteneecsiwnseeesateyercdanseddcasdeueessabaueccanbayeccaaaeaddcanae 303 28 Date and Time Configuration ccceececeeeeeeeeeeeeeeeeaeeeeeeeeeeeeeeeaaaaeeeeeeeeeeeeaaa 305 1 Time and Date Properties 2 2 0 0 cece cece eeeeeeaeeeeeeeaaeeeeeeaaeeeeeeaaeeeeeeaaaeees 305 2 Network Time Protocol NTP Properties ccceeeeeeeneeeeeeaneeeeeeaaeeees 307 3 Time Zone Configuration ccceeeceeeeeeeceaeeeeeeeeeeeeeeeaaeaeeeeeeeeeeeeaeaaeeees 308 29 Keyboard Configuration ccceceeeeeee ee eeeeeeeeeeeeeeeeaaeaeeeeeeeeeeeeaaaaeeeeeeeeeeeeaaa 311 30 Mouse Configuration 0 cccceceeeeeee cece eee cnet eeeeeeee ee aaeaeeeeeeeeeeeeaaaaeeeeeeeeeeeeaaa 313 31 X Window System Configuration cccececeeeeeeeee ee aeeeeeeeeeeeeeeeaaeaeeeeeeeeeeeaae 315 1 Display Settings ccc ceceee cece cece ee ae aa eee ee sees ee aeaaaaeeeeeeeeeseaaaaeeeeeeees 315 2 Display Hardware Settings 0 cccccceeeeeeeeeeeeeeeeeeeeeeaaaaeeeeeseeeeeeaeaaeaees 316 3 Dual Head Display Settings ecceeeeeeeeeeeeeeeeeeeeeeeeaeaeeeeeeeeeeeeeaeaaaeaes 317 32 Users2and Groups naici innana aaia Tee a anana ta aea
220. efault color depth and resolution Select them from their respective pulldown menus Be sure to specify a color depth and resolution that is compatible with the video card and monitor for the system 48 Video Card File Help Basic Configuration lille Alot id Installation Method L Configure the X Window System Boot Loader Options General Video Card Monitor Partition Information Color Depth Resolution Network Configuration 8 640x480 Authentication 2 Default Desktop GNOME KDE Firewall Configuration Display Configuration C Start the X Window System on boot Package Selection On first boot Setup Agent is Disabled z Pre Installation Script Post Installation Script Figure 2 11 X Configuration General If you are installing both the GNOME and KDE desktops you must choose which desktop should be the default If only one desktop is to be installed be sure to choose it Once the system is installed users can choose which desktop they want to be their default Next choose whether to start the X Window System when the system is booted This option starts the system in runlevel 5 with the graphical login screen After the system is installed this can be changed by modifying the etc inittab configuration file Also select whether to start the Setup Agent the first time the system is rebooted It is disabled by default but the setting can be changed to enabled or enabled in reconfi
221. el downloading 364 large memory support 361 modules 371 multiple processor support 361 upgrading 361 kernel modules etc rc modules 373 listing 371 loading 372 persistent loading 373 unload 373 keyboard configuring 311 Keyboard Configuration Tool 311 keyboards 311 configuration 311 kickstart how the file is found 31 Kickstart Configurator 35 post script 54 pre script 52 authentication options 45 basic options 35 boot loader 39 boot loader options 38 Display configuration 48 firewall configuration 47 installation method selection 36 interactive 36 keyboard 36 language 35 language support 36 mouse 36 network configuration 44 package selection 51 partitioning 40 software RAID 42 preview 35 reboot 36 root password 36 encrypt 36 saving 55 SELinux configuration 48 text mode installation 36 time zone 36 kickstart file include 23 post 27 pre 26 auth 5 authconfig 5 autopart 5 autostep 5 bootloader 8 408 CD ROM based 29 clearpart 8 cmdline 9 creating 4 device 9 diskette based 29 driverdisk 10 firewall 10 firstboot 11 flash based 29 format of 3 halt 11 ignoredisk 5 include contents of another file 23 install 11 installation methods 12 interactive 13 keyboard 13 lang 13 langsupport 13 logvol 14 mouse 14 network 15 network based 30 31 options 4 partitioning examples 24 package selection specification 24 part 16
222. el if you are installing on a brand new hard drive 4 1 Creating Partitions 40 Creating Partitions To create a partition click the Add button The Partition Options window shown in Figure 2 5 Creating Partitions appears Choose the mount point file system type and partition size for the new partition Optionally you can also choose from the following In the Additional Size Options section choose to make the partition a fixed size up to a chosen size or fill the remaining space on the hard drive If you selected swap as the file system type you can select to have the installation program create the swap partition with the recommended size instead of specifying a size Force the partition to be created as a primary partition Create the partition on a specific hard drive For example to make the partition on the first IDE hard disk dev hda specify hda as the drive Do not include dev in the drive name Use an existing partition For example to make the partition on the first partition on the first IDE hard disk dev hda1 specify hda1 as the partition Do not include dev in the partition name Format the partition as the chosen file system type 41 Chapter 2 Kickstart Configurator Mount Point File System Type ext3 Size MB 1 Additional Size Options Fixed size O Grow to maximum of MB O Fill all unused space on disk C Use recommended swap size C Force to be a primary pa
223. ely high cost 2 The storage capacity of the level 1 array is equal to the capacity of one of the mirrored hard disks in a Hardware RAID or one of the mirrored partitions in a Software RAID Level 4 Level 4 uses parity 3 concentrated on a single disk drive to protect data It is better suited to transaction I O rather than large file transfers Because the dedicated parity disk represents an inherent bottleneck level 4 is seldom used without accompanying technologies such as write back caching Although RAID level 4 is an option in some RAID partitioning schemes it is not an option allowed in Red Hat Enterprise Linux RAID installations The storage capacity of Hardware RAID level 4 is equal to the capacity of member disks minus the capacity of one member disk The storage capacity of Software RAID level 4 is equal to the capacity of the member partitions minus the size of one of the partitions if they are of equal size Level 5 This is the most common type of RAID By distributing parity across some or all of an array s member disk drives RAID level 5 eliminates the write bottleneck inherent in level 4 The only performance bottleneck is the parity calculation process With modern CPUs and Software RAID that usually is not a very big problem As with level 4 the result is asymmetrical performance with reads substantially outperforming writes Level 5 is often used with write back caching to reduce the asymmetry The storage capacity of Ha
224. er ID above 500 is assigned to the new user Because Red Hat Enterprise Linux reserves user IDs below 500 for system users it is not advisable to manually assign user IDs 1 499 320 Modifying User Properties Click OK to create the user User Name tfox Full Name Tammy Fox F assWwo rd aininn Confirm Passwo rd saleable Login Shell bin bash Create home directory Home Directory home tfox Create a private group for the user C Specify user 1D manually UID Figure 32 2 New User To configure more advanced user properties such as password expiration modify the user s properties after adding the user Refer to Section 1 2 Modifying User Properties for more information 1 2 Modifying User Properties To view the properties of an existing user click on the Users tab select the user from the user list and click Properties from the menu or choose File gt Properties from the pulldown menu A window similar to Figure 32 3 User Properties appears 321 Chapter 32 Users and Groups User Data Password Info User Name tfox Full Name Tammy Fox Fassword Confirm Password Home Directory ihomeftfox Login Shell bin bash 3 Cancel Figure 32 3 User Properties The User Properties window is divided into multiple tabbed pages e User Data Shows the basic user information configured when you added the user Use this tab to change the user s full name passw
225. er example com and the kickstart file is in the NFS share mydir ks cfg the correct boot command would be ks nfs server example com mydir ks cfg The installation program looks for the kickstart file on the HTTP server lt server gt as file lt path gt The installation program uses DHCP to configure the Ethernet card For example if your HTTP server is server example com and the kickstart file is in the HTTP directory mydir ks cfg the correct boot command would be ks http server example com mydir ks cfg The installation program looks for the file ks cfg on a vfat or ext2 file system on the diskette in dev fdo ks floppy lt path gt The installation program looks for the kickstart file on the diskette in dev fdo as file lt path gt ks hd lt device gt lt file gt The installation program mounts the file system on lt device gt which must be vfat or ext2 and look for the kickstart configuration file as lt file gt in that file system for example ks hd sda3 mydir ks cfg ks file lt file gt The installation program tries to read the file lt file gt from the file system no mounts are done This is normally used if the kickstart file is already on the initrd image 32 Starting a Kickstart Installation ks cdrom lt path gt The installation program looks for the kickstart file on CD ROM as file lt path gt ks If ks is used alone the installation program configures the Ethernet card
226. er from the list and click Edit User To delete an existing Samba user select the user and click the Delete User button Deleting a Samba user does not delete the associated system user account The users are modified immediately after clicking the OK button 2 1 3 Adding a Share To create a Samba share click the Add button from the main Samba configuration window 235 Chapter 22 Samba Basic Access Directory docs project share name docs project Description Shared Docs Project Basic Permissions O Read Write Ja Figure 22 5 Adding a Share The Basic tab configures the following options e Directory The directory to share via Samba The directory must exist before it can be entered here Share name The actual name of the share that is seen from remote machines By default it is the same value as Directory but can be configured e Descriptions A brief description of the share e Basic Permissions Whether users should only be able to read the files in the shared directory or whether they should be able to read and write to the shared directory On the Access tab select whether to allow only specified users to access the share or whether to allow all Samba users to access the share If you select to allow access to specific users select the users from the list of available Samba users The share is added immediately after clicking OK 2 2 Command Line Configuration Samba u
227. er to Table 14 1 Command Line Options for star for a listing of more commonly used options For all available options refer to the star man page The star package is required to use this utility Option Description c Creates an archive file n Do not extract the files use in conjunction with x to show what extracting the files does r Replaces files in the archive The files are written to the end of the archive file replacing any files with the same path and file name t Displays the contents of the archive file u Updates the archive file The files are written to the end of the archive if they do not exist in the archive or if the files are newer than the files of the same name in the archive This option only work if the archive is a file or an unblocked tape that may backspace x Extracts the files from the archive If used with u and a file in the archive is older than the corresponding file on the file system the file is not extracted help Displays the most important options xhelp Displays the least important options Do not strip leading slashes from file names when extracting the files from an archive By default they are 136 Compatibility with Older Systems Option Description striped when files are extracted acl When creating or extracting archive or restore any ACLs associated with the files and directories Table 14 1 C
228. er zSeries timer 1 Table 40 2 OProfile Processors and Counters Use Table 40 2 OProfile Processors and Counters to verify that the correct processor type was detected and to determine the number of events that can be monitored simultaneously timer is used as the processor type if the processor does not have supported performance monitoring hardware If timer is used events cannot be set for any processor because the hardware does not have support for hardware performance counters Instead the timer interrupt is used for profiling If timer is not used as the processor type the events monitored can be changed and counter 0 for the processor is set to a time based event by default If more than one counter exists on the processor the counters other than counter 0 are not set to an event by default The default events monitored are shown in Table 40 3 Default Events Processor Default Event for Counter Description Pentium Pro Pentium CPU_CLK_UNHALTED The processor s clock is not halted Il Pentium IIl Athlon AMD64 Pentium 4 HT and GLOBAL_POWER_EVENTS _ The time during which the processor non HT is not stopped Itanium 2 CPU_CYCLES CPU Cycles TIMER_INT none Sample for each timer interrupt ppc64 power4 CYCLES Processor Cycles ppc64 power5 CYCLES Processor Cycles ppc64 970 CYCLES Processor Cycles Table 40 3 Default Events The number of events that can be monit
229. erchild directive If you check the Allow unlimited requests per connection option the MaxKeepAliveRequests http httpd apache org docs 2 0 mod core html maxkeepaliverequests directive is set to 0 and unlimited requests are allowed If you uncheck the Allow Persistent Connections option the KeepAlive http httpd apache org docs 2 0 mod core html keepalive directive is set to false If you check it the KeepAl ive http httpd apache org docs 2 0 mod core html keepalive directive is set to true and the KeepAliveTimeout http httpd apache org docs 2 0 mod core html keepalivetimeout directive is set to the number that is selected as the Timeout for next Connection value This directive sets the number of seconds your server waits for a subsequent request after a request has been served before it closes the connection Once a request has been received the Connection Timeout value applies instead Setting the Persistent Connections to a high value may cause the server to slow down depending on how many users are trying to connect to it The higher the number the more server processes are waiting for another connection from the last client that connected to it 6 Saving Your Settings If you do not want to save your Apache HTTP Server configuration settings click the Cancel button in the bottom right corner of the HTTP Configuration Tool window You are prompted to confirm this decision If you click Yes to confirm this choice you
230. ernel vmlinuz version ro root dev hda2 initrd initrd version img boot dev hda default 1 timeout 10 splashimage hd0 0 grub splash xpm gz title Red Hat Enterprise Linux 2 6 9 5 EL wero Invel0 kernel vmlinuz 2 6 9 5 EL ro root LABEL miere Linicwed Z 6 9 5 Bil e title Red Hat Enterprise Linux 2 6 9 1 906_EL root hdl 0 kernel vmlinuz 2 6 9 1 906_EL ro root LABEL 366 Itanium Systems Liduitiec aoci rea 6 9 90G IE e If a separate boot partition was created the paths to the kernel and initrd image are relative to boot Notice that the default is not set to the new kernel To configure GRUB to boot the new kernel by default change the value of the default variable to the title section number for the title section that contains the new kernel The count starts with 0 For example if the new kernel is the first title section set default to 0 Begin testing the new kernel by rebooting the computer and watching the messages to ensure that the hardware is detected properly 6 2 Itanium Systems Itanium systems use ELILO as the boot loader which uses poot efi EFI redhat elilo conf as the configuration file Confirm that this file contains an image section with the same version as the kernel package just installed prompt timeout 50 default old image vmlinuz 2 6 9 5 EL label linux Hine eels eel 2 s YS Wilk Win read only append root LA
231. es sbin nologin gopher 13 30 var gopher sbin nologin ftp 14 50 var ftp sbin nologin nobody 99 99 sbin nologin rpm 37 37 var lib rpm sbin nologin vesa 69 69 dev sbin nologin 330 Standard Groups User UID fe B Home Directory Shell dbus 81 81 sbin nologin ntp 38 38 etc ntp sbin nologin canna 39 39 var lib canna sbin nologin nscd 28 28 sbin nologin rpc 32 32 sbin nologin postfix 89 89 var spool postfix sbin nologin mailman 41 41 var mailman sbin nologin named 25 25 var named bin false amanda 33 6 var lib amanda bin bash postgres 26 26 var lib pgsql bin bash exim 93 93 var spool exim sbin nologin sshd 74 74 var empty sshd sbin nologin rpcuser 29 29 var lib nfs sbin nologin nsfnobody 65534 65534 var lib nfs sbin nologin pym 24 24 usr share pvm3 bin bash apache 48 48 var www sbin nologin xfs 43 43 etc X11 fs sbin nologin gdm 42 42 var gdm sbin nologin htt 100 101 usr lib im sbin nologin mysql 27 27 var lib mysql bin bash webalizer 67 67 var www usage sbin nologin mailnull 47 47 var spool mqueue sbin nologin smmsp 51 51 var spool mqueue sbin nologin squid 23 23 var spool squid sbin nologin Idap 55 55 var lib ldap bin false netdump 34 34 var crash bin bash pcap 77 77 var arpwatch sbin nologin radiusd 95 95 oin false radvd 75 75 1 sbin nolo
232. es fix security issues 2 2005 01 12 RHSA 2005 010 Updated VIM packages fix security vulnerability 2 2005 01 05 E RHBA 2004 699 Updated samba packages 2 2005 01 04 E RHBA 2004 700 Updated aspell packages 2 2005 01 04 Q RHSA 2004 651 Updated imlib packages fix security vulnerabilities 2 2004 12 23 Q RHSA 2004 654 Updated SquirrelMail package fixes security vulnerability 2 2004 12 23 ee RHBA 2004 696 Updated BIND packages 2 2004 12 23 MM ucA 30 690 Lindatad kamal nackanar fiv cacuritu uulnarshilitiar 2 2004 12 22 Ka Figure 16 2 Relevant Errata e Automatic email notifications Receive an email notification when an Errata Alert is issued for your system s e Scheduled Errata Updates Schedule delivery of Errata Updates e Package installation Schedule package installation on one or more systems with the click of a button e Package Updater Use the Package Updater to download the latest software packages for your system with optional package installation e Red Hat Network website Manage multiple systems downloaded individual packages and schedule actions such as Errata Updates through a secure Web browser connection from any computer A Caution Cd J You must activate your Red Hat Enterprise Linux product before registering your 156 system with Red Hat Network to make sure your system is entitled to the correct services To activate your product go to After activating your product reg
233. es the LogFormat http httpd apache org docs 2 0 mod mod_log_config html logformat directive Refer to http httpd apache org docs 2 0 mod mod_log_contig htmi formats http httpd apache org docs 2 0 mod mod_log_config html formats for details on the format of this directive The error log contains a list of any server errors that occur Enter the name of the path and file in which to store this information If the path and file name do not start with a slash the path is relative to the server root directory as configured This option corresponds to the ErrorLog 261 Chapter 24 Apache HTTP Serve http httpd apache org docs 2 0 mod core html errorlog directive Use the Log Level menu to set the verbosity of the error messages in the error logs It can be set from least verbose to most verbose to emerg alert crit error warn notice info or debug This option corresponds to the LogLhevel http httpd apache org docs 2 0 mod core html loglevel directive The value chosen with the Reverse DNS Lookup menu defines the HostnameLookups http httpd apache org docs 2 0 mod core html hostnamelookups directive Choosing No Reverse Lookup sets the value to off Choosing Reverse Lookup sets the value to on Choosing Double Reverse Lookup sets the value to double If you choose Reverse Lookup your server automatically resolves the IP address for each connection which requests a document from your Web server Resolving the I
234. ess device To add a wireless Ethernet connection follow these steps 1 Click the Devices tab 2 Click the New button on the toolbar 3 Select Wireless connection from the Device Type list and click Forward 4 If you have already added the wireless network interface card to the hardware list select it from the Wireless card list Otherwise select Other Wireless Card to add the hardware device Note The installation program usually detects supported wireless Ethernet devices and prompts you to configure them If you configured them during the installation they are displayed in the hardware list on the Hardware tab 5 If you selected Other Wireless Card the Select Ethernet Adapter window appears Select the manufacturer and model of the Ethernet card and the device If this is the first Ethernet card for the system select ethO if this is the second Ethernet card for the system select eth1 and so on The Network Administration Tool also allows the user to configure the resources for the wireless network interface card Click Forward to continue 6 On the Configure Wireless Connection page as shown in Figure 17 12 Wireless Settings configure the settings for the wireless device 176 Establishing a Wireless Connection Configure Wireless Connection Mode Auto Network Name SSID A o Specified Channel Transmit Rate Key use Ox for hex
235. essary to list the desired groups and not individual packages Note that the core and Base groups are always selected by default so it is not necessary to specify them in the packages section Here is an example packages selection Spackages X Window System GNOME Desktop Environment Graphical Internet Sound and Video dhcp As you Can see groups are specified one to a line starting with an e symbol a space and then the full group name as given in the comps xm1 file Groups can also be specified using the id for the group such as gnome desktop Specify individual packages with no additional characters the dhcp line in the example above is an individual package You can also specify which packages not to install from the default package list autofs The following options are available for the packages option resolvedeps Install the listed packages and automatically resolve package dependencies If this option is not specified and there are package dependencies the automated installation pauses and prompts the user For example Spackages resolvedeps ignoredeps Ignore the unresolved dependencies and install the listed packages without the dependencies For example Spackages ignoredeps ignoremissing Ignore the missing packages and groups instead of halting the installation to ask if the installation should be aborted or continued For example Spackages ignoremissing 25 C
236. estingCommon Name your name or server s hostname test example comEmail Address admin example comPleas nter the following extra attributes to be sent with your certificate request A challenge password An optional company name The default answers appear in brackets immediately after each request for input For example the first information required is the name of the country where the certificate is to be used shown like the following Country Name 2 letter code GB The default input in brackets is cB Accept the default by pressing Enter or fill in your country s two letter code 283 Chapter 25 Apache HTTP Secur You have to type in the rest of the values All of these should be self explanatory but you must follow these guidelines Do not abbreviate the locality or state Write them out for example St Louis should be written out as Saint Louis If you are sending this CSR to a CA be very careful to provide correct information for all of the fields but especially for the organization Name and the Common Name CAs check the information provided in the CSR to determine whether your organization is responsible for what you provided as the common Name CAs rejects CSRs which include information they perceive as invalid For Common Name make sure you type in the rea name of your secure server a valid DNS name and not any aliases which the server may have e The Email A
237. evel 2 8 1 1 1386 rpm HelixPlayer 1 0 1 gold 8EL i386 rpm ImageMagick 6 0 7 1 5 i386 rpm mageMagick c 6 0 7 1 5 i386 rpm ImageMagick c devel 6 0 7 1 5 i386 rpm ImageMagick devel 6 0 7 1 5 i386 rpm nanma minnn X Org X11 Log Filter for Filter i Reset Figure 35 1 Log Viewer By default the currently viewable log file is refreshed every 30 seconds To change the refresh rate select Edit gt Preferences from the pulldown menu The window shown in Figure 35 2 Log File Locations appears In the Log Files tab click the up and down arrows beside the refresh rate to change it Click Close to return to the main window The refresh rate is changed immediately To refresh the currently viewable file manually select File gt Refresh Now or press Ctrl R On the Log Files tab in the Preferences the log file locations can be modified Select the log file from the list and click the Edit button Type the new location of the log file or click the Browse button to locate the file location using a file selection dialog Click OK to return to the preferences and click Close to return to the main window 356 Adding a Log File Log Files X Configure the path and filename for each log file displayed oare femm JA Boot Log var log boot log Cron Log var log cron Kernel Startup Log var log dmesg Mail Log var log maillog MySQL Server Log var log mysqld log News Log var log spooler RPM Packages var
238. evel you are currently editing To edit a different runlevel select Edit Runlevel from the pulldown menu and select runlevel 3 4 or 5 Refer to Section 1 Runlevels for a description of runlevels The Services Configuration Tool lists the services from the etc rc d init d directory as well as the services controlled by xineta Click on the name of the service from the list on the left hand side of the application to display a brief description of that service as well as the status of the service If the service is not an xineta service the status window shows whether the service is currently running If the service is controlled by xineta the status window displays the phrase xinetd service To start stop or restart a service immediately select the service from the list and click the 208 Services Configuration Tool appropriate button on the toolbar or choose the action from the Actions pulldown menu If the service is an xinetd service the action buttons are disabled because they can not be started or stopped individually If you enable disable an xinetd service by checking or unchecking the checkbox next to the service name you must select File gt Save Changes from the pulldown menu to restart xinetd and immediately enable disable the xinetd service that you changed xinetd is also configured to remember the setting You can enable disable multiple xinetd services at a time and save the changes when you are finished
239. evices and Mount Points Once you have all of your partitions created as software RAID partitions the following steps create the RAID device and mount point 1 Select the RAID button on the Disk Druid main partitioning screen refer to Figure 10 5 RAID Options 2 Figure 10 5 RAID Options appears Select Create a RAID device 103 Chapter 10 Software RAID Con RAID Options Software RAID allows you to combine several disks into a larger RAID device A RAID device can be confiqured to provide additional speed and reliability compared to using an individual drive For more information on using RAID devices please consult the Red Hat Enterprise Linux AS documentation You currently have 3 software RAID partition s free to use What do you want to do now O Create a software RAID partition O Clone a drive to create a RAID device default dev md0 Figure 10 5 RAID Options 3 Next Figure 10 6 Making a RAID Device and Assigning a Mount Point appears where you can make a RAID device and assign a mount point 104 Points Make RAID Device Mount Point bo File System Type ext3 RAID Device mdQ RAID Level RAIDO sdal 102 MB RAID Members sdbl 102 MB Number of spares Jo Figure 10 6 Making a RAID Device and Assigning a Mount Point Enter a mount point Choose the file system type for the partition At this point you can either config
240. ew Go Bookmarks Help q q gt AOGA A Back Forward Up Stop Reload Home Location smb T ag ag Lite G fo ARTSTUFF MINE MY GROUP mn HU WORKGROUP WORKGROUP selected 0 bytes Figure 22 6 SMB Workgroups in Nautilus r 7 100 Viewas Icons Ute REDHAT Double click one of the workgroup icons to view a list of computers within the workgroup 240 Command Line File Edit View Go Bookmarks Help qd gt AOGA A Back Forward Up Stop Reload Home Location smb workgroup 100 Viewas icons FALCON PIGDOG PINKY YETI WORKGROUP selected 0 bytes Figure 22 7 SMB Machines in Nautilus As you can see from Figure 22 7 SMB Machines in Nautilus there is an icon for each machine within the workgroup Double click on an icon to view the Samba shares on the machine If a username and password combination is required you are prompted for them Alternately you can also specify the Samba server and sharename in the Location bar for Nautilus using the following syntax replace lt servername gt and lt sharename gt with the appropriate values smb lt servername gt lt sharename gt 3 1 Command Line To query the network for Samba servers use the findsmb command For each server found it displays its IP address NetBIOS name workgroup name operating system and SMB server version To connect to a Samba share from a shell pro
241. f a large number of systems Instead of reconfiguring all the systems he can just edit one DHCP configuration file on the server for the new set of IP addresses If the DNS servers for an organization changes the changes are made on the DHCP server not on the DHCP clients Once the network is restarted on the clients or the clients are rebooted the changes take effect Furthermore if a laptop or any type of mobile computer is configured for DHCP it can be moved from office to office without being reconfigured as long as each office has a DHCP server that allows it to connect to the network 2 Configuring a DHCP Server To configure a DHCP server the etc dhcpd conf configuration file must be created A sample file can be found at usr share doc dhcp lt version gt dhcpd conf sample DHCP also uses the file var 1lib dhcp dhcpd leases to store the client lease database Refer to Section 2 2 Lease Database for more information 2 1 Configuration File The first step in configuring a DHCP server is to create the configuration file that stores the network information for the clients Global options can be declared for all clients while other options can be declared for individual client systems The configuration file can contain extra tabs or blank lines for easier formatting Keywords are case insensitive and lines beginning with a hash mark are considered comments Two DNS update schemes are currently implemented th
242. fault targeted policy being enforced Note If the selinux option is not present in the kickstart file SELinux is enabled and set to enforcing by default permissive Outputs warnings only based on the SELinux policy but does not actually enforce the policy disabled Disables SELinux completely on the system For complete information regarding SELinux for Red Hat Enterprise Linux refer to the Red Hat SELinux Guide shutdown optional Shut down the system after the installation has successfully completed During a kickstart installation if no completion method is specified the reboot option is used as default The shutdown option is roughly equivalent to the shutdown command For other completion methods refer to the halt poweroff and reboot kickstart options skipx optional If present X is not configured on the installed system text optional Perform the kickstart installation in text mode Kickstart installations are performed in graphical mode by default timezone required Sets the system time zone to lt timezone gt which may be any of the time zones listed by timeconfig timezone utc lt timezone gt 21 Chapter 1 Kickstart Installa lt If present the system assumes the hardware clock is set to UTC Greenwich Mean time upgrade optional Tells the system to upgrade an existing system rather than install a fresh system You must specify one of cdrom harddrive
243. for more than 4 GB of RAM up to 16 GB for x86 PAE Physical Address Extension or 3 level paging on x86 processors that support PAE kernel smp devel Contains the kernel headers and makefiles sufficient to build modules against the kernel smp package kernel utils Contains utilities that can be used to control the kernel or system hardware kernel doc Contains documentation files from the kernel source Various portions of the Linux kernel and the device drivers shipped with it are documented in these files Installation of this package provides a reference to the options that can be passed to Linux kernel modules at load time By default these files are placed in the usr share doc kernel doc lt version gt directory Note The kernel source package has been removed and replaced with an RPM that can only be retrieved from Red Hat Network This src rpm must then be rebuilt locally using the rpmbuild command Refer to the latest distribution 362 Preparing to Upgrade Release Notes including all updates at https www redhat com docs manuals enterprise for more information on obtaining and installing the kernel source package 2 Preparing to Upgrade Before upgrading the kernel take a few precautionary steps The first step is to make sure working boot media exists for the system in case a problem occurs If the boot loader is not configured properly to boot the new kernel the system can
244. from the pulldown menu To view the list of print jobs in the print spool from a shell prompt type the command 1pq The last few lines look similar to the following Rank Owner ID Class Job Files Size Time active user localhost 902 A 902 sample txt 2050 01 20 46 Example 33 1 Example of 1pq output If you want to cancel a print job find the job number of the request with the command 1pq and then use the command 1prm job number For example lprm 902 would cancel the print job in Example 33 1 Example of 1pq output You must have proper permissions to cancel a print job You can not cancel print jobs that were started by other users unless you are logged in as root on the machine to which the printer is attached You can also print a file directly from a shell prompt For example the command ipr sample txt prints the text file sample txt The print filter determines what type of file it is and converts it into a format the printer can understand 9 Additional Resources To learn more about printing on Red Hat Enterprise Linux refer to the following resources 346 Useful Websites 9 1 Installed Documentation map lpr The manual page for the 1pr command that allows you to print files from the command line man lprm The manual page for the command line utility to remove print jobs from the print queue man mpage The manual page for the command line utility to print multiple pages on one sheet of paper
245. fter changing any of the options save them by clicking the Save and quit button The preferences are written to root oprofile daemonrc and the application exits Exiting the application does not stop OProfile from sampling On the Setup tab to set events for the processor counters as discussed in Section 2 2 Setting Events to Monitor select the counter from the pulldown menu and select the event from the list A brief description of the event appears in the text box below the list Only events available for the specific counter and the specific architecture are displayed The interface also displays whether the profiler is running and some brief statistics about it 399 Chapter 40 OProfile Configuration Counter 0 BUS_DRDY_CLOCKS v Counter settings Enabled Event L2_DBUS_BUSY L2_DBUS_BUSY_RD BUS_DRDY_CLOCKS BUS_LOCK_CLOCKS BUS_REQ_OUTSTANDING BUS_TRAN_BRD BUS_TRAN_RFO BUS_TRANS_WB BUS_TRAN_IFETCH BUS_TRAN_INVAL BUS_TRAN_BURST BUS_TRAN_ANY BUS_TRAN_MEM BUS_DATA_RCV MISALIGN_MEM_REF EMON_KNI_PREF_DISPATCHED FMON KNI PREF MISS Z Profile kernel Profile user binaries Count 397952 Unit mask C self generated transactions any transactions Lv bus cycles this processor is driving HIT pin Profiler running O hours 59 mins 29 interrupts second total 49471 start potter Flush profiler data Stop profiler Save and quit 400 Graphical Interface
246. g Verifying a package compares information about files installed from a package with the same information from the original package Among other things verifying compares the size MD5 sum permissions type owner and group of each file The command rpm v verifies a package You can use any of the Package Verify Options listed for querying to specify the packages you wish to verify A simple use of verifying is rpm v foo which verifies that all the files in the foo package are as they were when they were originally installed For example 148 Checking a Package s Signature e To verify a package containing a particular file rpm Vf usr bin vim e To verify ALL installed packages rpm Va e To verify an installed package against an RPM package file Ro Wid LOO 1L O 1 1386 rom This command can be useful if you suspect that your RPM databases are corrupt If everything verified properly there is no output If there are any discrepancies they are displayed The format of the output is a string of eight characters a c denotes a configuration file and then the file name Each of the eight characters denotes the result of a comparison of one attribute of the file to the value of that attribute recorded in the RPM database A single period means the test passed The following characters denote failure of certain tests e 5 MD5 checksum e s file size L symbolic link e T file modification t
247. g which masks requests from LAN nodes with the IP address of the firewall s external device in this case ethO root myServer iptables t nat A POSTROUTING o eth0O j MASQUERADE This rule uses the NAT packet matching table t nat and specifies the built in POSTROUTING chain for NAT A PosTROUTING on the firewall s external networking device o eth POSTROUTING allows packets to be altered as they are leaving the firewall s external device The j MASQUERADE target is specified to mask the private IP address of a node with the external IP address of the firewall gateway 5 2 Prerouting If you have a server on your internal network that you want make available externally you can use the j DNAT target of the PREROUTING chain in NAT to specify a destination IP address and port where incoming packets requesting a connection to your internal service can be forwarded For example if you want to forward incoming HTTP requests to your dedicated Apache HTTP Server at 172 31 0 23 use the following command root myServer iptables t nat A PREROUTING i eth0 p tcp dport 80 4 DMAW Sc0 172 3150 23280 This rule specifies that the nat table use the built in PREROUTING chain to forward incoming HTTP requests exclusively to the listed destination IP address of 172 31 0 23 200 DMZs and IPTables Note If you have a default policy of DROP in your FORWARD chain you must append
248. g into a computer locally they are given two types of special permissions 1 They can run certain programs that they would not otherwise be able to run 2 They can access certain files normally special device files used to access diskettes CD ROMs and so on that they would not otherwise be able to access Since there are multiple consoles on a single computer and multiple users can be logged into the computer locally at the same time one of the users has to essentially win the race to access the files The first user to log in at the console owns those files Once the first user logs out the next user who logs in owns the files In contrast every user who logs in at the console is allowed to run programs that accomplish tasks normally restricted to the root user If X is running these actions can be included as menu items in a graphical user interface As shipped the console accessible programs include halt poweroff and reboot 1 Disabling Shutdown Via Ctrl Alt Del By default etc inittab specifies that your system is set to shutdown and reboot in response to a Cirl Alt Del key combination used at the console To completely disable this ability comment out the following line in etc inittab by putting a hash mark in front of it Ga ctrlaltdel sbin shutdown t3 A now Alternatively you may want to allow certain non root users the right to shutdown or reboot the system from the console using Ctrl Alt Del You can restr
249. g issues when you are creating your kickstart file Chapter 1 Kickstart Installa e Sections must be specified in order Items within the sections do not have to be in a specific order unless otherwise specified The section order is e Command section Refer to Section 4 Kickstart Options for a list of kickstart options You must include the required options e The packages section Refer to Section 5 Package Selection for details e The spre and post sections These two sections can be in any order and are not required Refer to Section 6 Pre installation Script and Section 7 Post installation Script for details Items that are not required can be omitted Omitting any required item results in the installation program prompting the user for an answer to the related item just as the user would be prompted during a typical installation Once the answer is given the installation continues unattended unless it finds another missing item Lines starting with a pound sign are treated as comments and are ignored For kickstart upgrades the following items are required e Language Language support Installation method e Device specification if device is needed to perform the installation e Keyboard setup e The upgrade keyword e Boot loader configuration If any other items are specified for an upgrade those items are ignored note that this includes package selection
250. gin quagga 92 92 var run quagga sbin login wnn 49 49 var lib wnn sbin nologin dovecot 97 97 usr libexec dovecot sbin nologin Table 32 4 Standard Users 331 Chapter 32 Users and Groups 4 Standard Groups Table 32 5 Standard Groups lists the standard groups configured by an Everything installation Groups are stored in the etc group file Group ej iB Members root 0 root bin 1 root bin daemon daemon 2 root bin daemon sys 3 root bin adm adm 4 root adm daemon tty 5 disk 6 root Ip 7 daemon Ip mem 8 kmem 9 wheel 10 root mail 12 mail postfix exim news 13 news uucp 14 uucp man 15 games 20 gopher 30 dip 40 ftp 50 lock 54 nobody 99 users 100 rpm 37 utmp 22 floppy 19 vesa 69 dbus 81 ntp 38 canna 39 nscd 28 rpc 32 332 User Private Groups Group fe B Members posidrop 90 postfix 89 mailman 41 exim 93 named 25 postgres 26 sshd 74 rpcuser 29 nfsnobody 65534 pym 24 apache 48 xfs 43 gdm 42 htt 101 mysql 27 webalizer 67 mailnull 47 smmsp 51 squid 23 Idap 55 netdump 34 pcap 77 quaggavt 102 quagga 92 radvd 75 slocate 21 wnn 49 dovecot 97 radiusd 95 Table 32 5 Standard Groups 5 User Private Groups Red Hat Enter
251. gs The DNS tab allows you to configure the system s hostname domain name servers and search domain Name servers are used to look up other hosts on the network 178 Managing DNS Settings If the DNS server names are retrieved from DHCP or PPPoE or retrieved from the ISP do not add primary secondary or tertiary DNS servers If the hostname is retrieved dynamically from DHCP or PPPoE or retrieved from the ISP do not change it File Profile Help Copy Delete You may E the system s hostname domain name servers and search domain Name servers are used to look up other hosts on the network Hostname localhost localdom airl Primary DNS 172 16 52 28 Figure 17 14 DNS Configuration Note The name servers section does not configure the system to be a name server Instead it configures which name servers to use when resolving IP addresses to hostnames and vice versa 179 Chapter 17 Network Configuration Warning If the hostname is changed and system config network is started on the local host you may not be able to start another X11 application As such you may have to re login to a new desktop session 9 Managing Hosts The Hosts tab allows you to add edit or remove hosts from the etc hosts file This file contains IP addresses and their corresponding hostnames When your system tries to resolve a hostname to an IP address or tries to determine the hostname for a
252. gt lt version gt lt arch gt rpm where lt variant gt IS smp utils Or SO forth The lt arch gt is one of the following x86_64 for the AMD64 architecture ia 4 for the Intel ltanium architecture ppc 4 for the IBM eServer pSeries architecture ppc 4 for the IBM eServer iSeries architecture s390 for the IBM S 390 architecture s390x for the IBM eServer zSeries architecture x86 variant The x86 kernels are optimized for different x86 versions The options are as follows e i686 for Intel Pentium Il Intel Pentium Ill Intel Pentium 4 AMD Athlon and AMD Duron systems 3 Downloading the Upgraded Kernel There are several ways to determine if an updated kernel is available for the system Security Errata Go to the following location for information on security errata including kernel upgrades that fix security issues http www redhat com apps support errata Via Quarterly Updates Refer to the following location for details http www redhat com apps support errata rhlas_errata_policy html Via Red Hat Network Download and install the kernel RPM packages Red Hat Network can download the latest kernel upgrade the kernel on the system create an initial RAM disk image if needed and configure the boot loader to boot the new kernel For more information refer to http www redhat com docs manuals RHNetwork http www redhat com docs manuals RHNetwork If Red Hat Ne
253. guration Select the new mouse type for the system If the specific mouse model is not listed select one of the Generic entries based on the mouse s number of buttons and its interface If there is not an exact match select the generic match that is most compatible with the system and the mouse Tip Select the Generic Wheel Mouse entry with the proper mouse port to enable the scroll button on the mouse The scroll button on a wheel mouse can be used as the middle mouse button for cutting text pasting text and other middle mouse button functions If the mouse only has two buttons select Emulate 3 buttons to use a two button mouse as a three button mouse When this option enabled clicking the two mouse buttons simultaneously emulates a middle mouse button click If a serial port mouse is selected click the Serial devices button to configure the correct serial device number such as dev ttyso for the mouse Click OK to save the new mouse type The selection is written to the file etc sysconfig mouse and the console mouse service gpm is restarted The changes are also written to the X Window System configuration file etc xX11 xorg conf however the mouse type change is not automatically applied to the current X session To enable the new mouse type log out of the graphical desktop and log back in Tip To reset the order of the mouse buttons for a left handed user go to Applications the main menu on the panel gt Prefe
254. guration mode Reconfiguration mode enables the language mouse keyboard root password security level time zone and networking configuration options in addition to the default ones 8 2 Video Card Probe for video card is selected by default Accept this default to have the installation program 49 Chapter 2 Kickstart Configurator probe for the video card during installation Probing works for most modern video cards If this option is selected and the installation program cannot successfully probe the video card the installation program stops at the video card configuration screen To continue the installation process select your video card from the list and click Next Alternatively you can select the video card from the list on the Video Card tab as shown in Figure 2 12 X Configuration Video Card Specify the amount of video RAM the selected video card has from the Video Card RAM pulldown menu These values are used by the installation program to configure the X Window System Eile Help Basic Configuration Display Configuration Installation Method Configure the X Window System Boot Loader Options General Video Card Partition Information BE ai Network Configuration E Authentication Matrox Comet Firewall Configuration Matrox Marvel II Matrox Millennium Package Selection Matrox Millennium G200 Pre Instalation Script Post Installation Script Matrox Millennium G450 Matrox Millennium G550 Matrox Mille
255. gure 33 8 Settings Tab 7 2 The Policies Tab 344 The Access Control Tab To change settings in print output click the Policies tab For example to create a banner page a page that describes aspects of the print job such as the originating printer the username from the which the job originated and the security status of the document being printed click the Starting Banner or Ending Banner drop menu and choose the option that best describes the nature of the print jobs such as topsecret classified or confidential Figure 33 9 Policies Tab You can also configure the Error Policy of the printer by choosing an option from the drop down menu You can choose to abort the print job retry or stop it 7 3 The Access Control Tab You can change user level access to the configured printer by clicking the Access Control tab Add users using the text box and click the Add button beside it You can then choose to only allow use of the printer to that subset of users or deny use to those users Figure 33 10 Access Control Tab 7 4 The Printer and Job OptionsTab The Printer Options tab contains various configuration options for the printer media and output Figure 33 11 Printer Options Tab Page Size Allows the paper size to be selected The options include US Letter US Legal A3 and A4 Media Source set to Automatic by default Change this option to use paper from a different tray Media Type Allows
256. h as installing additional software and configuring an additional nameserver Note If you configured the network with static IP information including a nameserver you can access the network and resolve IP addresses in the post section If you configured the network for DHCP the etc resolv conf file has not been 27 Chapier 1 Kickstart Installa completed when the installation executes the spost section You can access the network but you can not resolve IP addresses Thus if you are using DHCP you must specify IP addresses in the post section Note The post install script is run in a chroot environment therefore performing tasks such as copying scripts or RPMs from the installation media do not work nochroot Allows you to specify commands that you would like to run outside of the chroot environment The following example copies the file etc resolv conf to the file system that was just installed Spost nochroot cp etc resolv conf mnt sysimage etc resolv conf interpreter usr bin python Allows you to specify a different scripting language such as Python Replace usr bin python with the scripting language of your choice 7 1 Examples Turn services on and off sbin chkconfig level 345 telnet off sbin chkconfig level 345 finger Otte isbunjchkcontuigqu lcviclles4 belo dwotin soumichcontigu levclme4 Smiter cmon Run a script named runme from an NFS share mkdir mnt temp
257. h command when you run a program on the remote machine that requires X it will be displayed on your local machine This feature is convenient if you prefer graphical system administration tools but do not always have physical access to your server 2 Configuring an OpenSSH Server To run an OpenSSH server you must first make sure that you have the proper RPM packages installed The openssh server package is required and depends on the openssh package The OpenSSH daemon uses the configuration file etc ssh sshd_config The default configuration file should be sufficient for most purposes If you want to configure the daemon in ways not provided by the default sshd_config read the sshd man page for a list of the keywords that can be defined in the configuration file To start the OpenSSH service use the command sbin service sshd start To stop the OpenSSH server use the command sbin service sshd stop If you want the daemon to start automatically at boot time refer to Chapter 19 Controlling Access to Services for information on how to manage services If you reinstall the reinstalled system creates a new set of identification keys Any clients who had connected to the system with any of the OpenSSH tools before the reinstall will see the following message CAR ECEAERECEEERERECEEEREEECEEEREEEEEEREEEEEEREEEEEEREEEEREEEEEE WARNING REMOTE HOST IDENTIFICATION HAS CHANGED CERECEEEERECEREEEEEEREEECEEEREEEEEEEEEEEEEEEEEEEEREEEEREEEEEE
258. h the default policy to define the overall ruleset for the firewall The default policy for a chain can be either DROP or ACCEPT Security minded administrators typically implement a default policy of DROP and only allow specific packets on a case by case basis For example the following policies block all incoming and outgoing packets on a network gateway root myServer iptables P INPUT DROP root myServer iptables P OUTPUT DROP It is also recommended that any forwarded packets network traffic that is to be routed from the firewall to its destination node be denied as well to restrict internal clients from inadvertent exposure to the Internet To do this use the following rule root myServer iptables P FORWARD DROP When you have established the default policies for each chain you can create and save further rules for your particular network and security requirements The following sections describe how to save iptables rules and outline some of the rules you might implement in the course of building your iptables firewall 3 3 Saving and Restoring IPTables Rules 196 Common IPTables Filtering Changes to iptables are transitory if the system is rebooted or if the iptables service is restarted the rules are automatically flushed and reset To save the rules so that they are loaded when the iptables service is started use the following command root myServer service iptables save T
259. hapter 1 Kickstart Installa 6 Pre installation Script You can add commands to run on the system immediately after the ks cfg has been parsed This section must be at the end of the kickstart file after the commands and must start with the pre Command You can access the network in the pre section however name service has not been configured at this point so only IP addresses work Note Note that the pre install script is not run in the change root environment interpreter usr bin python Allows you to specify a different scripting language such as Python Replace usr bin python with the scripting language of your choice 6 1 Example Here is an example spre section Spre bin sh hds mymedia for file in proc ide h do mymedia cat file media if Smymedia disk then hds hds basename file T done set hds numhd echo cheiwyeil eciao Sincls uic el YU iil Chaye2 eclang Sincls uic cl Y i2 Write out partition scheme based on whether there are 1 or 2 hard drives if Snumhd 2 then 2 drives echo partitioning scheme generated in pre for 2 drives gt tmp part include echo clearpart all gt gt tmp part include eChom oars Oo ois fstyp SES size 75 ondisk hda gt gt 26 Post installation Script tmp part include acboa Yoare fstype ext3 size 1 grow ondisk hda gt gt tmp part include
260. hapter 8 LVM Configuration Disk Setup Choose where you would like Red Hat Enterprise Linux AS to be installed If you do not know how to partition your system or if you need help with using the manual partitioning tools refer to the product documentation If you used automatic partitioning you can either accept the current partition settings click Next or modify the setup using the manual partitioning tool If you are manually partitioning your system you can see your current hard drive s and partitions displayed below Use Guide Help Release Notes zi Drive dev sda 8676 MB Model IBM PSG ST39103LC dFree 8573 MB Drive dev sdb 8676 MB Model IBM PSG ST39204LC Free 8678 MB Edit Delete Reset RAID LVM Mount Point Size Hard Drives V dev sda dev sda boot ext3 102 1 B Free Free space 8574 14 1106 V dev sdb Free Free space 8679 1 1107 C Hide RAID device LVM Volume Group members Figure 8 4 The boot Partition Displayed 2 2 Creating the LVM Physical Volumes Once the boot partition is created the remainder of all disk space can be allocated to LVM partitions The first step in creating a successful LVM implementation is the creation of the physical volume s 1 Select New 2 Select physical volume LVM from the File System Type pulldown menu as shown in Figure 8 5 Creating a Physical Volume
261. hapter 8 LVM Configuration example if you want the volume group to span over more than one drive create a physical volume on each of the drives The following figure shows both drives completed after the repeated process gt Disk Setup Choose where you would like Red Hat Enterprise Linux AS to be installed If you do not know how to partition your system or if you need help with using the manual partitioning tools refer to the product documentation If you used automatic partitioning you can either accept the current partition settings click Next or modify the setup using the manual partitioning tool If you are manually partitioning your system you can see your current hard drive s and partitions displayed below Use Hide Help Release Notes Drive dev sda 8676 MB Model IBM PSG ST39103LC dsda2 8573 MB Drive dev sdb 8676 MB Model IBM PSG ST39204LC sdb1 8675 MB EA ae Delete Reset PAT ive Mount Point Size RAID Volume YP Format yp Hard Drives V dev sda dev sdal boot ext3 102 1 13 dev sda2 LVMPV 8574 14 1106 VY dev sdb dev sdb1 LVMPV 8676 1 1106 i CI Hide RAID device LVM Volume Group members lt amp Back gt Next Figure 8 6 Two Physical Volumes Created 2 3 Creating the LVM Volume Groups Once all the physical volumes are created the volume groups can be created 1 Click the LVM bu
262. he Network Configuration section are listed as available Trusted devices Connections from any devices selected in the list are accepted by the system For example if eth1 only receives connections from internal system you might want to allow connections from it If a service is selected in the Trusted services list connections for the service are accepted and processed by the system In the Other ports text field list any additional ports that should be opened for remote access Use the following format port protocol For example to allow IMAP access through the firewall specify imap tcp Specify numeric ports can also be specified to allow UDP packets on port 1234 through the firewall enter 1234 udp To specify multiple ports separate them with commas 7 1 SELinux Configuration Although configuration for SELinux is not specified in the Kickstart Configurator kickstart enables SELinux in enforcing mode by default if the selinux parameter is omitted from the kickstart file 8 Display Configuration If you are installing the X Window System you can configure it during the kickstart installation by checking the Configure the X Window System option on the Display Configuration window as shown in Figure 2 11 X Configuration General If this option is not chosen the X configuration options are disabled and the skipx option is written to the kickstart file 8 1 General The first step in configuring X is to choose the d
263. he command system config nfs 224 Exporting NFS File Systems File Help fo cA L 8 Add Properties Delete Help Directory Hosts Permissions Figure 21 1 NFS Server Configuration Tool To add an NFS share click the Add button The dialog box shown in Figure 21 2 Add Share appears The Basic tab requires the following information e Directory Specify the directory to share such as tmp e Host s Specify the host s with which to share the directory Refer to Section 3 2 Hostname Formats for an explanation of possible formats e Basic permissions Specify whether the directory should have read only or read write permissions Basic General Options User Access Directory tmp Hostis example com Basic permissions Read only C Read Write Figure 21 2 Add Share 225 Chapter 21 Network File Syst The General Options tab allows the following options to be configured Allow connections from port 1024 and higher Services started on port numbers less than 1024 must be started as root Select this option to allow the NFS service to be started by a user other than root This option corresponds to insecure Allow insecure file locking Do not require a lock request This option corresponds to insecure_locks Disable subtree checking If a subdirectory of a file system is exported but the entire file system is not exported
264. he rules are stored in the file etc sysconfig iptables and are applied whenever the service is started or the machine is rebooted 4 Common IPTables Filtering Preventing remote attackers from accessing a LAN is one of the most important aspects of network security The integrity of a LAN should be protected from malicious remote users through the use of stringent firewall rules However with a default policy set to block all incoming outgoing and forwarded packets it is impossible for the firewall gateway and internal LAN users to communicate with each other or with external resources To allow users to perform network related functions and to use networking applications administrators must open certain ports for communication For example to allow access to port 80 on the firewall append the following rule root myServer iptables A INPUT p tcp m tcp dport 80 7 ACCEPT This allows users to browse websites that communicate using the standard port 80 To allow access to secure websites for example https www example com you also need to provide access to port 443 as follows root myServer iptables A INPUT p tcp m tcp dport 443 j ACCEPT Important When creating an iptables ruleset order is important If a rule specifies that any packets from the 192 168 100 0 24 subnet be dropped and this is followed by a rule that allows packets from 192 168 100 13 which is within the dropped su
265. he world read write access Each time you change etc exports you must inform the NFS daemon of the change or reload the configuration file with the following command sbin service nfs reload 3 2 Hostname Formats The host s can be in the following forms Single machine A fully qualified domain name that can be resolved by the server hostname that can be resolved by the server or an IP address Series of machines specified with wildcards Use the or character to specify a string match Wildcards are not to be used with IP addresses however they may accidentally work if reverse DNS lookups fail When specifying wildcards in fully qualified domain names dots are not included in the wildcard For example example com includes one example com but does not include one two example com IP networks Use a b c d z where a b c dis the network and z is the number of bits in the netmask for example 192 168 0 0 24 Another acceptable format is a b c d netmask where a b c dis the network and netmask is the netmask for example 192 168 100 8 255 255 255 0 Netgroups In the format group name where group name is the NIS netgroup name 3 3 Starting and Stopping the Server On the server that is exporting NFS file systems the nfs service must be running View the status of the NFS daemon with the following command sbin service nfs status Start the NFS daemon with the following command sb
266. ho Ethernet Active E ethO eth office Ethernet C active eth0 ethoO_home Ethernet Figure 17 16 Office Profile Notice that the Home profile as shown in Figure 17 17 Home Profile activates the ethO_home logical device which is associated with etho 183 Chapter 17 Network Configuration File Profile Help New Edit Copy Delete i Activate Deactivate Devices You may configure network devices associated with e 15 physical hardware here Multiple logical devices can be po associated with a single piece of hardware C active Getho etho Ethernet C active g eth0 etho_office Ethernet Active Er ethO ethO_home Ethernet Figure 17 17 Home Profile You can also configure etho to activate in the Office profile only and to activate a PPP modem device in the Home profile only Another example is to have the Common profile activate etho and an Away profile activate a PPP device for use while traveling To activate a profile at boot time modify the boot loader configuration file to include the netprofile lt profilename gt option For example if the system uses GRUB as the boot loader and boot grub grub conf contains title Red Hat Enterprise Linux 2 6 9 5 EL root hd0 0 kernel vmlinuz 2 6 9 5 EL ro root dev VolGroup00 LogVol00 rhgb quiet initrd fULMVELERH2 6o 9 5 o Wilh AMG Modify it to the following where lt profilename gt is the name of the profile to be activated at
267. hods are not enabled by default To enable one or more of these methods click the appropriate tab click the checkbox next to Enable and enter the appropriate information for the authentication method Refer to Chapter 26 Authentication Configuration for more information about the options 7 Firewall Configuration The Firewall Configuration window is similar to the screen in the installation program and the Security Level Configuration Tool File Help Basic Configuration Firewall Configuration Installation Method Security level Enable firewall Boot Loader Options ie Trusted devices Partition Information Network Configuration Authentication Firewall Configuration Trusted services C WWW HTTP Display Configuration C FTP Package Selection 7 Pre Installation Script SSH Post Installation Script O Telnet CI Mail SMTP Other ports 1029 tcp Figure 2 10 Firewall Configuration If Disable firewall is selected the system allows complete access to any active services and ports No connections to the system are refused or denied Selecting Enable firewall configures the system to reject incoming connections that are not in 47 Chapter 2 Kickstart Configurator response to outbound requests such as DNS replies or DHCP requests If access to services running on this machine is required you can choose to allow specific services through the firewall Only devices configured in t
268. hours 44 mins 32 interrupts second total 176226 Start profiter Flush profiler data Stop profiler Figure 40 2 OProfile Configuration If the Verbose option is selected the oprofiled daemon log includes more information 402 Additional Resources If Per application kernel samples files is selected OProfile generates per application profiles for the kernel and kernel modules as discussed in Section 2 3 Separating Kernel and User space Profiles This is equivalent to the opcontrol separate kernel command If Per application shared libs samples files is selected OProfile generates per application profiles for libraries This is equivalent to the opcontrol separate library command To force data to be written to samples files as discussed in Section 5 Analyzing the Data click the Flush profiler data button This is equivalent to the opcont rol dump command To start OProfile from the graphical interface click Start profiler To stop the profiler click Stop profiler Exiting the application does not stop OProfile from sampling 9 Additional Resources This chapter only highlights OProfile and how to configure and use it To learn more refer to the following resources 9 1 Installed Docs e usr share doc oprofile lt version gt oprofile html OProfile Manual e oprofile Man page Discusses opcontrol opreport opannotate and op_help 9 2 Useful Websites http oprof
269. how many inodes the user is currently using The last two columns are used to set the soft and hard inode limits for the user on the file system A hard limit is the absolute maximum amount of disk space that a user or group can use Once this limit is reached no further disk space can be used The soft limit defines the maximum amount of disk space that can be used However unlike the hard limit the soft limit can be exceeded for a certain amount of time That time is known as the grace period The grace period can be expressed in seconds minutes hours days weeks or months If any of the values are set to 0 that limit is not set In the text editor change the desired limits For example Disk quotas for user testuser uid 501 Filesystem blocks soft hard inodes soft hard dev VolGroup00 LogVol02 440436 500000 550000 37418 0 0 To verify that the quota for the user has been set use the command quota Lestuser 1 5 Assigning Quotas per Group Quotas can also be assigned on a per group basis For example to set a group quota for the devel group the group must exist prior to setting the group quota use the command edquota g devel This command displays the existing quota for the group in the text editor Disk quotas for group devel gid 505 Filesystem blocks soft hard inodes soft hard dev VolGroup00 LogVol02 440400 0 0 37418 0 0 Modify the limits save the file and then configure the quota To verify that
270. ice already exists for the Ethernet card the one just created is the alias such as eth0 1 Warning If you are configuring an Ethernet device to have an alias neither the device nor the alias can be configured to use DHCP You must configure the IP addresses manually Figure 17 18 Network Device Alias Example shows an example of one alias for the et ho device Notice the etho 1 device the first alias for ethno The second alias for etho would have the device name eth0 2 and so on To modify the settings for the device alias such as whether to activate it at boot time and the alias number select it from the list and click the Edit button 185 Chapter 17 Network Configuration File Profile Help 19 F B TE i x New Edit Copy Delete s Activate Deactivate You may configure network devices associated with 15 physical hardware here Multiple logical devices can be a associated with a single piece of hardware Proti ste pevce Netrame ive a ee Active Er ethO ethd 1 Ethernet z S Active etho etho Ethernet Figure 17 18 Network Device Alias Example Select the alias and click the Activate button to activate the alias If you have configured multiple profiles select which profiles in which to include it To verify that the alias has been activated use the command sbin ifconfig The output should show the device and the device alias with different IP addresses ethO Link encap Ethernet
271. ice is added it is configured not to start at boot time by default Edit its configuration to modify this setting Compression PPP options login name password and more can also be changed When the device is added it is not activated immediately as seen by its Inactive status To activate the device select it from the device list and click the Activate button If the system is configured to activate the device when the computer starts the default this step does not have to be performed again 5 Establishing an xDSL Connection DSL stands for Digital Subscriber Lines There are different types of DSL such as ADSL IDSL and SDSL The Network Administration Tool uses the term xDSL to mean all types of DSL connections Some DSL providers require that the system is configured to obtain an IP address through DHCP with an Ethernet card Some DSL providers require you to configure a PPPoE Point to Point Protocol over Ethernet connection with an Ethernet card Ask your DSL provider which method to use If you are required to use DHCP refer to Section 2 Establishing an Ethernet Connection to configure your Ethernet card If you are required to use PPPoE follow these steps 1 Click the Devices tab 2 Click the New button 3 Select xDSL connection from the Device Type list and click Forward 4 If your Ethernet card is in the hardware list select the Ethernet Device from the pulldown menu from the page shown in Figure 17
272. ich the user is a member The groups must exist prior to being specified here m Create the home directory if it does not exist M Do not create the home directory n Do not create a user private group for the user r Create a system account with a UID less than 500 and without a home directory p lt password gt The password encrypted with crypt s User s login shell which defaults to bin bash u lt uid gt User ID for the user which must be unique and greater than 499 Table 32 1 userada Command Line Options 2 3 Adding a Group To add a group to the system use the command groupada groupadd lt group name gt Command line options for groupadd are detailed in Table 32 2 groupada Command Line Options 325 Chapter 32 Users and Groups Option Description g lt gid gt Group ID for the group which must be unique and greater than 499 r Create a system group with a GID less than 500 f When used with g lt gid gt and lt gid gt already exists groupada will choose another unique lt gid gt for the group Table 32 2 groupadd Command Line Options 2 4 Password Aging For security reasons it is advisable to require users to change their passwords periodically This can be done when adding or editing a user on the Password Info tab of the User Manager To configure password expiration for a user from a shell prompt use the chage command follow
273. ict this privilege to certain users by taking the following steps 1 Add the a option to the etc inittab line shown above so that it reads Gaenictrlolkedelsy sbumn shutcowne a E3 i mow The a flag tells shutdown to look for the etc shutdown allow file 2 Create a file named shutdown allow in etc The shutdown allow file should list the usernames of any users who are allowed to shutdown the system using Ctrl Alt Del The format of the shutdown allow file is a list of usernames one per line like the following 299 Chapter 27 Console Access stephen jack sophie According to this example shutdown allow file the users stephen jack and sophie are allowed to shutdown the system from the console using Ctrl Alt Del When that key combination is used the shutdown a command in etc inittab checks to see if any of the users in etc shutdown allow or root are logged in on a virtual console If one of them is the shutdown of the system continues if not an error message is written to the system console instead For more information on shutdown allow refer to the shutdown man page 2 Disabling Console Program Access To disable access by users to console programs run the following command as root rm f etc security console apps In environments where the console is otherwise secured BIOS and boot loader passwords are set Ctrl Alt Delete is disabled the power and reset switches are disabled and so forth you
274. ief summary of the various options 9 2 Useful Websites http www nettilter org The official homepage of the Netfilter and iptables project http www tldp org The Linux Documentation Project contains several useful guides relating to firewall creation and administration http www iana org assignments port numbers The official list of registered and common service ports as assigned by the Internet Assigned Numbers Authority 9 3 Related Documentation e Red Hat Linux Firewalls by Bill McCarty Red Hat Press a comprehensive reference to building network and server firewalls using open source packet filtering technology such as Netfilter and iptables It includes topics that cover analyzing firewall logs developing firewall rules and customizing your firewall using various graphical tools Linux Firewalls by Robert Ziegler New Riders Press contains a wealth of information on building firewalls using both 2 2 kernel ipchains as well as Netfilter and iptables Additional security topics such as remote access issues and intrusion detection systems are also covered 204 Chapter 19 Controlling Access to Services Maintaining security on your system is extremely important and one approach for this task is to manage access to system services carefully Your system may need to provide open access to particular services for example httpd if you are running a Web server However if you do not need to
275. ig can also be used to configure a service to be started or not in a specific runlevel For example to turn nsca off in runlevels 3 4 and 5 use the following command chkconfig level 345 nscd off Warning Services managed by xinetd are immediately affected by chkconfig For example if xinetdis running finger is disabled and the command chkconfig finger on s executed finger is immediately enabled without having to restart xinetd manually Changes for other services do not take effect immediately after using chkconfig You must stop or start the individual service with the command service daemon stop In the previous example replace daemon with the name of the service you want to stop for example httpd Replace stop with start or restart to Start or restart the service 6 Additional Resources For more information refer to the following resources 6 1 Installed Documentation e The man pages for ntsysv chkconfig xinetd and xinetd conf man 5 hosts_access The man page for the format of host access control files in section 5 of the man pages 6 2 Useful Websites e http www xinetd org The xinetd webpage It contains a more detailed list of features and sample configuration files 6 3 Related Books Red Hat Enterprise Linux Reference Guide Red Hat Inc This companion manual contains detailed information about how TCP wrappers and xinetd allow or deny access as 211 Chapter 19 Con
276. iguration page Networking is only required if you choose a networking based installation method NFS FTP or HTTP Networking can always be configured after installation with the Network Administration Tool system config network Refer to Chapter 17 Network Configuration for details For each Ethernet card on the system click Add Network Device and select the network device and network type for the device Select ethO to configure the first Ethernet card eth1 for the second Ethernet card and so on 6 Authentication 45 Chapter 2 Kickstart Configurator File Help Basic Configuration Authentication Configuration Installation Method Authentication Use Shadow Passwords Use MDS Boot Loader Options Partition Information NisSthuibenticannn Network Configuration C Enable NIS Authentication Firewall Configuration NIS Domain Display Configuration C Use broadcast to find NIS server Package Selection SOG NIS Server Pre Installation Script Post Installation Script Figure 2 9 Authentication In the Authentication section select whether to use shadow passwords and MD5 encryption for user passwords These options are highly recommended and chosen by default The Authentication Configuration options allow you to configure the following methods of authentication e NIS e LDAP e Kerberos 5 e Hesiod e SMB 46 Firewall Configuration Name Switch Cache These met
277. iin 319 1 User and Group Configuration ccccceceeeeeeeee cece ee eeeeeeeeeeeeaeaaeaeeeeeeees 319 1 1 Adding a New User 00 0 ee erasana cece ne eeee cea KAATAEN RAEE RARAN 320 1 2 Modifying User Properties 2 0 0 ceeeccceeeeeeeaneeeeeeaaeeeeeeaaeeeeeeaaeeees 321 1 3 Adding a New Group cceceeeee eee eeeeeeeeeeeeeeaeaaeeeeeeeeeeeeaeaaeaaes 322 1 4 Modifying Group Properties ccceceeeeeeeeeeeaeeeeeteeeeeeeeeaeaaeenes 323 2 User and Group Management Tools eeceeeeeeeeeaeeeeeeeeeeeeeeaeaaeeees 324 2 1 Command Line Configuration cccccceeeeeeeeeeeeeeeaeeeeeeeeeeeeeeaes 324 2 2 AQGING a USET asno n EAA 324 2 0 Adding a Group saisit nerian aaa ia a Sa a EEE AA EEES 325 2 4 Password Aging esessssssissssirssssrriissrrirnsnriinsnnttannnnnannnnnannnnnnnn 326 2 5 Explaining the Process cceeeeeeeeeeeeeeeeeeeeeeeeeaeaaeeeeeeeeeeeeaea 328 By Standard WSSMs inaniinnd anemia aa aa a A Ea 330 4 Standard Gro pS s2 c ities inetd aa iaaa 332 5 User Private Groups iison atanarak aaan aeiaai 333 5 1 Group DIF6ClONGS sssuccccsswudessnns ezedetentivesessececeesnadedtnansdodceeatesaate 334 6 Shadow Passwords cceceeeeeeeeeeeeeeeeeeeeeeaeaaeeeeeeeeeeeeaeaaeaneneeseeeeeeaaa 335 7 Additional RESOUICES 0 eee eeeeeeeeeeeeeeeee eee ee eeeeeeeeeeeeaeeeeeeeaeeeesaaeeeeeeanaes 335 xi Red Hat Enterprise Linux 4 5 0 7 1 Installed Documentati
278. ilable Addresses frame shows the same window as the Add button except with the fields populated for the selected entry To delete an entry select it and click the Delete button Tip If you set the server to listen to a port under 1024 you must be root to start it For port 1024 and above httpd can be started as a regular user 257 Chapter 24 Apache HTTP Serve Listen to all addresses Address 192 168 1 4 Port Figure 24 2 Available Addresses 2 Default Settings After defining the Server Name Webmaster email address and Available Addresses click the Virtual Hosts tab and click the Edit Default Settings button A window as shown in Figure 24 3 Site Configuration appears Configure the default settings for your Web server in this window If you add a virtual host the settings you configure for the virtual host take precedence for that virtual host For a directive not defined within the virtual host settings the default value is used 2 1 Site Configuration The default values for the Directory Page Search List and Error Pages work for most servers If you are unsure of these settings do not modify them 258 Site Configuration Logging Environment Performance Directory Page Search List List of files to search for when a directory is requested Eg index html index shtml etc Error Pages Bad Request default Authorization Required default Forbidden def
279. ile sourceforge net Contains the latest documentation mailing lists IRC channels and more 403 404 Index Symbols dev oprofile 398 dev shm 384 etc auto master 222 etc exports 226 etc fstab 77 221 etc fstab file enabling disk quotas with 125 etc hosts 180 etc httpd conf httpd conf 255 etc sysconfig dhcpd 250 proc directory 386 var spool cron 351 A Access Control Lists see ACLs ACLs access ACLs 134 additional resources 137 archiving with 136 default ACLs 135 getfacl 135 mounting file systems with 133 mounting NFS shares with 133 on ext file systems 133 retrieving 135 setfacl 134 setting access ACLs 134 with Samba 133 adding group 325 user 324 Apache HTTP Server see HTTP Configuration Tool additional resources 274 related books 274 securing 278 APXS 276 at 351 additional resources 354 authconfig see Authentication Configuration Tool authentication 289 Authentication Configuration Tool 289 authentication 291 Kerberos support 291 LDAP support 292 MD5 passwords 292 shadow passwords 292 SMB support 292 Winbind 292 command line version 292 user information 289 cache 291 Hesiod 290 LDAP 290 NIS 290 Winbind 290 autofs 222 etc auto master 222 Automated Tasks 349 batch 351 additional resources 354 boot media 363 boot partition 85 booting emergency mode 71 rescue mode 68 single user mode 71 C
280. ile system with ACLs enabled for it and the kernel on the client system contains support for reading ACLs from ext3 file systems the client automatically recognizes and uses the ACLs Refer to Chapter 14 Access Control Lists for more information on ACLs 1 Why Use Samba Samba is useful if you have a network of both Windows and Linux machines Samba allows files and printers to be shared by all the systems in a network To share files between Linux machines only use NFS as discussed in Chapter 21 Network File System NFS To share printers between Linux machines only you do not need to use Samba refer to Chapter 33 Printer Configuration 2 Configuring a Samba Server The default configuration file etc samba smb conf allows users to view their home directories as a Samba share It also shares all printers configured for the system as Samba shared printers In other words you can attach a printer to the system and print to it from the Windows machines on your network 2 1 Graphical Configuration To configure Samba using a graphical interface use the Samba Server Configuration Tool For command line configuration skip to Section 2 2 Command Line Configuration The Samba Server Configuration Tool is a graphical interface for managing Samba shares users and basic server settings It modifies the configuration files in the etc samba directory Any changes to these files not made using the application are preserved To
281. ime e pD device e u user e G group mM mode includes permissions and file type e unreadable file If you see any output use your best judgment to determine if you should remove or reinstall the package or fix the problem in another way 3 Checking a Package s Signature If you wish to verify that a package has not been corrupted or tampered with examine only the md5sum by typing the following command at a shell prompt lt rpm file gt with file name of the RPM package 149 Chapter 15 Package Managemen rpm K nosignature lt rpm file gt The message lt rpm file gt md5 OK is displayed This brief message means that the file was not corrupted by the download To see a more verbose message replace x with Kvv in the command On the other hand how trustworthy is the developer who created the package If the package is signed with the developer s GnuPG key you know that the developer really is who they say they are An RPM package can be signed using Gnu Privacy Guard or GnuPG to help you make certain your downloaded package is trustworthy GnuPG is a tool for secure communication it is a complete and free replacement for the encryption technology of PGP an electronic privacy program With GnuPG you can authenticate the validity of documents and encrypt decrypt data to and from other recipients GnuPG is capable of decrypting and verifying PGP 5 x files as well During insta
282. ime and Date Properties Tool allows the user to change the system date and time to configure the time zone used by the system and to setup the Network Time Protocol NTP daemon to synchronize the system clock with a time server You must be running the X Window System and have root privileges to use the tool There are three ways to start the application e From the desktop go to Applications the main menu on the panel gt System Settings gt Date amp Time From the desktop right click on the time in the toolbar and select Adjust Date and Time e Type the command system config date system config time Of dateconfig at a Shell prompt for example in an XTerm or a GNOME terminal 1 Time and Date Properties As shown in Figure 28 1 Time and Date Properties the first tabbed window that appears is for configuring the system date and time 305 Chapter 28 Date and Time Con Date amp Time Network Time Protocol Date Time lt January 2005 gt Current Time 12 08 10 Sun Mon Tue Wed Thu Fri Sat igure 12 1 3 4 5 6 8 10 11 12 13 15 Second 44 17 18 BRM 20 22 24 25 26 27 29 31 Minute 7 Pax Figure 28 1 Time and Date Properties To change the date use the arrows to the left and right of the month to change the month use the arrows to the left and right of the year to change the year and click on the day of the week to change the day of the week To change the time
283. in seavace mis Start 228 Additional Resources Stop the NFS daemon with the following command sbin service nfs stop To start the nfs service at boot time use the command sbin chkconfig level 345 nfs on You can also use chkconfig ntsysv or the Services Configuration Tool to configure which services start at boot time Refer to Chapter 19 Controlling Access to Services for details 4 Additional Resources This chapter discusses the basics of using NFS For more detailed information refer to the following resources 4 1 Installed Documentation e The man pages for nfsd mountd exports auto master and autofs in manual sections 5 and 8 These man pages show the correct syntax for the NFS and autofs configuration files 4 2 Useful Websites htto nfs sourceforge net the NFS webpage includes links to the mailing lists and FAQs http www tidp org HOWTO NFS HOWT O index htm l The Linux NFS HOWTO from the Linux Documentation Project 4 3 Related Books e Managing NFS and NIS Services by Hal Stern O Reilly amp Associates Inc 229 230 Chapter 22 Samba Samba uses the SMB protocol to share files and printers across a network connection Operating systems that support this protocol include Microsoft Windows OS 2 and Linux The Red Hat Enterprise Linux 5 0 0 kernel contains Access Control List ACL support for ext3 file systems If the Samba server shares an ext3 f
284. ing 194 setting custom ports 194 trusted services 193 sendmail 375 services controlling access to 205 Services Configuration Tool 207 setfacl 134 Setup Agent via Kickstart 11 sftp see OpenSSH shadow passwords 292 overview of 335 shutdown disablingCtrlAltDel 299 single user mode 71 SMB 231 292 smb conf 231 smbclient 241 smbstatus 239 Software RAID see RAID ssh see OpenSSH ssh add 219 ssh agent 219 with GNOME 218 star 136 striping RAID fundamentals 95 swap space 109 creating 109 expanding 109 explanation of 109 file creating 111 113 LVM2 creating 110 extending 110 reducing 112 removing 113 moving 114 recommended size 109 removing 112 syslogd 355 system analysis OProfile see OProfile system information file systems 383 dev shm 384 gathering 379 hardware 384 memory usage 382 processes 379 currently running 379 system recovery 67 common problems 67 forgetting the root password 67 hardware software problems 67 reinstalling the boot loader 70 unable to boot into Red Hat Enterprise Linux 67 system config authentication see Authentication Configuration Tool system config date see Time and Date Properties Tool system config display see X Configuration Tool system config httpd see HTTP Configuration Tool system config keyboard 311 system config kickstart see Kickstart Configurator system config mouse see Mouse Configuration T
285. ing select to edit the device modify the Activate device when computer starts value and save the changes When the device is added it is not activated immediately as seen by its Inactive status To activate the device select it from the device list and click the Activate button If the system is configured to activate the device when the computer starts the default this step does not have to be performed again If you associate more than one device with an Ethernet card the subsequent devices are device aliases A device alias allows you to setup multiple virtual devices for one physical 165 Chapter 17 Network Configuration device thus giving the one physical device more than one IP address For example you can configure an eth1 device and an eth1 1 device For details refer to Section 11 Device Aliases 3 Establishing an ISDN Connection An ISDN connection is an Internet connection established with a ISDN modem card through a special phone line installed by the phone company ISDN connections are popular in Europe To add an ISDN connection follow these steps 1 Click the Devices tab 2 Click the New button on the toolbar 3 Select ISDN connection from the Device Type list and click Forward 4 Select the ISDN adapter from the pulldown menu Then configure the resources and D channel protocol for the adapter Click Forward to continue Select ISDN Adapter ISDN Adapters ACER P10 Resource D Ch
286. ing opreport on a Single Executable a e 395 5 3 Using Opannotate sssssssssasnsssssaannasasaannnnanaaanannsaaanannsaaananssaaanannna 397 6 Understanding dev oprofile cieceeccecececceeeeeeeeeeeeeeeeeeeeeeeeeeeeeeaeeeeeeeanees 398 fo Example Usage surne annann cutee ke election 398 8 Graphical Intenace stvaveseciiniavsrieocditsiewens veel beeeeda thea ev aa 399 9 Additional RESOUICES sessen ee eeeeeeeeeeee nese eee R RRA 403 9 1 Installed DOCS a fice saseven sisaivess Bete ent ought coder exci eK REEE 403 9 2 Useful WebSites sor arnan a S 403 DAEX irre E E E E E E 405 xiii xiv Introduction Welcome to the Red Hat Enterprise Linux System Administration Guide The Red Hat Enterprise Linux System Administration Guide contains information on how to customize your Red Hat Enterprise Linux system to fit your needs If you are looking for a step by step task oriented guide for configuring and customizing your system this is the manual for you This manual discusses many intermediate topics such as the following e Setting up a network interface card NIC e Performing a Kickstart installation Configuring Samba shares e Managing your software with RPM e Determining information about your system Upgrading your kernel This manual is divided into the following main categories Installation Related Reference e File Systems Reference e Package Management e Network Configuration e System Configuration e
287. ion on Apache HTTP Server version 2 0 including the Apache HTTP Server Version 2 0 User s Guide http www redhat com support resources web_ftp apache htm Red Hat Support maintains a list of useful Apache HTTP Server links http www redhat com support docs faqs RH apache FAQ book1 htm l The Apache Centralized Knowledgebase compiled by Red Hat 7 3 Related Books Apache The Definitive Guide by Ben Laurie and Peter Laurie O Reilly amp Associates Inc Red Hat Enterprise Linux Reference Guide Red Hat Inc This companion manual includes instructions for migrating from Apache HTTP Server version 1 3 to Apache HTTP Server version 2 0 manually more details about the Apache HTTP Server directives and instructions for adding modules to the Apache HTTP Server 274 Chapter 25 Apache HTTP Secure Server Configuration 1 Introduction This chapter provides basic information on the Apache HTTP Server with the mod_ss1 security module enabled to use the OpenSSL library and toolkit The combination of these three components are referred to in this chapter as the secure Web server or just as the secure server The mod_ss1 module is a security module for the Apache HTTP Server The mod_ss1 module uses the tools provided by the OpenSSL Project to add a very important feature to the Apache HTTP Server the ability to encrypt communications In contrast regular HTTP communications between a browser and a Web server
288. isk crashes The underlying concept of RAID is that data may be distributed across each drive in the array in a consistent manner To do this the data must first be broken into consistently sized chunks often 32K or 64K in size although different sizes can be used Each chunk is then written to a hard drive in the RAID array according to the RAID level used When the data is to be read the process is reversed giving the illusion that the multiple drives in the array are actually one large drive 2 Who Should Use RAID Those who need to keep large quantities of data on hand such as system administrators would benefit by using RAID technology Primary reasons to use RAID include Enhanced speed e Increased storage capacity using a single virtual disk e Lessened impact of a disk failure 3 Hardware RAID versus Software RAID There are two possible RAID approaches Hardware RAID and Software RAID 3 1 Hardware RAID The hardware based array manages the RAID subsystem independently from the host and presents to the host only a single disk per RAID array An example of a Hardware RAID device would be one that connects to a SCSI controller and presents the RAID arrays as a single SCSI drive An external RAID system moves all RAID handling intelligence into a controller located in the external disk subsystem The whole 95 Chapter 9 Redundant Array of subsystem is connected to the host via a normal SCSI controller
289. ister it with Red Hat Network to receive Errata Updates The registration process gathers information about the system that is required to notify you of updates For example a list of packages installed on the system is compiled so you are only notified about updates that are relevant to your system The first time the system is booted the Software Update Setup Assistant prompts you to register If you did not register then select Applications the main menu on the panel gt System Tools gt Package Updater on your desktop to start the registration process Alternately execute the command yum update from a shell prompt Step 3 Register a System Profile Packages ws RPM information is important to determine what updated software packages are relevant to this system Include RPM packages installed on this system in my System Profile Below is a list of packages present on your system that RPM knows about a Package Name Version Release 4Suite 0 11 1 14 GConf 1 0 9 12 GConf2 2 2 1 1 Glide3 2001052 25 MAKEDEV 3 3 6 1 ORBit 0 5 17 10 4 ORBit2 2 6 2 1 By default all packages that RPM knows about will be included in your System Profile Uncheck any packages which you do not want to be included Figure 16 3 Registering with RHN After registering use one of the following methods to start receiving updates 157 Chapter 16 Red Hat Network Select Applications the main menu on the panel gt S
290. ity alerts By default Red Hat Network installs the packages as well You do not have to learn how to use RPM or worry about resolving software package dependencies RHN does it all Red Hat Network features include e Errata Alerts learn when Security Alerts Bug Fix Alerts and Enhancement Alerts are issued for all the systems in your network 155 Chapter 16 Red Hat Network File Edit View Go Bookmarks Tools Help Q J Red Hat Network Errata Relevant 6 QM Ce reo HAT NETWORK Locceo im andriusb SIGN ouT Your RHN Systems Erata Channels Schedule Users Help Systems A t S Q Search NO SYSTEMS SELECTED Manage Clear as eg Errata Relevant to Your Systems All 1 20 of 219 gt gt I RHSA 2005 059 Updated Xpdf package fixes security issue 2 2005 01 26 Eran tegen a RHSA 2005 068 Updated less package fixes security issue 2 2005 01 26 8 a RHSA 2005 012 Updated krb5 packages fix security vulnerabilities 2 2005 01 19 bd e RHSA 2005 043 Updated kernel packages fix security vulnerabilities 2 2005 01 18 F Daa RHSA 2004 635 Updated ruby package fixes denial of service issue 2 2005 01 17 BUY NOW RHSA 2005 019 Updated libtiff packages fix security issues 2 2005 01 13 paperan RHSA 2005 038 Updated mozilla packages fix a buffer overflow 2 2005 01 13 pooo ali RHSA 2005 018 Updated Xpdf packages fix security issues 2 2005 01 12 m RHSA 2005 013 Updated CUPS packag
291. k Forward to continue 6 In the Configure Network Settings window shown in Figure 17 2 Ethernet Settings choose between DHCP and a static IP address If the device receives a different IP address each time the network is started do not specify a hostname Click Forward to continue 7 Click Apply on the Create Ethernet Device page 163 Chapter 17 Network Configuration Configure Network Settings Automatically obtain IP address settings with DHCP Settings VS Automatically obtain DNS information from provider Statically set IP addresses Manual IP Address Settings Figure 17 2 Ethernet Settings After configuring the Ethernet device it appears in the device list as shown in Figure 17 3 Ethernet Device 164 Establishing an Ethernet Connection File Profile Help Ss ff B y New Edit Copy Delete Activate Deactivate Devices Hardare Pec ONS Hosts aLO You may configure network devices associated with 45 physical hardware here Multiple logical devices can be p associated with a single piece of hardware r A Inactive p ethO eth Ethernet Figure 17 3 Ethernet Device Be sure to select File gt Save to save the changes After adding the Ethernet device you can edit its configuration by selecting the device from the device list and clicking Edit For example when the device is added it is configured to start at boot time by default To change this sett
292. kernel module if it is not already loaded and creates the dev oprofile directory if it does not already exist Refer to Section 6 Understanding dev oprofile for details about this directory Note Even if OProfile is configured not to profile the kernel the SMP kernel still must be running so that the oprofile module can be loaded from it Setting whether samples should be collected within the kernel only changes what data is collected not how or where the collected data is stored To generate different sample files for the kernel and application libraries refer to Section 2 3 Separating Kernel and User space Profiles 2 2 Setting Events to Monitor Most processors contain counters which are used by OProfile to monitor specific events As shown in Table 40 2 OProfile Processors and Counters the number of counters available depends on the processor Processor cpu_type Number of Counters Pentium Pro i386 ppro 2 Pentium II i386 pii 2 Pentium III i386 piii 2 Pentium 4 non hyper threaded i386 p4 8 Pentium 4 hyper threaded i386 p4 ht 4 Athlon i386 athlon 4 AMD64 x86 64 hammer 4 Itanium ia64 itanium 4 Itanium 2 ia64 itanium2 4 389 Chapter 40 OProfile Processor cpu_type Number of Counters TIMER_INT timer 1 IBM eServer iSeries and pSeries timer 1 ppc64 power4 8 ppc64 power5 6 ppc64 970 8 IBM eServer S 390 and S 390x timer 1 IBM eServ
293. l type the following command at a shell prompt ssh keygen t dsa Accept the default file location of ssh id_dsa Enter a passphrase different from your account password and confirm it by entering it again Tip A passphrase is a string of words and characters used to authenticate a user Passphrases differ from passwords in that you can use spaces or tabs in the passphrase Passphrases are generally longer than passwords because they are usually phrases instead of a single word The public key is written to ssh id_dsa pub The private key is written to ssh id_dsa It is important never to give anyone the private key 2 Change the permissions of the ssh directory with the following command 217 Chapter 20 OpenSSH chmod 755 ssh 3 Copy the contents of ssh id_dsa pub into the file ssh authorized_keys on the machine to which you want to connect If the file ssh authorized_keys exist append the contents of the file ssh id_dsa pub to the file ssh authorized_keys on the other machine 4 Change the permissions of the authorized_keys file using the following command chmod 644 ssh authorized_keys 5 If you are running GNOME skip to Section 3 4 4 Configuring ssh agent with GNOME If you are not running the X Window System skip to Section 3 4 5 Configuring ssh agent 3 4 3 Generating an RSA Key Pair for Version 1 3 and 1 5 Use the following steps to generate an RSA ke
294. l host add any additional virtual hosts 5 Configure the server settings under the Server tab 6 Configure the connections settings under the Performance Tuning tab 7 Copy all necessary files to the DocumentRoot and cgi bin directories 8 Exit the application and select to save your settings 1 Basic Settings Use the Main tab to configure the basic server settings Virtual Hosts Performance Tuning Basic Setup Server Name Webmaster email address root localhost Available Addresses All available addresses on port 80 Set addresses for Apache to listen for requests on ie Figure 24 1 Basic Settings Enter a fully qualified domain name that you have the right to use in the Server Name text area This option corresponds to the ServerName http httpd apache org docs 2 0 mod core html servername directive in httpd conf The ServerName directive sets the hostname of the Web server It is used when creating redirection 256 Basic Settings URLs If you do not define a server name the Web server attempts to resolve it from the IP address of the system The server name does not have to be the domain name resolved from the IP address of the server For example you might set the server name to www example com while the server s real DNS name is foo example com Enter the email address of the person who maintains the Web server in the Webmaster email address text area This option corresponds
295. les symbol name a 100 000 _ gconv_transform_utf8_internal The first line is a summary for the symbol executable combination The first column is the number of samples for the memory symbol The second column is the percentage of samples for the memory address relative to the total number of samples for the symbol The third column is the symbol name 396 Using opannotate d List sample data by symbols with more detail than 1 For example the following output is from the command opreport 1 d __gconv_transform_utf8_internal lib tls libc lt version gt so vma samples 4 symbol name 00a98640 12 100 000 _ gconv_transform_utf8_internal 00a98640 1 8 33353 00a9868c 2 16 6667 00a9869a 1 8 3353 00a986cl1 1 Bo 3333 00a98720 1 8 3353 00a98749 1 3 3333 00a98753 1 3 3333 00a98789 1 3 3333 00a98864 1 3 3333 00a98869 1 863353 00a98b08 1 Bo 3353 The data is the same as the 1 option except that for each symbol each virtual memory address used is shown For each virtual memory address the number of samples and percentage of samples relative to the number of samples for the symbol is displayed x lt symbol name gt Exclude the comma separated list of symbols from the output session lt name gt Specify the full path to the session or a directory relative to the var lib oprofile samples directory 5 3 Using opannotate The opannotate tool tries to match the samples for particular instructions to the corres
296. les and Connection Tracking ccccececeeeeeeeeeeeeeeeeaaeeeeeeeeeeeeeeaaa 202 Ba IP VG oiiaii anaa a a aaia a a Ea Aa aE A EEA a 203 9 Additional RESOUICOS wecccassseoressesuecdeebercdenakeedas AE ER aden 203 9 1 Installed Documentation cece cece eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeenees 203 9 2 Useful Websites 20 0 cece ee cece cence eee ee ener ence ee eeaaeeeeeeaaeeeeeneee 204 9 3 Related Documentation 0 ce eeeeeeee cece eeeeeeeeeeeeeeeeeeeeeeeeeaeeeeeeanees 204 19 Controlling Access to Services 0 ccececeeeeeeeee cece eee eeeteeeeeeeeeaeaaeaneneeeeeeeeeaaa 205 Tee FAUMIGVGIS a E 206 22 TGP WAP DCIS seecivessicveeli geccessbaiv tds Ea A be odds a ce aeaes 206 2 lia RPMS x aasacdadaahavevaconagageuasdisnewasanadavanseanenawaeautioanaevannwanatgaasedionnd 207 3 Services Configuration Tool c cccceceeeeeeeeee ee eeeeeeeeeeeeeeaeaaeeees 207 d MISYSV noaaraa T O T velvaamoessaaupd cst team Girabawaced ees 210 5 CHK GONE TG airesin T vacnnaelsauebiegs aed AREE 210 6 Additional R6SOurceS 22 2222 d cescete seven lencebe tok EENE 211 6 1 Installed DocUMENtation sesiis neiii aina 211 6 2 Usetul Websites icicceciccscticoeiet ceveeensbevenientheveestcieonsblaeeeenenevenanees 211 6 3 Related BOOKS ceeeeececeeeee ee eeeeee ee ee eee nese ceee ee eeeaeeeeeeaaeeeenees 211 20 OPENS SEI eter tee ecrerrererrt eee E T E reer T ere Terre 213 1 Why Use OpenSSH 000 2 ceccceceeeee
297. linux file so that the settings can be restored the next time the application is started Do not edit this file by hand Even though the firewall is activated immediately the iptables service is not configured to start automatically at boot time Refer to Section 2 6 Activating the IPTables Service for more information 2 6 Activating the IPTables Service The firewall rules are only active if the iptables service is running To manually start the service use the following command root myServer service iptables restart 194 Using IPTables To ensure that iptables starts when the system is booted use the following command root myServer chkconfig level 345 iptables on The ipchains service is not included in Red Hat Enterprise Linux However if ipchains is installed for example an upgrade was performed and the system had ipchains previously installed the ipchains and iptables services should not be activated simultaneously To make sure the ipchains service is disabled and configured not to start at boot time use the following two commands root myServer service ipchains stop root myServer chkconfig level 345 ipchains off 3 Using IPTables The first step in using iptables is to start the iptables service Use the following command to start the iptables service root myServer service iptables start Note The ip6 tables service can be turned off if you intend to use the ip
298. llation GnuPG is installed by default That way you can immediately start using GnuPG to verify any packages that you receive from Red Hat First you must import Red Hat s public key 3 1 Importing Keys To verify Red Hat packages you must import the Red Hat GPG key To do so execute the following command at a shell prompt rpm import usr share rhn RPM GPG KEY To display a list of all keys installed for RPM verification execute the command rpm qa gpg pubkey For the Red Hat key the output includes gpg pubkey db42a60e 37ea5438 To display details about a specific key use rpm qi followed by the output from the previous command rpm qi gpg pubkey db42a60e 37ea5438 3 2 Verifying Signature of Packages 150 Impressing Your Friends with RPM To check the GnuPG signature of an RPM file after importing the builder s GnuPG key use the following command replace lt rpm Ffile gt with filename of the RPM package rpm K lt rpm file gt If all goes well the following message is displayed md5 gpg ox That means that the signature of the package has been verified and that it is not corrupt 4 Impressing Your Friends with RPM RPM is a useful tool for both managing your system and diagnosing and fixing problems The best way to make sense of all of its options is to look at some examples e Perhaps you have deleted some files by accident but you are not sure what you deleted To verify your entire s
299. llowable Drives C sdb 8676 MB IBM PSG ST39204LC Size MB 100 Additional Size Options Fixed size Fill all space up to MB Fill to maximum allowable size Ja Figure 10 3 Adding a RAID Partition 4 Enter the size that you want the partition to be 5 Select Fixed size to make the partition the specified size select Fill all space up to MB and enter a size in MBs to give range for the partition size or select Fill to maximum allowable size to make it grow to fill all available space on the hard disk If you make more than one partition growable they share the available free space on the disk 6 Select Force to be a primary partition if you want the partition to be a primary partition A primary partition is one of the first four partitions on the hard drive If unselected the partition is created as a logical partition If other operating systems are already on the system unselecting this option should be considered For more information on primary versus logical extended partitions refer to the appendix section of the Red Hat Enterprise Linux Installation Guide 7 Click OK to return to the main screen Repeat these steps to create as many partitions as needed for your RAID setup Notice that all the partitions do not have to be RAID partitions For example you can configure only the boot partition as a software RAID device leaving the root partition home and swap as 102 Creating the R
300. llowing example shows a rule that uses connection tracking to forward only the packets that are associated with an established connection root myServer iptables A FORWARD m stat stat ESTABLISHED RELATED J ACCEPT 8 IPv6 The introduction of the next generation Internet Protocol called IPv6 expands beyond the 32 bit address limit of IPv4 or IP IPv6 supports 128 bit addresses and carrier networks that are IPv6 aware are therefore able to address a larger number of routable addresses than Pv4 Red Hat Enterprise Linux supports IPv6 firewall rules using the Netfilter 6 subsystem and the ip6tables command In Red Hat Enterprise Linux 5 both IPv4 and IPv6 services are enabled by default The ip6tables command syntax is identical to iptables in every aspect except that it supports 128 bit addresses For example use the following command to enable SSH connections on an IPv6 aware network server root myServer ip6tables A INPUT i eth0 p tcp s SETS SIOOZ sil ilZ23 dport 22 ACCEL For more information about IPv6 networking refer to the IPv6 Information Page at http www ipv6 org 9 Additional Resources There are several aspects to firewalls and the Linux Netfilter subsystem that could not be covered in this chapter For more information refer to the following resources 9 1 Installed Documentation 203 Chapter 18 Firewalls e The iptables man page contains a br
301. log rpmpkgs Refresh Rate Refresh log file every seconds Figure 35 2 Log File Locations 3 Adding a Log File To add a log file to the list select Edit gt Preferences and click the Add button in the Log Files tab 357 Chapter 35 Log Files Xe Specify a new log file location Name Custom Log Description a description of my custom log Location var log custom log Figure 35 3 Adding a Log File Provide a name description and the location of the log file to add After clicking OK the file is immediately added to the viewing area if the file exists 4 Examining Log Files Log Viewer can be configured to display an alert icon beside lines that contain key alert words and a warning icon beside lines that contain key warning words To add alerts words select Edit gt Preferences from the pulldown menu and click on the Alerts tab Click the Add button to add an alert word To delete an alert word select the word from the list and click Delete The alert icon EJ s displayed to the left of the lines that contains any of the alert words 358 Examining Log Files Tog les Show alert icon for the following key words fail denied rejected oops segfault segmentation x Close Figure 35 4 Alerts To add warning words select Edit gt Preferences from the pull down menu and click on the Warnings tab Click the Add button to add a warning word To delete
302. loping applications which include SSL support you do not need this package to use SSL stunnel The stunnel package provides the Stunnel SSL wrapper Stunnel supports the SSL encryption of TCP connections It provides encryption for non SSL aware daemons and protocols such as POP IMAP and LDAP without requiring any changes to the daemon s code Note Newer implementations of various daemons now provide their services natively over SSL such as dovecot or OpenLDAP s slapa server which may be more desirable than using stunnel For example use of stunnel only provides wrapping of protocols while the native support in OpenLDAP s slapa can also handle in band upgrades for using encryption in response to a start TLs client request Table 25 1 Security Packages displays a summary of the secure server packages and whether each package is optional for the installation of a secure server Package Name Optional httpd no mod_ssl no openssl no httpd devel yes openssh yes openssh askpass yes openssh askpass gnome yes openssh clients yes openssh server yes openssl devel yes stunnel yes Table 25 1 Security Packages 277 Chapter 25 Apache HTTP Secur 3 An Overview of Certificates and Security Your secure server provides security using a combination of the Secure Sockets Layer SSL protocol and in most cases a digital certificate from a Certificate Authority
303. lt mode gt must be one of the following 1 List sample data by symbols For example the following is part of the output from running the command opreport 1 lib tls libc lt version gt so 395 Chapter 40 OProfile si PRPPPPPPP PEPE a S S S a a a a WW Ww WwW samples symbol name ee 21 4286 _ gconv_transform_utf8_internal 9286 aime _iimell iho 1429 malloc S57 16086 Gr OE ENEN Epos 3571 _dli_mcount_wrapper_check sSHTiL wmloricowe 3571 memcpy sata _aline_iceall loc Zoa nl_intern_locale_data 5714 free 5714 strcmp a HSS 7 ctype_get_mb_cur_max 7857 __unregister_atfork 7857 _ write _nocancel aloa CU acker TOT ANE Eres o VOSI LEGEL WOTE 7857 calc_eclosure_iter 7857 fopen GLIBC_2 1 7857 getpid 7857 memmove 7857 msort_with_tmp 5 LIST Ertrag 7857 strlen HSS VEDEN ie 7857 write PREP RPP PP PEP PEP PEP PPP WWWWUHTo4a 8e bP The first column is the number of samples for the symbol the second column is the percentage of samples for this symbol relative to the overall samples for the executable and the third column is the symbol name To sort the output from the largest number of samples to the smallest reverse order use r in conjunction with the 1 option lt symbol name gt List sample data specific to a symbol name For example the following output is from the command opreport 1 i __gconv_transform_utf8_internal lib tls libc lt version gt so samp
304. man cupsd The manual page for the CUPS printer daemon man cupsd conf The manual page for the CUPS printer daemon configuration file man classes conf The manual page for the class configuration file for CUPS 9 2 Useful Websites http www linuxprinting org GNU Linux Printing contains a large amount of information about printing in Linux http www cups org Documentation FAQs and newsgroups about CUPS 347 348 Chapter 34 Automated Tasks In Linux tasks can be configured to run automatically within a specified period of time on a specified date or when the system load average is below a specified number Red Hat Enterprise Linux is pre configured to run important system tasks to keep the system updated For example the slocate database used by the locate command is updated daily A system administrator can use automated tasks to perform periodic backups monitor the system run custom scripts and more Red Hat Enterprise Linux comes with several automated tasks utilities cron at and batch 1 Cron Cron is a daemon that can be used to schedule the execution of recurring tasks according to a combination of the time day of the month month day of the week and week Cron assumes that the system is on continuously If the system is not on when a task is scheduled it is not executed To schedule one time tasks refer to Section 2 At and Batch To use the cron service the vixi
305. manl tload 1 gz usr share man manl top 1 gz usr share man manl uptime 1 gz usr share man manl w 1 gz usr share man manl watch 1 gz usr share man man5 sysctl conf 5 gz usr share man man8 sysctl 8 gz usr share man man8 vmstat 8 gz e You may find a new RPM but you do not know what it does To find information about it use the following command Ho Calis ecwomcalos il 10 7 mocicela wien The output would be similar to the following Name Cromiaos Relocations not relocatable Version leas Vendor Red Hat Inc Release al Build Date Mon 20 Sep 2004 OSs Ses 0 IM jaye Install Date not installed garle lose tweety build redhat com Group System Environment Base Source RPM crontabs LW 7 SCS Tre Size 1004 License Public Domain Signature DSA SHA1 Wed 05 Jan 2005 06 05 25 PM EST Key ID 219180cddb42a60e Packager Red Hat Inc lt http bugzilla redhat com bugzilla gt Summary Root crontab files used to schedule the execution of programs Description The crontabs package contains root crontab files Crontab is the 152 Additional Resources program used to install uninstall or list the tables used to drive the cron daemon The cron daemon checks the crontab files to see when particular commands are scheduled to b xecuted If commands are scheduled then it executes them e Perhaps you now want to see what files the crontabs RPM installs You would enter the following
306. matically detected and listed in the Share column Click the arrow beside a Workgroup to expand it From the expanded list select a printer If the printer you are looking for does not appear in the list enter the SMB address in the smb field Use the format computer name printer share In Figure 33 5 Adding a SMB Printer the computer name iS dellbox while the printer shareisS r2 In the Username field enter the username to access the printer This user must exist on the SMB system and the user must have permission to access the printer The default user name is typically guest for Windows servers or nobody for Samba servers Enter the Password if required for the user specified in the Username field You can then test the connection by clicking Verify Upon successful verification a dialog box appears confirming printer share accessibility Next select the printer type Refer to Section 5 Selecting the Printer Model and Finishing for details Warning d Samba printer usernames and passwords are stored in the printer server as unencrypted files readable by root and Ipd Thus other users that have root access to the printer server can view the username and password you use to o 341 Chapter 33 Printer Configuration access the Samba printer As such when you choose a username and password to access a Samba printer it is advisable that you choose a password that is different from what yo
307. might guess the BOOTP method is similar requiring a BOOTP server to supply the networking configuration To direct a system to use DHCP network bootproto dhcp To direct a machine to use BOOTP to obtain its networking configuration use the following line in the kickstart file network bootproto bootp The static method requires that you enter all the required networking information in the kickstart file As the name implies this information is static and are used during and after the installation The line for static networking is more complex as you must include all 15 Chapter 1 Kickstart Installa network configuration information on one line You must specify the IP address netmask gateway and nameserver For example the indicates that this should be read as one continuous line network bootproto static ip 10 0 2 15 netmask 255 255 255 0 gateway 10 0 2 254 nameserver 10 0 2 1 If you use the static method be aware of the following two restrictions e All static networking configuration information must be specified on one line you cannot wrap lines using a backslash for example e You can only specify one nameserver here However you can use the kickstart file s post section described in Section 7 Post installation Script to add more name servers if needed device Used to select a specific Ethernet device for installation Note that using device is
308. mises the regular UNIX security on the host machine that person could obtain your private key the contents of your server key file The key could be used to serve webpages that appear to be from your secure server If UNIX security practices are rigorously maintained on the host computer all operating system patches and updates are installed as soon as they are available no unnecessary or risky services are operating and so on secure server s passphrase may seem unnecessary However since your secure server should not need to be re booted very often the extra security provided by entering a passphrase is a worthwhile effort in most cases The server key file should be owned by the root user on your system and should not be accessible to any other user Make a backup copy of this file and keep the backup copy in a safe secure place You need the backup copy because if you ever lose the server key file after using it to create your certificate request your certificate no longer works and the CA is not able to help you Your only option is to request and pay for a new certificate If you are going to purchase a certificate from a CA continue to Section 7 Generating a Certificate Request to Send to a CA lf you are generating your own self signed certificate continue to Section 8 Creating a Self Signed Certificate 7 Generating a Certificate Request to Send to a CA Once you have created a key the next step is to gener
309. mmas firstboot optional Determine whether the Setup Agent starts the first time the system is booted If enabled the firstboot package must be installed If not specified this option is disabled by default enable The Setup Agent is started the first time the system boots disable The Setup Agent is not started the first time the system boots reconfig Enable the Setup Agent to start at boot time in reconfiguration mode This mode enables the language mouse keyboard root password security level time zone and networking configuration options in addition to the default ones halt optional Halt the system after the installation has successfully completed This is similar to a manual installation where anaconda displays a message and waits for the user to press a key before rebooting During a kickstart installation if no completion method is specified the reboot option is used as default The halt option is roughly equivalent to the shutdown h command For other completion methods refer to the poweroff reboot and shutdown kickstart options install optional Tells the system to install a fresh system rather than upgrade an existing system This is the 11 Chapter 1 Kickstart Installa default mode For installation you must specify the type of installation from cdrom harddrive nfs Or url for FTP or HTTP installations The insta11 command and the installation method command must
310. mount o nolock 10 10 0 2 usr new machines mnt temp open s w mnt temp runme umount mnt temp 28 Making the Kickstart File Available Note NFS file locking is not supported while in kickstart mode therefore o nolock is required when mounting an NFS mount Add a user to the system usr sbin useradd bob usr bin chfn f Bob Smith bob usr sbin usermod e kjdf 04930FTH bob 8 Making the Kickstart File Available A kickstart file must be placed in one of the following locations On aboot diskette On aboot CD ROM On a network Normally a kickstart file is copied to the boot diskette or made available on the network The network based approach is most commonly used as most kickstart installations tend to be performed on networked computers Let us take a more in depth look at where the kickstart file may be placed 8 1 Creating Kickstart Boot Media Diskette based booting is no longer supported in Red Hat Enterprise Linux Installations must use CD ROM or flash memory products for booting However the kickstart file may still reside on adiskette s top level directory and must be named ks cfg To perform a CD ROM based kickstart installation the kickstart file must be named ks cfg and must be located in the boot CD ROM s top level directory Since a CD ROM is read only the file must be added to the directory used to create the image that is written to the CD ROM Refer to the Red Hat Enterp
311. move any partitions cmdline optional Perform the installation in a completely non interactive command line mode Any prompts for interaction halts the install This mode is useful on S 390 systems with the x3270 console device optional On most PCI systems the installation program autoprobes for Ethernet and SCSI cards properly On older systems and some PCI systems however kickstart needs a hint to find the proper devices The device command which tells the installation program to install extra modules is in this format device lt type gt lt moduleName gt opts lt options gt lt type gt Replace with either scsi or eth lt moduleName gt Replace with the name of the kernel module which should be installed opts Chapter 1 Kickstart Installa Options to pass to the kernel module Note that multiple options may be passed if they are put in quotes For example opts aicl52x 0x340 io 11 driverdisk optional fi Driver diskettes can be used during kickstart installations You must copy the driver diskettes s contents to the root directory of a partition on the system s hard drive Then you must use the driverdisk command to tell the installation program where to look for the driver disk driverdisk lt partition gt type lt fstype gt Alternatively a network location can be specified for the driver diskette driverdisk source ftp path to dd imgdriverdisk source http
312. mpt type the following command smbclient lt hostname gt lt sharename gt U lt username gt 241 Chapter 22 Samba Replace lt hostname gt with the hostname or IP address of the Samba server you want to connect to lt sharename gt with the name of the shared directory you want to browse and lt username gt with the Samba username for the system Enter the correct password or press Enter if no password is required for the user If you see the smb gt prompt you have successfully logged in Once you are logged in type help for a list of commands If you wish to browse the contents of your home directory replace sharename with your username If the u switch is not used the username of the current user is passed to the Samba server To exit smbclient type exit at the smb gt prompt 3 2 Mounting the Share Sometimes it is useful to mount a Samba share to a directory so that the files in the directory can be treated as if they are part of the local file system To mount a Samba share to a directory create the directory if it does not already exist and execute the following command as root mount t smbfs o username lt username gt lt servername gt lt sharename gt mnt point This command mounts lt sharename gt from lt servername gt in the local directory mnt point 4 Additional Resources For configuration options not covered here please refer to the following resources 4 1 Inst
313. mt2 Cir Ozalit Gu usS ciexeu cle de latinl de latinl nodeadkeys dk dk latinl dvorak es et fi ti latimil te txr latind Er latimil fe pe i Chy ite Chi latimi gz Inu Wall as ilatiainil it ne llom 22 Jele le letimil me wieit MO MO latimil jel wt latinil roOwinm mu ru cplZ25l rusms rul LUZ ru_win se latinl sg sg latinl sk qwerty slovene speakup speakup lt sv latinl sg sg latinl sk querty slovene trq ua uk WSs UWs ecentos The file usr lib python2 2 site packages rhpl keyboard_models py also contains this list and is part of the rhp1 package lang required Sets the language to use during installation For example to set the language to English the kickstart file should contain the following line lang en_US The file usr share system config language locale list provides a list of the valid language codes in the first column of each line and is part of the system config language package langsupport required Sets the language s to install on the system The same language codes used with lang can be used with Langsupport To install one language specify it For example to install and use the French language fr_FR langsupport fr_FR 13 Chapter 1 Kickstart Installa default If language support for more than one language is specified a default must be identified For example to install English and French and use English as the default language l
314. n enlarged usable workspace Selecting Individual Desktops shares the mouse and keyboard among the displays but restricts windows to a single display 318 Chapter 32 Users and Groups The control of users and groups is a core element of Red Hat Enterprise Linux system administration Users can be either people meaning accounts tied to physical users or accounts which exist for specific applications to use Groups are logical expressions of organization tying users together for a common purpose Users within a group can read write or execute files owned by that group Each user and group has a unique numerical identification number called a userid UID and a groupid GID respectively A user who creates a file is also the owner and group owner of that file The file is assigned separate read write and execute permissions for the owner the group and everyone else The file owner can be changed only by the root user and access permissions can be changed by both the root user and file owner Red Hat Enterprise Linux also supports access control lists ACLs for files and directories which allow permissions for specific users outside of the owner to be set For more information about ACLs refer to Chapter 14 Access Control Lists 1 User and Group Configuration The User Manager allows you to view modify add and delete local users and groups To use the User Manager you must be running the X Window System hav
315. n use the resize command followed by the minor number for the partition the starting place in megabytes and the end place in megabytes For example resize 3 1024 204A After resizing the partition use the print command to confirm that the partition has been resized correctly is the correct partition type and is the correct file system type After rebooting the system into normal mode use the command af to make sure the partition was mounted and is recognized with the new size 2 LVM Partition Management The following commands can be found by issuing 1vm help at a command prompt Command Description dumpconfig Dump the active configuration formats List the available metadata formats help Display the help commands lvchange Change the attributes of logical volume s lvcreate Create a logical volume lvdisplay Display information about a logical volume lvextend Add space to a logical volume lvmchange Due to use of the device mapper this command has been deprecated 121 Chapter 12 Managing Disk Storage Command Description lvmdiskscan List devices that may be used as physical volumes lvmsadc Collect activity data lvmsar Create activity report lvreduce Reduce the size of a logical volume lvremove Remove logical volume s from the system lvrename Rename a logical volume lvre
316. n IP address it refers to the etc hosts file before using the name servers if you are using the default Red Hat Enterprise Linux configuration If the IP address is listed in the etc hosts file the name servers are not used If your network contains computers whose IP addresses are not listed in DNS it is recommended that you add them to the etc hosts file To add an entry to the etc hosts file go to the Hosts tab click the New button on the toolbar provide the requested information and click OK Select File gt Save or press Ctrl S to save the changes to the etc hosts file The network or network services do not need to be restarted since the current version of the file is referred to each time an address is resolved Warning Do not remove the localhost entry Even if the system does not have a network connection or have a network connection running constantly some programs need to connect to the system via the localhost loopback interface 180 Working with Profiles File Profile Help it f New Edit Copy Delete Host You may specify static computer hostname to IP address mappings here If DNS is in use these settings will take precedence over any information it may provide Figure 17 15 Hosts Configuration Tip To change lookup order edit the etc host conf file The line order hosts bind specifies that etc hosts takes precedence over the name servers Changing the line to order bind
317. n Mode User Authentication Server Kerberos Realm Encrypt Passwords Yes Guest Account No guest account Figure 22 3 Configuring Security Server Settings The Security tab contains the following options e Authentication Mode This corresponds to the security option Select one of the following types of authentication e ADS The Samba server acts as a domain member in an Active Directory Domain ADS realm For this option Kerberos must be installed and configured on the server and Samba must become a member of the ADS realm using the net utility which is part of the samba client package Refer to the net man page for details This option does not configure Samba to be an ADS Controller Specify the realm of the Kerberos server in the Kerberos Realm field Note The Kerberos Realm field must be supplied in all uppercase letters such as EXAMPLE COM 233 Chapter 22 Samba Use of your Samba server as a domain member in an ADS realm assumes proper configuration of Kerberos including the etc krb5 conf file e Domain The Samba server relies on a Windows NT Primary or Backup Domain Controller to verify the user The server passes the username and password to the Controller and waits for it to return Specify the NetBIOS name of the Primary or Backup Domain Controller in the Authentication Server field The Encrypted Passwords option must be set to Ye
318. n controller User information can be accessed as well as 290 Authentication server authentication options can be configured Cache User Information Select this option to enable the name service cache daemon nscd and configure it to start at boot time The nscd package must be installed for this option to work 2 Authentication The Authentication tab allows for the configuration of network authentication methods To enable an option click the empty checkbox beside it To disable an option click the checkbox beside it to clear the checkbox User Information Authentication Kerberos SMB Kerberos is a trusted third party authentication system SMB authentication verifies user passwords by which is commonly used in medium to large networks attempting to connect to a server which uses the SMB system message block protocol suite Enable Kerberos Support Configure Kerberos Enable SMB Support Configure SMB LDAP The Lightweight Directory Access Protocol is a Winbind standard way of searching a directory which can hold Winbind allows a system to retrieve information about users arbitrary data in a structured hierarchy LDAP is and to authenticate users by using information stored in an increasingly being used in small to large networks NTDOM or ADS server It is used in small to large networks C Enable LDAP Support Configure LDAP C Enable
319. n is selected when the file is saved the 39 Chapter 2 Kickstart Configurator plain text password that you typed are encrypted and written to the kickstart file If type an already encrypted password unselect to encrypt it If Upgrade an existing installation is selected on the Installation Method page select Upgrade existing boot loader to upgrade the existing boot loader configuration while preserving the old entries 4 Partition Information File Help Basic Configuration Partition Information required Installation Method Clear Master Boot Record Boot Loader Options Do not clear Master Boot Record Partition Information Remove all existing partitions Network Configuration Remove existing Linux partitions Authentication Preserve existing partitions Firewall Configuration Initialize the disk label Display Configuration Do not initialize the disk label Package Selection Device Mount Point T F t Size MB Pre Installation Script Partition Number RAID ype Format size Post Installation Script Add Edit Delete RAID Figure 2 4 Partition Information Select whether or not to clear the Master Boot Record MBR Choose to remove all existing partitions remove all existing Linux partitions or preserve existing partitions To initialize the disk label to the default for the architecture of the system for example msdos for x86 and gpt for Itanium select Initialize the disk lab
320. nA AE A aaa aSa 75 1 Features OFE 2 ccc cece cece ee rika denria erene EEEREN riU AKE CENNE Reena REEK E 75 2 Creating an ext3 File System cceceeeceeeeeeeeeeeeeeeeeaaeaeeeeeeeeeeaeaaeaneeeeeees 76 3 Converting to an ext3 File System 0 cece ce eeceeeee cece ae eeeeeeeeeeeeeeaaeaeeeeeeees 76 4 Reverting to an ext2 File System 00 0 0 cccceeeeeeeee cece ee eeeeeeeeeeeeeeeeaaaaneeeeeees 77 7 Logical Volume Manager LVM 0 ccceceeeeeeeeeeeeeeeeeeaeaaeeeeeeeeeeeeaeaaaaneeeeeees 79 Te What iS CVM a tecocctinncesesstezercssnaaueeeshecocseasinuerestvncedbanraseeestveceeieshaudeusduees 79 2 Whats LV M2 csteceacnsteescacaneceneetan fuged enecenceiedegaaPadeventecutaeiabedeces catteasaatane 80 3 Additional RESOUICES eee ce ceeeceeeneeeeeee ea eeeeeeaaeeeeeeaaeeeeeeaaeeeeeeaaeeeeeeaaanees 80 3 1 Installed Documentation scssssssnorasenicicarn 80 3 2 Useful Websites 22 2 ccccccseeit seek sestenie iets eetbeeee ent eeee eed eneeenae dente 81 8 LVM Configuration shcsnce ei dabei eet eve ee ees 83 1 Automatic Partitioning iccis secccessteveddasadenneas savoteas K AKR EARS EAA AE 83 2 Manual LVM Partitioning seanssi E R 85 2 1 Creating the boot Partition ccecececeeeeeeeeeeeeeeeeeaeeaeeeeeeeeeeeeaed 85 2 2 Creating the LVM Physical Volumes 0 ceeeeeeeeeeeeeeeeeeeeeeeaes 88 2 3 Creating the LVM Volume Groups eceeeeeeeeeeeeeeeeeeeeeeeeeaea 90 2 4 Crea
321. nd IP address combinations To use the Network Administration Tool you must have root privileges To start the application go to the Applications the main menu on the panel gt System Settings gt Network or type the command system config network at a shell prompt for example in an XTerm or a GNOME terminal If you type the command the graphical version is displayed if X is running otherwise the text based version is displayed To use the command line version execute the command system config network cmd help as root to view all of the options 161 Chapter 17 Network Configuration File Profile Help s f Be X New Edit Copy Delete Activate Deactivate physical hardware here Multiple logical devices can be associated with a single piece of hardware a A Inactive ethl1 ethl Ethernet n amp Active etho Ethernet Figure 17 1 Network Administration Tool Tip Use the Red Hat Hardware Compatibility List http hardware redhat com hcl to determine if Red Hat Enterprise Linux supports your hardware device 1 Overview To configure a network connection with the Network Administration Tool perform the following steps 162 Establishing an Ethernet Connection 1 Add a network device associated with the physical hardware device 2 Add the physical hardware device to the hardware list if it does not already exist 3 Configure the hostname and DNS settings 4 Configure a
322. ndriusb 24 4 MB 401K 0 18404 gnome settings daemon andriusb 19 4 MB 0 bytes 0 18360 gnome system monitor andriusb 23 1 MB 1 4 MB 0 18440 gnome vfs daemon andriusb 21 0 MB 0 bytes 0 18421 gnome volume manager andriusb 19 0 MB 0 bytes 0 18408 mapping daemon andriusb 2 9 MB 0 bytes 0 18429 metacity andriusb 14 4 MB 0 bytes 0 18399 381 Chapter 39 Gathering System Figure 39 1 GNOME System Monitor 2 Memory Usage The free command displays the total amount of physical memory and swap space for the system as well as the amount of memory that is used free shared in kernel buffers and cached total used fr shared buffers cached Mem 645712 549720 95992 0 176248 224452 buffers cache 149020 496692 Swap 1310712 0 1310712 The command free m shows the same information in megabytes which are easier to read total used fr ShoarcodibunrterskedehediMen 4510 Scie Ss 1 wy2 Ail c buffers cache 145 485 Swap 1279 0 1279 If you prefer a graphical interface for free you can use the GNOME System Monitor To start it from the desktop go to System gt Administration gt System Monitor or type gnome system monitor ata shell prompt such as an XTerm Click on the Resources tab 382 File Systems File Edit View Help Process Listing Resource Monitor CPU History EE CPU1 16 0 Memory and Swap History
323. ne select this check box Note that an improperly configured SMTP server can allow remote machines to use your server to send spam NFS4 The Network File System NFS is a file sharing protocol commonly used on NIX systems Version 4 of this protocol is more secure than its predecessors If you want to share files or directories on your system with other network users select this check box Samba Samba is an implementation of Microsoft s proprietary SMB networking protocol If you need to share files directories or locally connected printers with Microsoft Windows machines select this check box 2 4 Other Ports The Security Level Configuration Tool includes an Other ports section for specifying custom IP ports as being trusted by iptables For example to allow IRC and Internet printing protocol IPP to pass through the firewall add the following to the Other ports section 194 tcp 631 tcp 2 5 Saving the Settings Click OK to save the changes and enable or disable the firewall If Enable firewall was selected the options selected are translated to iptables commands and written to the etc sysconfig iptables file The iptables service is also started so that the firewall is activated immediately after saving the selected options If Disable firewall was selected the etc sysconfig iptables file is removed and the iptables service is stopped immediately The selected options are also written to the etc sysconfig system config se
324. ne of ext2 ext3 fat16 fat32 hfs jfs linux swap ntfs reiserfs hp ufs sun ufs or xfs The Flags column lists the flags set for the partition Available flags are boot root swap hidden raid Ivm or Iba In this example minor number 1 refers to the boot file system minor number 2 refers to the root file system minor number 3 refers to the swap and minor number 5 refers to the home file system Tip To select a different device without having to restart partea use the select command followed by the device name such as dev sda Then you can view its partition table or configure it 1 2 Creating a Partition Warning d Do not attempt to create a partition on a device that is in use Before creating a partition boot into rescue mode or unmount any partitions on the device and turn off any swap space on the device Start parted where dev sda is the device on which to create the partition parted dev sda View the current partition table to determine if there is enough free space penne If there is not enough free space you can resize an existing partition Refer to Section 1 4 Resizing a Partition for details 117 Chapter 12 Managing Disk Storage 1 2 1 Making the Partition From the partition table determine the start and end points of the new partition and what partition type it should be You can only have four primary partitions with no extended partition on a device
325. nfigure LDAP C Enable Winbind Support Configure Winbind Cache User Information X Cancel 2 OK Figure 26 1 User Information The following list explains what each option configures Enable NIS Support Select this option to configure the system as an NIS client which connects to an NIS server for user and password authentication Click the Configure NIS button to specify the NIS domain and NIS server If the NIS server is not specified the daemon attempts to find it via broadcast The ypbind package must be installed for this option to work If NIS support is enabled the portmap and ypbind services are started and are also enabled to start at boot time Enable LDAP Support Select this option to configure the system to retrieve user information via LDAP Click the Configure LDAP button to specify the LDAP Search Base DN and LDAP Server If Use TLS to encrypt connections is selected Transport Layer Security is used to encrypt passwords sent to the LDAP server The openldap clients package must be installed for this option to work For more information about LDAP refer to the Red Hat Enterprise Linux Reference Guide Enable Hesiod Support Select this option to configure the system to retrieve information from a remote Hesiod database including user information The hesiod package must be installed Winbind Select this option to configure the system to connect to a Windows Active Directory or a Windows domai
326. nformation 4 1 Installed Documentation e The ssh scp sftp sshd and ssh keygen man pages These man pages include information on how to use these commands as well as all the parameters that can be used with them 4 2 Useful Websites hitp www openssh com The OpenSSH FAQ page bug reports mailing lists project goals and a more technical explanation of the security features http www openssl org The OpenSSL FAQ page mailing lists and a description of the project goal htto www treessh org SSH client software for other platforms 4 3 Related Books e Red Hat Enterprise Linux Reference Guide Learn the event sequence of an SSH connection review a list of configuration files and discover how SSH can be used for X forwarding 220 Chapter 21 Network File System NFS Network File System NFS is a way to share files between machines on a network as if the files were located on the client s local hard drive Red Hat Enterprise Linux can be both an NFS server and an NFS client which means that it can export file systems to other systems and mount file systems exported from other machines 1 Why Use NFS NFS is useful for sharing directories of files between multiple users on the same network For example a group of users working on the same project can have access to the files for that project using a shared directory of the NFS file system commonly known as an NFS share mounte
327. nguage Support list The language selected from the Default Language pulldown menu is used by default after installation however the default can be changed with the Language Configuration Tool syst em config language after installation Choosing Target Architecture specifies which specific hardware architecture distribution is used during installation Choosing Reboot system after installation reboots your system automatically after the installation is finished Kickstart installations are performed in graphical mode by default To override this default and use text mode instead select the Perform installation in text mode option You can perform a kickstart installation in interactive mode This means that the installation program uses all the options pre configured in the kickstart file but it allows you to preview the options in each screen before continuing to the next screen To continue to the next screen click the Next button after you have approved the settings or change them before continuing the installation To select this type of installation select the Perform installation in interactive mode option 2 Installation Method 36 Installation Method File Help Basic Configuration Installation Method required Perform new installation Boot Loader Options Upgrade an existing installation Partition Information Choose the Installation Method Network Configuration CD ROM Authentication O NFS Firewall C
328. nnium II Matrox Mystique p Matrox Mystique G200 Matrox Productiva G100 MediaVision Proaxcel 128 Mirage Z 128 Miro CRYSTAL VRX Miro Crystal 10SD with GenDAC Video Card RAM 32 MB Figure 2 12 X Configuration Video Card 8 3 Monitor After configuring the video card click on the Monitor tab as shown in Figure 2 13 X Configuration Monitor 50 Package Selection File Help Basic Configuration Display Configuration Installation Method Configure the X Window System Boot Loader Options General Video Card Monitor Partition Information Cimrebe tin mention Network Configuration g Monitor 640x480 Authentication i Monitor 800x600 Firewall Configuration Monitor 1024x768 Display Configuration i Monitor 1280x1024 Package Selection f Monitor 1400x1050 Monitor 1600x1200 LCD Panel 640x480 LCD Panel 800x600 LCD Panel 1024x768 LCD Panel 1280x800 LCD Panel 1400x1050 LCD Panel 1440x900 LCD Panel 1600x1200 C Use custom monitor sync rates Pre Installation Script Post Installation Script Horizontal Sync Hz Vertical Sync kHz Figure 2 13 X Configuration Monitor Probe for monitor is selected by default Accept this default to have the installation program probe for the monitor during installation Probing works for most modern monitors If this option is selected and the installation program c
329. not effective unless the kickstart file is a local file such as ks floppy since the installation program configures the network to find the kickstart file For example network bootproto dhcp device eth0 ip IP address for the machine to be installed gateway Default gateway as an IP address nameserver Primary nameserver as an IP address nodns Do not configure any DNS server netmask Netmask for the installed system hostname Hostname for the installed system part Or partition required for installs ignored for upgrades Creates a partition on the system If more than one Red Hat Enterprise Linux installation exists on the system on different 16 Kickstart Options partitions the installation program prompts the user and asks which installation to upgrade Warning 4 All partitions created are formatted as part of the installation process unless J noformat and onpart are used For a detailed example of part in action refer to Section 4 1 Advanced Partitioning Example lt mntpoint gt The lt mntpoint gt is where the partition is mounted and must be of one of the following forms e lt path gt For example usr home swap The partition is used as swap space To determine the size of the swap partition automatically use the recommended option swap recommended The minimum size of the automatically generated swap p
330. not be booted into Red Hat Enterprise Linux without working boot media For example to create a boot diskette login as root and type the following command at a shell prompt sbin mkbootdisk uname r Tip Refer to the mkbootdisk man page for more options Creating bootable media via CD Rs CD RWs and USB flash drives are also supported given the system BIOS also supports it Reboot the machine with the boot media and verify that it works before continuing Hopefully the media is not needed but store it in a safe place just in case To determine which kernel packages are installed execute the following command at a shell prompt rpm qa grep kernel The output contains some or all of the following packages depending on the system s architecture the version numbers and packages may differ kernel 2 6 9 5 EL kernel devel 2 6 9 5 EL kernel utils 2 6 9 5 EL kernel doc 2 6 9 5 EL kernel smp 2 6 9 5 EL kernel smp devel 2 69 5 EL kernel hugemem devel 2 6 9 5 EL From the output determine which packages need to be download for the kernel upgrade For a single processor system the only required package is the kernel package Refer to Section 1 Overview of Kernel Packages for descriptions of the different packages 363 Chapter 36 Manually Upgradin In the file name each kernel package contains the architecture for which the package was built The format is kernel lt variant
331. not contain any partitions in use system processes that use or lock the file system from being unmounted you can unmount them with the umount command and turn off all the swap space on the hard drive with the swapoff command Table 12 1 parted commands contains a list of commonly used parted commands The sections that follow explain some of them in more detail Command Description check minor num Perform a simple check of the file system cp fromto Copy file system from one partition to another from and to are the minor numbers of the partitions help Display list of available commands mklabel label Create a disk label for the partition table mkfs minor numfile system typ Create a file system of type file system type mkpart part typefs typestart mbend mb Make a partition without creating a new file system 115 Chapter 12 Managing Disk Storage Command Description mkpartfs part typefs typestart mbend mb Make a partition and create the specified file system move minor numstart mbend mb Move the partition name minor numname Name the partition for Mac and PC98 disklabels only print Display the partition table quit Quit parted rescuestart mbend mb Rescue a lost partition from start mb to end mb resize minor numstart mbend mb Resize the partition from start mb to end mb rm mino
332. nstead of the system s hard drive As the name implies rescue mode is provided to rescue you from something During normal operation your Red Hat Enterprise Linux system uses files located on your system s hard drive to do everything run programs store your files and more However there may be times when you are unable to get Red Hat Enterprise Linux running completely enough to access files on your system s hard drive Using rescue mode you can access the files stored on your system s hard drive even if you cannot actually run Red Hat Enterprise Linux from that hard drive To boot into rescue mode you must be able to boot the system using one of the following methods e By booting the system from an installation boot CD ROM e By booting the system from other installation boot media such as USB flash devices e By booting the system from the Red Hat Enterprise Linux CD ROM 1 Once you have booted using one of the described methods add the keyword rescue as a kernel parameter For example for an x86 system type the following command at the installation boot prompt linux rescue You are prompted to answer a few basic questions including which language to use It also prompts you to select where a valid rescue image is located Select from Local CD ROM Hard Drive NFS image FTP or HTTP The location selected must contain a valid installation tree and the installation tree must be for the same version of Red Hat Enterprise
333. ntains the application used to prompt you for your passphrase when you log in to GNOME and save it until you log out of GNOME You will not have to enter your password or passphrase for any ssh or scp connection made during that GNOME session If you are not using GNOME refer to Section 3 4 5 Configuring ssh agent To save your passphrase during your GNOME session follow the following steps 1 You will need to have the package openssh askpass gnome installed you can use the command rpm q openssh askpass gnome to determine if it is installed or not If it is not installed install it from your Red Hat Enterprise Linux CD ROM set from a Red Hat FTP mirror site or using Red Hat Network 2 Select Main Menu Button on the Panel gt Preferences gt More Preferences gt Sessions and click on the Startup Programs tab Click Add and enter usr bin ssh add in the Startup Command text area Set it a priority to a number higher than any existing commands to ensure that it is executed last A good priority number for ssh add is 70 or higher The higher the priority number the lower the priority If you have other programs listed this one should have the lowest priority Click Close to exit the program 3 Log out and then log back into GNOME in other words restart X After GNOME is started a dialog box will appear prompting you for your passphrase s Enter the passphrase requested If you have both DSA and RSA key pairs configured you
334. number of events between each sample snapshot When setting the event for the counter a sample rate can also be specified opcontrol event lt event name gt lt sample rate gt Replace lt sample rate gt with the number of events to wait before sampling again The smaller the count the more frequent the samples For events that do not happen frequently a lower count may be needed to capture the event instances A Caution Be extremely careful when setting sampling rates Sampling too frequently can overload the system causing the system to appear as if it is frozen or causing the system to actually freeze 391 Chapter 40 OProfile 2 2 2 Unit Masks If the cpu_type is not timer unit masks may also be required to further define the event Unit masks for each event are listed with the op_help command The values for each unit mask are listed in hexadecimal format To specify more than one unit mask the hexadecimal values must be combined using a bitwise or operation opcontrol vent lt event name gt lt sample rate gt lt unit mask gt 2 3 Separating Kernel and User space Profiles By default kernel mode and user mode information is gathered for each event To configure OProfile not to count events in kernel mode for a specific counter execute the following command opcontrol vent lt event name gt lt sample rate gt lt unit mask gt 0 Execute the following command
335. nvironment Click Forward 3 Enter the IP address or domain name of the NFS server configured in Section 1 Configuring the NFS Server as well as the directory exported as the diskless environment Click Forward 4 The kernel versions installed in the diskless environment are listed Select the kernel version to boot on the diskless system 5 Click Apply to finish the configuration After clicking Apply the diskless kernel and image file are created based on the kernel selected They are copied to the PXE boot directory tftpboot linux install lt os identifier gt The directory snapshot is created in the same directory as the root directory for example diskless i386 RHEL4 AS snapshot with a file called files in it This file contains a list of files and directories that must be read write for each diskless system Do not modify this file If additional entries must be added to the list create a files custom file in the same directory as the files file and add each additional file or directory on a separate line 3 Adding Hosts Each diskless client must have its own snapshot directory on the NFS server that is used as its read write file system The Network Booting Tool can be used to create these snapshot directories After completing the steps in Section 2 Finish Configuring the Diskless Environment a window appears to allow hosts to be added for the diskless environment Click the New button In the dial
336. ny hosts that cannot be looked up through DNS This chapter discusses each of these steps for each type of network connection 2 Establishing an Ethernet Connection To establish an Ethernet connection you need a network interface card NIC a network cable usually a CAT5 cable and a network to connect to Different networks are configured to use different network speeds make sure your NIC is compatible with the network to which you want to connect To add an Ethernet connection follow these steps 1 Click the Devices tab 2 Click the New button on the toolbar 3 Select Ethernet connection from the Device Type list and click Forward 4 If you have already added the network interface card to the hardware list select it from the Ethernet card list Otherwise select Other Ethernet Card to add the hardware device Note The installation program detects supported Ethernet devices and prompts you to configure them If you configured any Ethernet devices during the installation they are displayed in the hardware list on the Hardware tab 5 If you selected Other Ethernet Card the Select Ethernet Adapter window appears Select the manufacturer and model of the Ethernet card Select the device name If this is the system s first Ethernet card select ethO as the device name if this is the second Ethernet card select eth1 and so on The Network Administration Tool also allows you to configure the resources for the NIC Clic
337. o Trusted devices C sit Other ports dozer Figure 18 1 Security Level Configuration Tool Note The Security Level Configuration Tool only configures a basic firewall 2 2 Enabling and Disabling the Firewall Select one of the following options for the firewall e Disabled Disabling the firewall provides complete access to your system and does no 192 Trusted Services security checking This should only be selected if you are running on a trusted network not the Internet or need to configure a custom firewall using the iptables command line tool Warning Firewall configurations and any customized firewall rules are stored in the etc sysconfig iptables file If you choose Disabled and click OK these configurations and firewall rules will be lost Enabled This option configures the system to reject incoming connections that are not in response to outbound requests such as DNS replies or DHCP requests If access to services running on this machine is needed you can choose to allow specific services through the firewall If you are connecting your system to the Internet but do not plan to run a server this is the safest choice 2 3 Trusted Services Enabling options in the Trusted services list allows the specified service to pass through the firewall WWW HTTP The HTTP protocol is used by Apache and by other Web servers to serve web pages If you plan on making your Web server
338. o set each Samba user s password use the following command replace username with each user s username smbpasswd username 4 Encrypted passwords must be enabled Since they are enabled by default they do not have to be specifically enabled in the configuration file However they can not be disabled in the configuration file either In the file etc samba smb conf verify that the following line does not exist encrypt passwords no If it does exist but is commented out with a semi colon at the beginning of the line then the line is ignored and encrypted passwords are enabled If this line exists but is not commented out either remove it or comment it out To specifically enable encrypted passwords in the configuration file add the following lines to etc samba smb conf encrypt passwords yes smb passwd file etc samba smbpasswd 5 Make sure the smb service is started by typing the command service smb restart ata shell prompt 6 If you want the smb service to start automatically use ntsysv chkconfig or the Services 238 Starting and Stopping the Server Configuration Tool to enable it at runtime Refer to Chapter 19 Controlling Access to Services for details The pam_smbpass PAM module can be used to sync users Samba passwords with their system passwords when the passwd command is used If a user invokes the passwd command the password he uses to log in to the Red Hat Enterprise Linux system as well
339. o that the files can be copied to the NFS server Refer to the Red Hat Enterprise Linux Installation Guide for details Any software to be used on the clients must be installed on this system and the busybox anaconda package must be installed 2 Create a directory on the NFS server to contain the diskless environment such as diskless i386 RHEL4 AS For example mkdir p diskless i386 RHEL4 AS This directory is referred to as the diskless directory 3 Create a subdirectory of this directory named root mkdir p diskless i386 RHEL4 AS root 4 Copy Red Hat Enterprise Linux from the client system to the server using rsync For example rsync a e ssh installed system example com diskless i386 RHEL4 AS root The length of this operation depends on the network connection speed as well as the size of the file system on the installed system Depending on these factors this operation may take a while 5 Start the tftp server 6 Configure the DHCP server 7 Finish creating the diskless environment as discussed in Section 2 Finish Configuring the 63 Chapter 4 Diskless Environments Diskless Environment 8 Configure the diskless clients as discussed in Section 3 Adding Hosts 9 Configure each diskless client to boot via PXE and boot them 1 Configuring the NFS Server The shared read only part of the operating system is shared via NFS Configure NFS to export the root
340. o use this option rpm q redhatprovides bar so 2 If the package that contains bar so 2 is in the installed database from the rpmdb redhat package the name of the package is displayed par 2P0P Or 1 BEG wom To force the installation anyway which is not recommended since the package may not run correctly use the nodeps option 2 3 Uninstalling Uninstalling a package is just as simple as installing one Type the following command at a shell prompt rpm e foo Note Notice that we used the package namefoo not the name of the original package filefo0 1 0 1 i386 rpm To uninstall a package replace foo with the actual package name of the original package 145 Chapter 15 Package Managemen You can encounter a dependency error when uninstalling a package if another installed package depends on the one you are trying to remove For example error Failed dependencies foo is needed by installed bar 2 0 20 3 1386 rpm To cause RPM to ignore this error and uninstall the package anyway which may break the package depending on it use the nodeps option 2 4 Upgrading Upgrading a package is similar to installing one Type the following command at a shell prompt wom win tOO 2 0 1 1S86 comm As part of upgrading a package RPM automatically uninstalls any old versions of the foo package In fact you may want to always use u to install packages which works even when there are no previo
341. odule for the card If a card is added after installation Kudzu should recognize it and prompt for the configuration of the corresponding kernel module for it Be sure to check the Hardware Compatibility List available at http hardware redhat com hcl lf the network card is not configured by the installation program or Kudzu and you know which kernel module to load for it refer to Chapter 37 Kernel Modules for details on loading kernel modules 1 Kudzu is a hardware probing tool run at system boot time to determine what hardware has been added or removed from the system 251 Chapter 23 Dynamic Host Conf To configure a DHCP client manually modify the etc sysconfig network file to enable networking and the configuration file for each network device in the etc sysconfig network scripts directory In this directory each device should have a configuration file named ifcfg etho where etno is the network device name The etc sysconfig network file should contain the following line NETWORKING yes The NETWORKING variable must be set to yes if you want networking to start at boot time The etc sysconfig network scripts ifcfg etho file should contain the following lines DEVICE eth0O BOOTPROTO dhcp ONBOOT yes A configuration file is needed for each device to be configured to use DHCP Other options for the network script include DHCP_HOSTNAME Only use this option if the DHCP server requires
342. of the interface to the list of DHCPDARGS Command line options here DHCPDARGS eth0O This is useful for a firewall machine with two network cards One network card can be configured as a DHCP client to retrieve an IP address to the Internet The other network card can be used as a DHCP server for the internal network behind the firewall Specifying only the network card connected to the internal network makes the system more secure because users can not connect to the daemon via the Internet Other command line options that can be specified in etc sysconfig dhcpd include 250 DHCP Relay Agent e p lt portnum gt Specify the UDP port number on which dhcpd should listen The default is port 67 The DHCP server transmits responses to the DHCP clients at a port number one greater than the UDP port specified For example if the default port 67 is used the server listens on port 67 for requests and responses to the client on port 68 If a port is specified here and the DHCP relay agent is used the same port on which the DHCP relay agent should listen must be specified Refer to Section 2 4 DHCP Relay Agent for details e f Run the daemon as a foreground process This is mostly used for debugging q Log the DHCP server daemon to the standard error descriptor This is mostly used for debugging If this is not specified the log is written to var log messages e cf lt filename gt Specify the location of th
343. og shown in Figure 4 1 Add Diskless Host provide the following information Hostname or IP Address Subnet Specify the hostname or IP address of a system to add it as a host for the diskless environment Enter a subnet to specify a group of systems Operating System Select the diskless environment for the host or subnet of hosts Serial Console Select this checkbox to perform a serial installation Snapshot name Provide a subdirectory name to be used to store all of the read write content for the host Ethernet Select the Ethernet device on the host to use to mount the diskless environment If the host only has one Ethernet card select etho Ignore the Kickstart File option It is only used for PXE installations 65 Chapter 4 Diskless Environments Hostname or IP Address Subnet 192 168 1 1 C Serial Console Diskless OS Network OS Install Snapshot name test Kickstart File Figure 4 1 Add Diskless Host In the existing snapshot directory in the diskless directory a subdirectory is created with the Snapshot name specified as the file name Then all of the files listed in snapshot files and snapshot files custom are copied copy from the root directory to this new directory 4 Booting the Hosts Consult the documentation for your PXE card to configure the host to boot via PXE When the diskless client boots it mounts the remote root directory in the diskless directory as read
344. oint gt level lt level gt device lt mddevice gt lt partitions gt lt mntpoint gt Location where the RAID file system is mounted If it is the RAID level must be 1 unless a boot partition boot is present If a boot partition is present the boot partition must be level 1 and the root partition can be any of the available types The lt partitions gt which denotes that multiple partitions can be listed lists the RAID identifiers to add to the RAID array level RAID level to use 0 1 or 5 device Name of the RAID device to use Such as mdO or md1 RAID devices range from mdO to md7 and each may only be used once spares Specifies the number of spare drives allocated for the RAID array Spare drives are used to rebuild the array in case of drive failure fstype Sets the file system type for the RAID array Valid values are ext2 ext3 swap and vfat noformat Use an existing RAID device and do not format the RAID array useexisting Use an existing RAID device and reformat it The following example shows how to create a RAID level 1 partition for and a RAID level 5 for usr assuming there are three SCSI disks on the system It also creates three swap partitions one on each drive 19 Chapter 1 Kickstart Installa part raid 01 size 60 ondisk sda part raid 02 size 60 ondisk sdb part raid 03 size 60 ondisk sdc
345. ollowing steps to generate an RSA key pair for version 2 of the SSH protocol This is the default starting with OpenSSH 2 9 1 To generate an RSA key pair to work with version 2 of the protocol type the following command at a shell prompt ssh keygen t rsa Accept the default file location of ssh id_rsa Enter a passphrase different from your account password and confirm it by entering it again 216 Generating Key Pairs The public key is written to ssh id_rsa pub The private key is written to ssh id_rsa Never distribute your private key to anyone 2 Change the permissions of the ssh directory using the following command Caneel 755 sala 3 Copy the contents of ssh id_rsa pub into the file ssh authorized_keys on the machine to which you want to connect If the file ssh authorized_keys exist append the contents of the file ssh id_rsa pub to the file ssh authorized_keys on the other machine 4 Change the permissions of the authorized_keys file using the following command chmod 644 ssh authorized_keys 5 If you are running GNOME skip to Section 3 4 4 Configuring ssh agent with GNOME If you are not running the X Window System skip to Section 3 4 5 Configuring ssh agent 3 4 2 Generating a DSA Key Pair for Version 2 Use the following steps to generate a DSA key pair for version 2 of the SSH Protocol 1 To generate a DSA key pair to work with version 2 of the protoco
346. ommand Line Configuration 57 Chapter 3 PXE Network Instal To use the graphical version of the Network Booting Tool you must be running the X Window System have root privileges and have the system config netboot RPM package installed To start the Network Booting Tool from the desktop go to Applications the main menu on the panel gt System Settings gt Server Settings gt Network Booting Service Or type the command system config netboot at a shell prompt for example in an XTerm or a GNOME terminal If starting the Network Booting Tool for the first time select Network Install from the First Time Druid Otherwise select Configure gt Network Installation from the pulldown menu and then click Add The dialog in Figure 3 1 Network Installation Setup is displayed Operating system identifier rhel4 as Description RHEL4 AS Select protocol for installation Kickstart http www example com ks ks cfg Software Server server example com Location misc RHEL4 AS i386 tree Anonymous FTP User Password Jo Figure 3 1 Network Installation Setup Operating system identifier Provide a unique name using one word to identify the Red Hat Enterprise Linux version and variant It is used as the directory name in the tftpboot linux install directory e Description Provide a brief description of the Red Hat Enterprise Linux version and variant Selects protocol for inst
347. ommand Line Options for star 6 Compatibility with Older Systems If an ACL has been set on any file on a given file system that file system has the ext_attr attribute This attribute can be seen using the following command tune2fs 1 lt filesystem device gt A file system that has acquired the ext_attr attribute can be mounted with older kernels but those kernels do not enforce any ACLs which have been set Versions of the e2fsck utility included in version 1 22 and higher of the e2fsprogs package including the versions in Red Hat Enterprise Linux 2 1 and 5 0 0 can check a file system with the ext_attr attribute Older versions refuse to check it 7 Additional Resources Refer to the follow resources for more information 7 1 Installed Documentation acl man page Description of ACLs e getfacl man page Discusses how to get file access control lists setfacl man page Explains how to set file access control lists star man page Explains more about the star utility and its many options 7 2 Useful Websites http acl bestbits at Website for ACLs 137 138 Part Ill Package Management All software on a Red Hat Enterprise Linux system is divided into RPM packages which can be installed upgraded or removed This part describes how to manage the RPM packages ona Red Hat Enterprise Linux system using graphical and command line tools Chapter 15 Package Management with RPM
348. on oo eee eee eeee anana 335 33 Printer Configuration cece ceeeeeeeee cece ee eeee cece sees ee aaeaeeeeeeeeeeeeaaaaeeeeeeeeeeeeaaa 337 1 Adding a Local Printer 2 00 0 cee ccc eeeeeeneeeeee na eeeeeeaaeeeeeeaaeeeeeeaaeeeeeeaaeeees 338 2 Adding an IPP Printer ccceccseeeeeceeeee rece S 339 3 Adding a Samba SMB Printer cececcceeeeeeeeeeeeeeeaeeeeeeeeeeeeeeeanaaeeees 340 4 Adding a JetDirect Printer 20 2 0 cece ceeeeeeeeeee eter cena eeeeaaeeeeeeaaaeeeeeaaeeees 342 5 Selecting the Printer Model and Finishing c eceeeeeeeeeeeeeeeeeeeeeaee 343 5 1 Confirming Printer Configuration ccceeceeeeeeeeeeeeeeeaaeeeeeeeeees 344 6 Printing a Test Page 200 ce ceceee cece ete eeee eee ee eeeeaeeeeeeeeeeeeeeeeaeeeeaaeaeeeeanees 344 7 Modifying Existing Printers 10 0 ceccceeeeeeeeeeeeeeeeeeeeeeeaeeeeeeeaeeeeeaeeaeeeeaeaes 344 7 1 The Settings Tab i echcceneiie eed anand eeiondiests 344 2 The Policies Tab i4 0 c nc0l sien Adee 344 7 3 The Access Control Tab 00 cceccceeeeeeeeeeeeeeeeeeeeeaeaaeaeeeeeees 345 7 4 The Printer and Job OptionsTab c eee 345 8 Managing Print JODS 00 eee eee eee ee cece i een irienn REEN ENERE 346 9 Additional RESOUICES acs see manar ea EE ES 346 9 1 Installed Documentation 2 0 cece ee eeeeeeeeeeeeeeeeeeeeeeeeeeaeeeeeaaees 347 9 2 Useful Websites 2 250 i lesetis ive esis OA 347 34 Automated Tasks ssctc
349. onfiguration LVM can be configured during the graphical installation process the text based installation process or during a kickstart installation You can use the utilities from the 1vm package to create your own LVM configuration post installation but these instructions focus on using Disk Druid during installation to complete this task Read Chapter 7 Logical Volume Manager LVM first to learn about LVM An overview of the steps required to configure LVM include e Creating physical volumes from the hard drives Creating volume groups from the physical volumes Creating logical volumes from the volume groups and assign the logical volumes mount points Note Although the following steps are illustrated during a GUI installation the same can be done during a text based installation Two 9 1 GB SCSI drives dev sda and dev sdb are used in the following examples They detail how to create a simple configuration using a single LVM volume group with associated logical volumes during installation 1 Automatic Partitioning On the Disk Partitioning Setup screen select Automatically partition For Red Hat Enterprise Linux LVM is the default method for disk partitioning If you do not wish to have LVM implemented or if you require RAID partitioning manual disk partitioning through Disk Druid is required The following properties make up the automatically created configuration e The boot partition resides on its o
350. onfiguration O FTP Display Configuration O HTTP Package Selection Hard Drive Pre Installation Script Post Installation Script Figure 2 2 Installation Method The Installation Method screen allows you to choose whether to perform a new installation or an upgrade If you choose upgrade the Partition Information and Package Selection options are disabled They are not supported for kickstart upgrades Choose the type of kickstart installation or upgrade screen from the following options CD ROM Choose this option to install or upgrade from the Red Hat Enterprise Linux CD ROMs e NFS Choose this option to install or upgrade from an NFS shared directory In the text field for the the NFS server enter a fully qualified domain name or IP address For the NFS directory enter the name of the NFS directory that contains the RedHat directory of the installation tree For example if the NFS server contains the directory mirrors redhat i386 RedHat enter mirrors redhat i386 for the NFS directory 37 Chapter 2 Kickstart Configurator FTP Choose this option to install or upgrade from an FTP server In the FTP server text field enter a fully qualified domain name or IP address For the FTP directory enter the name of the FTP directory that contains the RedHat directory For example if the FTP server contains the directory mirrors redhat i386 RedHat enter mirrors redhat i386 for the FTP directory If the
351. only It also mounts its individual snapshot directory as read write Then it mounts all the files and directories in the files and files custom files using the mount o bind over the read only diskless directory to allow applications to write to the root directory of the diskless environment if they need to 66 Chapier 5 Basic System Recovery When things go wrong there are ways to fix problems However these methods require that you understand the system well This chapter describes how to boot into rescue mode single user mode and emergency mode where you can use your own knowledge to repair the system 1 Common Problems You might need to boot into one of these recovery modes for any of the following reasons e You are unable to boot normally into Red Hat Enterprise Linux runlevel 3 or 5 You are having hardware or software problems and you want to get a few important files off of your system s hard drive e You forgot the root password 1 1 Unable to Boot into Red Hat Enterprise Linux This problem is often caused by the installation of another operating system after you have installed Red Hat Enterprise Linux Some other operating systems assume that you have no other operating system s on your computer They overwrite the Master Boot Record MBR that originally contained the GRUB boot loader If the boot loader is overwritten in this manner you cannot boot Red Hat Enterprise Linux unless you can get into re
352. ool system config netboot 57 system config network see network configuration system config network cmd 161 185 187 system config printer see printer configuration system config selinux see Security Level 414 Configuration Tool system config time see Time and Date Properties Tool system config users see user configuration and group configuration system logviewer see Log Viewer system switch mail see Mail Transport Agent Switcher system switch mail nox see Mail Transport Agent Switcher T TCP wrappers 206 telinit 206 telnet 213 tftp 57 time configuration 305 synchronize with NTP server 307 time zone configuration 308 timetool see Time and Date Properties Tool token ring connection see network configuration top 379 tune2fs converting to ext3 with 76 reverting to ext2 with 77 U user configuration adding users 320 adding users to groups 322 changing full name 322 changing home directory 322 changing login shell 322 changing password 322 command line configuration 324 passwd 324 useradd 324 filtering list of users 319 locking user accounts 322 modify groups for a user 321 modifying users 321 password forcing expiration of 326 password expiration 322 setting user account expiration 322 viewing list of users 319 User Manager see user configuration user private groups see groups and shared directories 334 useradd command user account creation using
353. or example you may need to shrink a partition with resize2fs which does not yet support ext3 In this situation it may be necessary to temporarily revert a file system to ext2 To revert a partition you must first unmount the partition by logging in as root and typing umount dev mapper VolGroup00 LogVol02 Next change the file system type to ext2 by typing the following command as root sbin tune2fs O has_journal dev mapper VolGroup00 LogVol02 Check the partition for errors by typing the following command as root sbin e2fsck y dev mapper VolGroup00 LogVol02 Then mount the partition again as ext2 file system by typing mount t ext2 dev mapper VolGroup00 LogVol02 mount point In the above command replace mount point with the mount point of the partition Next remove the journal file at the root level of the partition by changing to the directory where it is mounted and typing wm i o yoursmed 77 Chapter 6 The ext3 File System You now have an ext2 partition If you want to permanently change the partition to ext2 remember to update the etc fstab file 78 Chapier 7 Logical Volume Manager LVM 1 What is LVM LVM is a method of allocating hard drive space into logical volumes that can be easily resized instead of partitions With LVM a hard drive or set of hard drives is allocated to one or more physical volumes A physical volume cannot span over more than one drive
354. or window The View menu item allows you to e View only active processes 380 System Processes e View all processes e View my processes e View process dependencies e Hide a process e View hidden processes e View memory maps e View the files opened by the selected process To stop a process select it and click End Process Alternatively you can also stop a process by selecting it clicking Edit on your menu and selecting Stop Process To sort the information by a specific column click on the name of the column This sorts the information by the selected column in ascending order Click on the name of the column again to toggle the sort between ascending and descending order File Edit View Help Process Listing Search View My Processes Se ProcessName v User Memory XServerMemory Nice ID Vv bash andriusb 4 9 MB 0 bytes 0 18245 A andriusb 5 3 MB 0 bytes 0 18279 v xinit andriusb 2 7 MB 0 bytes 0 18292 gnome session andriusb 20 3 MB 0 bytes 0 18322 bonobo activation server andriusb 8 3 MB 0 bytes 0 18358 clock applet andriusb 20 4 MB 0 bytes 0 18436 dbus daemon 1 andriusb 14 0 MB 0 bytes 0 18348 dbus launch andriusb 4 3 MB 0 bytes 0 18347 eggcups andriusb 39 9 MB 0 bytes 0 18410 gam_server andriusb 3 0 MB 0 bytes 0 18366 gconfd 2 andriusb 12 0 MB 0 bytes 0 18353 gnome keyring daemon andriusb 3 3 MB 0 bytes 0 18356 gnome keyring daemon andriusb 3 9MB 0 bytes 0 3434 E gnome panel a
355. ord home directory or login shell Account Info Select Enable account expiration if you want the account to expire on a certain date Enter the date in the provided fields Select Local password is locked to lock the user account and prevent the user from logging into the system Password Info Displays the date that the user s password last changed To force the user to change passwords after a certain number of days select Enable password expiration and enter a desired value in the Days before change required field The number of days before the user s password expires the number of days before the user is warned to change passwords and days before the account becomes inactive can also be changed Groups Allows you to view and configure the Primary Group of the user as well as other groups that you want the user to be a member of 1 3 Adding a New Group To add a new user group click the Add Group button A window similar to Figure 32 4 New 322 Modifying Group Properties Group appears Type the name of the new group to create To specify a group ID for the new group select Specify group ID manually and select the GID Note that Red Hat Enterprise Linux also reserves group IDs lower than 500 for system groups Group Name mygroup CI Specify group ID manually GID 500 Figure 32 4 New Group Click OK to create the group The new group appears in the group list 1 4 Modifying Group P
356. ords to shadow passwords and back to standard passwords 2 1 Command Line Configuration If you prefer command line tools or do not have the X Window System installed use this section to configure users and groups 2 2 Adding a User To add a user to the system 1 Issue the useradd command to create a locked user account useradd lt username gt 2 Unlock the account by issuing the passwd command to assign a password and set password 324 Adding a Group aging guidelines passwd lt username gt Command line options for useradd are detailed in Table 32 1 useradd Command Line Options Option Description c lt comment gt lt comment gt can be replaced with any string This option is generally used to specify the full name of a user d lt home dir gt Home directory to be used instead of default home lt username gt e lt date gt Date for the account to be disabled in the format YYYY MM DD f lt days gt Number of days after the password expires until the account is disabled If o is specified the account is disabled immediately after the password expires If 1 is specified the account is not be disabled after the password expires g lt group name gt Group name or group number for the user s default group The group must exist prior to being specified here G lt group list gt List of additional other than default group names or group numbers separated by commas of wh
357. ored at one time is determined by the number of counters for the processor However it is not a one to one correlation on some processors 390 Setting Events to Monitor certain events must be mapped to specific counters To determine the number of counters available execute the following command cat dev oprofile cpu_type The events available vary depending on the processor type To determine the events available for profiling execute the following command as root the list is specific to the system s processor type op_help The events for each counter can be configured via the command line or with a graphical interface For more information on the graphical interface refer to Section 8 Graphical Interface If the counter cannot be set to a specific event an error message is displayed To set the event for each configurable counter via the command line use opcont rol opcontrol vent lt event name gt lt sample rate gt Replace lt event name gt with the exact name of the event from op_help and replace lt sample rate gt with the number of events between samples 2 2 1 Sampling Rate By default a time based event set is selected It creates a sample every 100 000 clock cycles per processor If the timer interrupt is used the timer is set to whatever the jiffy rate is and is not user settable If the cpu_type is not timer each event can have a sampling rate set for it The sampling rate is the
358. ose which package groups to install There are also options available to resolve and ignore package dependencies automatically Currently Kickstart Configurator does not allow you to select individual packages To install individual packages modify the packages section of the kickstart file after you save it Refer to Section 5 Package Selection for details 10 Pre Installation Script 52 Post Installation Script File Help Basic Configuration Pre Installation Script Installation Method Warning An error in this script might cause your kickstart installation j to fail Do not include the pre command at the beginning Boot Loader Options Partition Information CI Use an interpreter Network Configuration Authentication Type your pre script below Firewall Configuration Display Configuration Package Selection Pre Installation Script Post Installation Script Figure 2 15 Pre Installation Script You can add commands to run on the system immediately after the kickstart file has been parsed and before the installation begins If you have configured the network in the kickstart file the network is enabled before this section is processed To include a pre installation script type it in the text area To specify a scripting language to use to execute the script select the Use an interpreter option and enter the interpreter in the text box beside it For example usr bin python2 2 can be s
359. ost settings the default setting is used For example you can define a Webmaster email address in the Main tab and not define individual email addresses for each virtual host The HTTP Configuration Tool includes a default virtual host as shown in Figure 24 8 Virtual Hosts 266 Adding and Editing a Virtual Host Virtual Hosts Performance Tuning Virtual Hosts A Default Virtual Host Default virtual host Figure 24 8 Virtual Hosts http httpd apache org docs 2 0 vhosts and the Apache HTTP Server documentation on your machine provide more information about virtual hosts 3 1 Adding and Editing a Virtual Host To add a virtual host click the Virtual Hosts tab and then click the Add button You can also edit a virtual host by selecting it and clicking the Edit button 3 1 1 General Options The General Options settings only apply to the virtual host that you are configuring Set the name of the virtual host in the Virtual Host Name text area This name is used by HTTP Configuration Tool to distinguish between virtual hosts Set the Document Root Directory value to the directory that contains the root document such as index html for the virtual host This option corresponds to the DocumentRoot http httpd apache org docs 2 0 mod core html documentroot directive within the lt VirtualHost gt http httpd apache org docs 2 0 mod core html virtualhost directive The default DocumentRoot S var www html
360. ot easy to expand the size of the partition Even if the partition is moved to another hard drive the original hard drive space has to be reallocated as a different partition or not used LVM support must be compiled into the kernel and the default Red Hat kernel is compiled with LVM support To learn how to configure LVM during the installation process refer to Chapter 8 LVM Configuration 2 What is LVM2 LVM version 2 or LVM2 is the default for Red Hat Enterprise Linux which uses the device mapper driver contained in the 2 6 kernel LVM2 which is almost completely compatible with the earlier LVM1 version can be upgraded from versions of Red Hat Enterprise Linux running the 2 4 kernel Although upgrading from LVM1 to LVM2 is usually seamless refer to Section 3 Additional Resources for further details on more complex requirements and upgrading scenarios 3 Additional Resources Use these sources to learn more about LVM 3 1 Installed Documentation 80 Useful Websites rpm qd 1vm This command shows all the documentation available from the 1vm package including man pages lvm help This command shows all LVM commands available 3 2 Useful Websites e http sourceware org vm2 LVM2 webpage which contains an overview link to the mailing lists and more http tldp org HOWTO LVM HOWTO LVM HOWTO from the Linux Documentation Project 81 82 Chapier 8 LVM C
361. ot set the User directive to J root Using root as the user creates large security holes for your Web server The parent httpd process first runs as root during normal operations but is then immediately handed off to the apache user The server must start as root because it needs to bind to a port below 1024 Ports below 1024 are reserved for system use so they can not be used by anyone but root Once the server has attached itself to its port however it hands the process off to the apache user before it accepts any connection requests The Group value corresponds to the Group http httpd apache org docs 2 0 mod mpm_common html group directive The Group directive is similar to the User directive Group sets the group under which the server answers requests The default group is also apache 271 Chapter 24 Apache HTTP Serve 5 Performance Tuning Click on the Performance Tuning tab to configure the maximum number of child server processes you want and to configure the Apache HTTP Server options for client connections The default settings for these options are appropriate for most situations Altering these settings may affect the overall performance of your Web server Main Virtual Hosts Performance Tuning Servers Max Number of Connections 150 Connections Connection Timeout 300 O Allow unlimited requests per connection Max requests per connection 100 Requests per Connection C Allow Persi
362. ould contain at least eight characters include numbers and or punctuation and it should not be a word in a dictionary Also remember that your passphrase is case sensitive Note You are required to remember and enter this passphrase every time you start your secure server If you forget this passphrase the key must be completely re generated Re type the passphrase to verify that it is correct Once you have typed it in correctly etc httpd conf ssl key server key the file containing your key is created 281 Chapter 25 Apache HTTP Secur Note that if you do not want to type in a passphrase every time you start your secure server you must use the following two commands instead of make genkey to create the key Use the following command to create your key usr bin openssl genrsa 1024 gt etc httpd conf ssl key server key Then use the following command to make sure the permissions are set correctly for the file chmod go rwx etc httpd conf ssl key server key After you use the above commands to create your key you do not need to use a passphrase to start your secure server Caution Disabling the passphrase feature for your secure server is a security risk It is not recommended that you disable the passphrase feature for secure server Problems associated with not using a passphrase are directly related to the security maintained on the host machine For example if an unscrupulous individual compro
363. p00 Logvol101 is the volume you want to extend 1 Disable swapping for the associated logical volume swapoff v dev VolGroup00 LogVol01 2 Resize the LVM2 logical volume by 256 MB lvu lvresize dev VolGroup00 LogVol01 L 256M 3 Format the new swap space mkswap dev VolGroup00 LogVol01 4 Enable the extended logical volume Swapon va 5 Test that the logical volume has been extended properly cat proc swaps free 2 2 Creating an LVM2 Logical Volume for Swap To add a swap volume group assuming dev VolGroup00 LogVo102 is the swap volume you want to add 1 Create the LVM2 logical volume of size 256 MB 110 Creating a Swap File lvm lvcreate VolGroup00 n LogVol02 L 256M 2 Format the new swap space mkswap dev VolGroup00 LogVol02 3 Add the following entry to the etc fstab file dev VolGroup00 LogVol02 swap swap defaults 0 0 4 Enable the extended logical volume Swapon va 5 Test that the logical volume has been extended properly cat proc swaps free 2 3 Creating a Swap File To add a swap file 1 Determine the size of the new swap file in megabytes and multiply by 1024 to determine the number of blocks For example the block size of a 64 MB swap file is 65536 2 At a shell prompt as root type the following command with count being equal to the desired block size dd if dev zero of swapfile bs 1024 count 65536 3 Setup the swap file
364. pecified for a Python script This option corresponds to using spr interpreter usr bin python2 2 in your kickstart file Caution Do not include the spre command It is added for you 53 Chapter 2 Kickstart Configurator 11 Post Installation Script File Help Basic Configuration Post Installation Script Installation Method Warning An error in this script might cause your kickstart installation to fail Do not include the post command at the beginning Boot Loader Options Partition Information C Run outside of the chroot environment Network Configuration O Use an interpreter Authentication Firewall Configuration Type your post script below Display Configuration Package Selection Pre Installation Script Post Installation Script Figure 2 16 Post Installation Script You can also add commands to execute on the system after the installation is completed If the network is properly configured in the kickstart file the network is enabled and the script can include commands to access resources on the network To include a post installation script type it in the text area Caution J J Do not include the post command It is added for you For example to change the message of the day for the newly installed system add the following command to the post section echo Hackers will be punished gt etc motd 54 Chroot Environment Tip More
365. plication was compiled with debugging symbols Refer to Section 5 3 Using opannotate for details opcontrol Configures what data is collected Refer to Section 2 Configuring OProfile for details opreport Retrieves profile data Refer to Section 5 1 Using opreport for details oprofiled Runs as a daemon to periodically write sample data to disk Table 40 1 OProfile Commands 2 Configuring OProfile Before OProfile can be run it must be configured At a minimum selecting to monitor the kernel or selecting not to monitor the kernel is required The following sections describe how to use the opcont rol utility to configure OProfile As the opcont rol commands are executed the setup options are saved to the root oprofile daemonrc file 2 1 Specifying the Kernel First configure whether OProfile should monitor the kernel This is the only configuration option that is required before starting OProfile All others are optional To monitor the kernel execute the following command as root opcontrol setup vmlinux usr lib debug lib modules uname r vmlinux 388 Setting Events to Monitor Note The debuginfo package must be installed which contains the uncompressed kernel in order to monitor the kernel To configure OProfile not to monitor the kernel execute the following command as root opcontrol setup no vmlinux This command also loads the oprofile
366. point appears in the password field of the etc gshadow file which locks the group All other fields are blank 5 A directory for user juan is created in the home directory This directory is owned by user juan and group juan However it has read write and execute privileges only for the user juan All other permissions are denied 6 The files within the etc skel directory which contain default user settings are copied into the new home juan directory At this point a locked account called juan exists on the system To activate it the administrator must next assign a password to the account using the passwd command and optionally set password aging guidelines 3 Standard Users Table 32 4 Standard Users lists the standard users configured in the etc passwd file by an Everything installation The groupid GID in this table is the primary group for the user See Section 4 Standard Groups for a listing of standard groups User UID ej B Home Directory Shell root 0 0 root bin bash bin 1 1 bin sbin nologin daemon 2 2 sbin sbin nologin adm 3 4 var adm sbin nologin Ip 4 7 var spool l1pd sbin nologin sync 5 0 sbin bin sync shutdown 6 0 sbin sbin shutdown halt 7 0 sbin sbin halt mail 8 12 var spool mail sbin nologin news 9 13 etc news uucp 10 14 var spool uucp sbin nologin operator 11 0 root sbin nologin games 12 100 usr gam
367. ponding lines in the source code The resulting files generated should have the samples for the lines at the left It also puts in a comment at the beginning of each function listing the total samples for the function For this utility to work the executable must be compiled with GCC s g option By default Red Hat Enterprise Linux packages are not compiled with this option The general syntax for opannotate is as follows opannotate search dirs lt src dir gt source lt executable gt The directory containing the source code and the executable to be analyzed must be specified Refer to the opannotate man page for a list of additional command line options 397 Chapter 40 OProfile 6 Understanding dev oprofile The dev oprofile directory contains the file system for OProfile Use the cat command to display the values of the virtual files in this file system For example the following command displays the type of processor OProfile detected cat dev oprofile cpu_type A directory exists in dev oprofile for each counter For example if there are 2 counters the directories dev oprofile 0 and dev oprofile 1 exist Each directory for a counter contains the following files count The interval between samples enabled If 0 the counter is off and no samples are collected for it if 1 the counter is on and samples are being collected for it event The event to monitor kernel If 0
368. port on a Single Executable Profiling through timer interrupt TIMER 0 o samples 259210 Yi 5 212 iovo ayaill inex 359 1 3504 jou 65 0 2445 Xorg 62 OW 2332 TENES so 4 4 0 56 0 2106 idlbe 2 5 4 80 Sa OW 1279 Idlogililo 2 0 80 0 400 7 19 0 0715 liloxte s 2 162 17 0 063 baski 8 0 0301 Ic 2 3 4 86 e 0 0301 iIogele xilil 2 0 80 0 400 513 6 0 0226 iIlloegelajece 2 0 80 0 400 7 5 0 0188 oprofiled A W W150 iilsyorlaceecl 2 3 4 80 A 0 0150 Iulogrk lt lil 2 0 so 0 400 13 S W 011S render sti 252 3 0011S cu i 0 0038 liberyorto 800 2 Ta 1 0 0056 Liopem lt 0 07T 1 0 0058 Iioremnneceid Eose 08 L 0 0038 Imoxil so 62 1 0 0038 libgthread 2 0 so 0 400 7 i 0 0038 Idbowinek 1 so 4 9 0 Each executable is listed on its own line The first column is the number of samples recorded for the executable The second column is the percentage of samples relative to the total number of samples The third column is the name of the executable Refer to the opreport man page for a list of available command line options such as the r option used to sort the output from the executable with the smallest number of samples to the one with the largest number of samples 5 2 Using opreport ON a Single Executable To retrieve more detailed profiled information about a specific executable use opreport opreport lt mode gt lt executable gt lt executable gt must be the full path to the executable to be analyzed
369. prise Linux uses a user private group UPG scheme which makes UNIX groups 333 Chapter 32 Users and Groups easier to manage A UPG is created whenever a new user is added to the system A UPG has the same name as the user for which it was created and that user is the only member of the UPG UPGs make it safe to set default permissions for a newly created file or directory allowing both the user and the group of that user to make modifications to the file or directory The setting which determines what permissions are applied to a newly created file or directory is called a umask and is configured in the etc bashrc file Traditionally on UNIX systems the umask IS set to 022 which allows only the user who created the file or directory to make modifications Under this scheme all other users including members of the creator s group are not allowed to make any modifications However under the UPG scheme this group protection is not necessary since every user has their own private group 5 1 Group Directories Many IT organizations like to create a group for each major project and then assign people to the group if they need to access that project s files Using this traditional scheme managing files has been difficult wnen someone creates a file it is associated with the primary group to which they belong When a single person works on multiple projects it is difficult to associate the right files with the right group
370. provide a service you should turn it off to minimize your exposure to possible bug exploits There are several different methods for managing access to system services Decide which method of management to use based on the service your system s configuration and your level of Linux expertise The easiest way to deny access to a service is to turn it off Both the services managed by xinetd and the services in the etc rc d init d hierarchy also known as SysV services can be configured to start or stop using three different applications e Services Configuration Tool a graphical application that displays a description of each service displays whether each service is started at boot time for runlevels 3 4 and 5 and allows services to be started stopped and restarted e ntsysv a text based application that allows you to configure which services are started at boot time for each runlevel Non xinetd services can not be started stopped or restarted using this program e chkconfig a command line utility that allows you to turn services on and off for the different runlevels Non xinetd services can not be started stopped or restarted using this utility You may find that these tools are easier to use than the alternatives editing the numerous symbolic links located in the directories below etc rc d by hand or editing the xinetd configuration files in etc xinetd d Another way to manage access to system services is
371. ps vgscan Search for all volume groups vgsplit Move physical volumes into a new volume group version Display software and driver version information Table 12 2 ivm commands 123 124 Chapter 13 Implementing Disk Quotas Disk space can be restricted by implementing disk quotas which alert a system administrator is alerted before a user consumes too much disk space or a partition becomes full Disk quotas can be configured for individual users as well as user groups This kind of flexibility makes it possible to give each user a small quota to handle personal files Such as email and reports while allowing the projects they work on to have more sizable quotas assuming the projects are given their own groups In addition quotas can be set not just to control the number of disk blocks consumed but to control the number of inodes data structures that contain information about files in UNIX file systems Because inodes are used to contain file related information this allows control over the number of files that can be created The quota RPM must be installed to implement disk quotas 1 Configuring Disk Quotas To implement disk quotas use the following steps 1 Enable quotas per file system by modifying the etc fstab file 2 Remount the file system s 3 Create the quota database files and generate the disk usage table 4 Assign quota policies Each of these steps is discussed in detail in
372. que name for the profile You are now modifying the new profile as indicated by the status bar at the bottom of the main window Click on an existing device already in the list and click the Copy button to copy the existing device to a logical network device If you use the New button a network alias is created which is incorrect To change the properties of the logical device select it from the list and click Edit For example the nickname can be changed to a more descriptive name such as eth0_office so that it can be recognized more easily In the list of devices there is a column of checkboxes labeled Profile For each profile you can check or uncheck devices Only the checked devices are included for the currently selected profile For example if you create a logical device named eth0_office in a profile called Office and want to activate the logical device if the profile is selected uncheck the etno device and check the eth0_office device For example Figure 17 16 Office Profile shows a profile called Office with the logical device eth0O_ office It is configured to activate the first Ethernet card using DHCP 182 Working with Profiles File Profile Help B New Edit Copy Delete 7 Activate Deactivate You may configure network devices associated with physical hardware here Multiple logical devices can be associated with a single piece of hardware Protest pevce Nwetname rvoe C active eth0 et
373. quota check proceeds e u Check user disk quota information e g Check group disk quota information After quotacheck has finished running the quota files corresponding to the enabled quotas user and or group are populated with data for each quota enabled locally mounted file system such as home 1 4 Assigning Quotas per User The last step is assigning the disk quotas with the edquota command To configure the quota for a user as root in a shell prompt execute the command edquota username Perform this step for each user who needs a quota For example if a quota is enabled in etc fstab for the home partition dev VolGroup00 LogVo102 and the command edquota testuser is executed the following is shown in the editor configured as the default for the system Disk quotas for user testuser uid 501 Filesystem blocks soft hard inodes soft hard dev VolGroup00 LogVol02 440436 0 0 37418 0 0 Note The text editor defined by the EDITOR environment variable is used by edquota To change the editor set the EDITOR environment variable in your bash_profile file to the full path of the editor of your choice 127 Chapier 13 Implementing Disk The first column is the name of the file system that has a quota enabled for it The second column shows how many blocks the user is currently using The next two columns are used to set soft and hard block limits for the user on the file system The inodes column shows
374. r a kickstart file if the ks command line argument is passed to the kernel CD ROM 1 and Diskette The linux ks floppy command also works if the ks cfg file is located on a vfat or ext2 file system on a diskette and you boot from the Red Hat Enterprise Linux CD ROM 1 An alternate boot command is to boot off the Red Hat Enterprise Linux CD ROM 1 and have the kickstart file on a vfat or ext2 file system on a diskette To do so enter the following command at the boot prompt linux ks hd fd0 ks cfg With Driver Disk If you need to use a driver disk with kickstart specify the dd option as well For example to 31 Chapter 1 Kickstart Installa boot off a boot diskette and use a driver disk enter the following command at the boot prompt linux ks floppy dd Boot CD ROM If the kickstart file is on a boot CD ROM as described in Section 8 1 Creating Kickstart Boot Media insert the CD ROM into the system boot the system and enter the following command at the boot prompt where ks cfg is the name of the kickstart file linux ks cdrom ks cfg Other options to start a kickstart installation are as follows ks nfs lt server gt lt path gt ks http lt server gt lt path gt ks floppy The installation program looks for the kickstart file on the NFS server lt server gt as file lt path gt The installation program uses DHCP to configure the Ethernet card For example if your NFS server is serv
375. r num Remove the partition select device Select a different device to configure set minor numflagstate Set the flag on a partition state is either on or off Table 12 1 partea Commands 1 1 Viewing the Partition Table After starting parted type the following command to view the partition table print A table similar to the following appears Disk geometry for dev sda Disk label type msdos Minor Start End Type i 0 031 101 975 primey 2 MOISIS 5098 754 primary 3 S093 V35 6361 677 primary 4 G36l ENT 8675 727 extended 5 0361 VOE TSS 895 illogical Disk geometry for dev hda 0 000 9765 Disk label type msdos Minor Sterr End Type il 0 031 MONO jowalmawy 2 LOL YS 611 850 primary 3 Gil soi 760 891 primary 4 160 891 9758 232 extended 5 160 922 9750n 2S2 logical 0 000 8678 789 megabytes Filesystem Flags ext3 boot ext3 linux swap ext3 492 megabytes Filesystem Flags ext3 boot linux swap ext3 lba ext3 116 Creating a Partition The first line displays the size of the disk the second line displays the disk label type and the remaining output shows the partition table In the partition table the Minor number is the partition number For example the partition with minor number 1 corresponds to dev sdal The Start and End values are in megabytes The Type is one of primary extended or logical The Filesystem is the file system type which can be o
376. r settings are not saved If you want to save your Apache HTTP Server configuration settings click the OK button in the bottom right corner of the HTTP Configuration Tool window A dialog window appears If you answer Yes your settings are saved in etc httpd conf httpd conf Remember that your original configuration file is overwritten with your new settings If this is the first time that you have used the HTTP Configuration Tool a dialog window appears warning you that the configuration file has been manually modified If the HTTP Configuration Tool detects that the httpd conf configuration file has been manually modified it saves the manually modified file as etc httpd conf httpd conf bak Important y as After saving your settings you must restart the httpd daemon with the command service httpd restart You must be logged in as root to execute this command 273 Chapter 24 Apache HTTP Serve 7 Additional Resources To learn more about the Apache HTTP Server refer to the following resources 7 1 Installed Documentation usr share docs httpd lt version gt migration html The Apache Migration HOWTO document contains a list of changes from version 1 3 to version 2 0 as well as information about how to migration the configuration file manually 7 2 Useful Websites http www apache org The Apache Software Foundation http httpd apache org docs 2 0 The Apache Software Foundation s documentat
377. r shells If you enable SMB you must make users accounts known to the workstation by enabling LDAP NIS or Hesiod or by using the usr sbin useradd command to make their accounts known to the workstation To use this option you must have the pam_smb package installed smbservers The name of the server s to use for SMB authentication To specify more than one server separate the names with commas smbworkgroup The name of the workgroup for the SMB servers Chapter 1 Kickstart Installa enablecache Enables the nscd service The nscd service caches information about users groups and various other types of information Caching is especially helpful if you choose to distribute information about users and groups over your network using NIS LDAP or hesiod boot loader required Specifies how the GRUB boot loader should be installed This option is required for both installations and upgrades For upgrades if GRUB is not the current boot loader the boot loader is changed to GRUB To preserve other boot loaders use boot loader upgrade append Specifies kernel parameters To specify multiple parameters separate them with spaces For example bootloader location mbr append hdd ide scsi ide nodma driveorder Specify which drive is first in the BIOS boot order For example bootloader driveorder sda hda location Specifies where the boot record is written Valid values
378. random key using the instructions provided in Section 6 Generating a Key Once you have a key make sure you are in the usr share ssl certs directory and type the following command make testcert 284 aCA The following output is shown and you are prompted for your passphrase unless you generated a key without a passphrase tmasik TH usr bin openssl req new key etc httpd conf ssl key server key x509 clays 565 Olin CluGl int ep cle Olli ssl ert server Git Using configuration from usr share ssl openssl cnf Enter pass phrase Next you are asked for more information The computer s output and a set of inputs looks like the following provide the correct information for your organization and host You are about to be asked to enter information that will be incorporated into your certificate request What you are about to enter is what is called a Distinguished Name or a DN There are quite a few fields but you can leave some blank For some fields there will be a default value If you enter the field will be left blank Country Nam 2 letter code GB US State or Province Name full name Berkshire North CarolinaLocality Name eg city Newbury RaleighOrganization Name eg company My Company Ltd My Company Inc Organizational Unit Name eg section DocumentationCommon Name your name or server s hostname myhost example comEmail Address myemail example com
379. ration by implementing multiple RAID devices On the Disk Partitioning Setup screen select Manually partition with Disk Druid 1 Creating the RAID Partitions In a typical situation the disk drives are new or are formatted Both drives are shown as raw devices with no partition configuration in Figure 10 1 Two Blank Drives Ready For Configuration 99 Chapter 10 Software RAID Con Disk Setup Choose where you would like Red Hat Enterprise Linux AS to be installed If you do not know how to partition your system or if you need help with using the manual partitioning tools refer to the product documentation If you used automatic partitioning you can either accept the current partition settings click Next or modify the setup using the manual partitioning tool If you are manually partitioning your system you can see your current hard drive s and partitions displayed below Use Hide Help Release Notes v Drive dev sda 8676 MB Model IBM PSG ST39103LC Free 8678 MB Drive dev sdb 8676 MB Model IBM PSG ST39204LC Free 8678 MB New Edit Reset RAID LVM 7 Mount Point Size Hard Drives V dev sda Free Free space 8679 1 1107 V dev sdb Free Free space 8679 1 1107 C Hide RAID device LVM Volume Group members Figure 10 1 Two Blank Drives Ready For Configuration 1 In Disk Druid choose RAID to enter the
380. rdware RAID level 5 is equal to the capacity of member disks minus the capacity of one member disk The storage capacity of Software RAID level 5 is equal to the capacity of the member partitions minus the size of one of the partitions if they are of equal size Linear RAID Linear RAID is a simple grouping of drives to create a larger virtual drive In linear RAID the chunks are allocated sequentially from one member drive going to the next drive only when the first is completely filled This grouping provides no performance benefit as it is unlikely that any I O operations will be split between member drives Linear RAID also offers no redundancy and in fact decreases reliability if any one member drive fails the 2 PANG ATavRE WOH USA GeddieeGaparity tit mtata aadhnaembenSuGKs in the array which wastes drive space For example if you have RAID level 1 set up so that your root partition exists on two 40G drives you have 80G total but are only able to access 40G of that 80G The other 40G acts like a mirror of the first 40G 3 Parity information is calculated based on the contents of the rest of the member disks in the array This information can then be used to reconstruct data when one disk in the array fails The reconstructed data can then be used to satisfy I O requests to the failed disk before it is replaced and to repopulate the failed disk after it has been replaced 4 RAID level 4 takes up the same amount of space as RAID le
381. re the NameVirtualHost http httpd apache org docs 2 0 mod core html namevirtualhost directive based on the host name of the server Specify the IP address in the IP address field To specify multiple IP addresses separate each IP address with spaces To specify a port use the syntax IP Address Port Use colon asterisk to configure all ports for the IP address Specify the host name for the virtual host in the Server Host Name field In the Aliases section click Add to add a host name alias Adding an alias here adds a ServerAlias http httpd apache org docs 2 0 mod core html serveralias directive within the NameVirtualHost http httpd apache org docs 2 0 mod core html namevirtualhost directive 3 1 2 SSL Note You cannot use name based virtual hosts with SSL because the SSL handshake when the browser accepts the secure Web server s certificate occurs before the HTTP request which identifies the appropriate name based virtual host If you plan to use name based virtual hosts remember that they only work with your non secure Web server 268 Adding and Editing a Virtual Host General Options Page Options SSL SSL Configuration Certificate File etc httpd conf ssl crt server crt Certificate Key File etc httpd conf ssl key server key Certificate Chain File etc httpd conf ssl crt ca crt Certificate Authority File etc httpd conf ssl crt ca bundle crt E SSL Options IC FakeBasic
382. red global parameters Global parameters apply to all the sections below it Important D Nags If the configuration file is changed the changes do not take effect until the DHCP daemon is restarted with the command service dhcpd restart Tip Instead of changing a DHCP configuration file and restarting the service each time using the omshe11 command provides an interactive way to connect to query and change the configuration of a DHCP server By using omshe11 all changes can be made while the server is running For more information on omshe11 refer to the omshe11 man page 246 Configuration File In Example 23 1 Subnet Declaration the routers subnet mask domain name domain name servers and time offset options are used for any host statements declared below it Additionally a subnet can be declared a subnet declaration must be included for every subnet in the network If it is not the DHCP server fails to start In this example there are global options for every DHCP client in the subnet and a range declared Clients are assigned an IP address within the range subnet oo loc 0 netmask 255 255 255 0 4 option routers 192 168 i ASAR option subnet mask 295 5285 o295 00R option domain name example com option domain name servers 192 168 i i1 option time offset 18000 Eastern Standard Time rangem LOZ LOS 1 10 192 168 1 100 2 Example 23 1 Subnet Declaration All subnets tha
383. rences gt Mouse and select Left handed mouse for the mouse orientation 313 314 Chapter 31 X Window System Configuration During installation the system s monitor video card and display settings are configured To change any of these settings after installation use the X Configuration Tool To start the X Configuration Tool go to System on the panel gt Administration gt Display or type the command system config display ata shell prompt for example in an XTerm or GNOME terminal If the X Window System is not running a small version of X is started to run the program After changing any of the settings log out of the graphical desktop and log back in to enable the changes 1 Display Settings The Settings tab allows users to change the resolution and color depth The display of a monitor consists of tiny dots called pixels The number of pixels displayed at one time is called the resolution For example the resolution 1024x768 means that 1024 horizontal pixels and 768 vertical pixels are used The higher the resolution values the more images the monitor can display at one time The color depth of the display determines how many possible colors are displayed A higher color depth means more contrast between colors 315 Chapter 31 X Window System C Resolution 1024x768 Color Depth Millions of Colors Ja Figure 31 1 Display Settings 2 Display Hardware Se
384. rise Linux Installation Guide for instructions on creating boot media however before making the file iso image file copy the ks cfg kickstart file to the isolinux directory To perform a pen based flash memory kickstart installation the kickstart file must be named ks cfg and must be located in the flash memory s top level directory Create the boot image first and then copy the ks cfg file For example the following transfers a boot image to the pen drive dev sda using the dd 29 Chapter 1 Kickstart Installa command dd if diskboot img of dev sda bs 1M Note Creation of USB flash memory pen drives for booting is possible but is heavily dependent on system hardware BIOS settings Refer to your hardware manufacturer to see if your system supports booting to alternate devices 8 2 Making the Kickstart File Available on the Network Network installations using kickstart are quite common because system administrators can easily automate the installation on many networked computers quickly and painlessly In general the approach most commonly used is for the administrator to have both a BOOTP DHCP server and an NFS server on the local network The BOOTP DHCP server is used to give the client system its networking information while the actual files used during the installation are served by the NFS server Often these two servers run on the same physical machine but they are not required to To perform a ne
385. roperties To view the properties of an existing group select the group from the group list and click Properties from the menu or choose File gt Properties from the pulldown menu A window similar to Figure 32 5 Group Properties appears Group Data Group Users Group Name mygroup 323 Chapter 32 Users and Groups Figure 32 5 Group Properties The Group Users tab displays which users are members of the group Use this tab to add or remove users from the group Click OK to save your changes 2 User and Group Management Tools Managing users and groups can be a tedious task this is why Red Hat Enterprise Linux provides tools and conventions to make them easier to manage The easiest way to manage users and groups is through the graphical application User Manager system config users For more information on User Manager refer to Section 1 User and Group Configuration The following command line tools can also be used to manage users and groups useradd usermod and userdel1 Industry standard methods of adding deleting and modifying user accounts groupadd groupmod and groupde1 Industry standard methods of adding deleting and modifying user groups gpasswd Industry standard method of administering the etc group file pwck grpck Tools used for the verification of the password group and associated shadow files pwconv pwunconv Tools used for the conversion of passw
386. router level rather than the application level content like proxy firewalls Processes packets at the protocol layer but cannot filter packets at an application layer Complex network architectures can make establishing packet 189 Chapter 18 Firewalls Method Description Linux kernel has built in packet filtering functionality through the Netfilter kernel subsystem Advantages Since packets are not transmitted through a proxy network performance is faster due to direct connection from client to remote host Disadvantages filtering rules difficult especially if coupled with IP masquerading or local subnets and DMZ networks Proxy Proxy firewalls filter all requests of a certain protocol or type from LAN clients to a proxy machine which then makes those requests to the Internet on behalf of the local client A proxy machine acts as a buffer between malicious remote users and the internal network client machines Gives administrators control over what applications and protocols function outside of the LAN Some proxy servers can cache frequently accessed data locally rather than having to use the Internet connection to request it This helps to reduce bandwidth consumption Proxy services can be logged and monitored closely allowing tighter control over resource utilization on the network Proxies are often application specific HTTP Telnet etc
387. rting in text mode 375 Mail User Agent 375 Master Boot Record 67 reinstalling 70 MD5 passwords 292 memory usage 382 mkfs 118 mkpart 118 modem connection see network configuration modprobe 372 modprobe conf 371 monitor settings for dual head 317 settings for X 316 mounting NFS file systems 221 MTA setting default 375 switching with Mail Transport Agent Switcher 375 MUA 375 N NAT see Network Address Translation neat see network configuration Netfilter 190 additional resources 203 Netfilter 6 203 Network Address Translation 198 with iptables 198 Network Administration Tool see network configuration Network Booting Tool 57 pxeboot 61 pxeos 59 using with diskless environments 64 using with PXE installations 57 network configuration device aliases 185 DHCP 163 Ethernet connection 163 activating 165 ISDN connection 166 activating 167 logical network devices 181 managing etc hosts 180 managing DNS Settings 178 managing hosts 180 modem connection 168 activating 170 overview 162 PPPoE connection 170 profiles 181 activating 184 restoring from file 187 saving to file 187 static IP 163 token ring connection 172 activating 175 wireless connection 175 activating 178 xDSL connection 170 activating 172 Network Device Control 184 Network File System see NFS Network Time Protocol see NTP NFS etc fstab 221 additional resources 229 autofs se
388. rtition asprimary C Make partition on specific drive ondisk Drive for example hda or sde C Use existing partition onpart Partition for example hdal or sdc3 Format partition Figure 2 5 Creating Partitions To edit an existing partition select the partition from the list and click the Edit button The same Partition Options window appears as when you chose to add a partition as shown in Figure 2 5 Creating Partitions except it reflects the values for the selected partition Modify the partition options and click OK To delete an existing partition select the partition from the list and click the Delete button 4 1 1 Creating Software RAID Partitions To create a software RAID partition use the following steps 42 Creating Partitions 1 Click the RAID button 2 Select Create a software RAID partition 3 Configure the partitions as previously described except select Software RAID as the file system type Also you must specify a hard drive on which to make the partition or specify an existing partition to use Mount Point File System Type software RAID Size MB 2048 Additional Size Options Fixed size Oi Grow to maximum of MB O Fill all unused space on disk CO Use recommended swap size C Force to be a primary partition asprimary Make partition on specific drive ondisk Drive sdal for example hda or sdc Use ing partition onpart Partition for example
389. s use the x option and do not specify any permissions setfacl x lt rules gt lt files gt For example to remove all permissions from the user with UID 500 setfacl x u 500 project somefile 3 Setting Default ACLs To set a default ACL add a before the rule and specify a directory instead of a file name For example to set the default ACL for the share directory to read and execute for users not in the user group an access ACL for an individual file can override it setfacl m d o rx share 4 Retrieving ACLs To determine the existing ACLs for a file or directory use the get facl command getfacl lt filename gt It returns output similar to the following file file owner andrius group andrius user rw user smoore r CGieowjos se MASTS 8 8 eS relaeies 3 bE If a directory is specified and it has a default ACL the default ACL is also displayed such as file file owner andrius group andrius 135 Chapter 14 Access Control Lists WS Ce S EWS USSC SMNONOMETS 3 eS Goras s e mas kii ha GLNSE K S default user rwx default user andrius rwx default group r x default mask rwx default other r x 5 Archiving File Systems With ACLs Warning d The tar and dump commands do not backup ACLs The star utility is similar to the tar utility in that it can be used to generate archives of files however some of its options are different Ref
390. s are normally blank If a soft limit has been exceeded the column contains a time specification equal to the amount of time remaining on the grace period If the grace period has expired none appears in its place 2 3 Keeping Quotas Accurate Whenever a file system is not unmounted cleanly due to a system crash for example it is necessary to run quotacheck However quotacheck can be run on a regular basis even if the system has not crashed Running the following command periodically keeps the quotas more accurate the options used have been described in Section 1 1 Enabling Quotas quotacheck avug The easiest way to run it periodically is to use cron As root either use the crontab e command to schedule a periodic quotacheck or place a script that runs quotacheck in any one 130 Additional Resources of the following directories using whichever interval best matches your needs e etc cron hourly e etc cron daily e etc cron weekly e etc cron monthly The most accurate quota statistics can be obtained when the file system s analyzed are not in active use Thus the cron task should be schedule during a time where the file system s are used the least If this time is various for different file systems with quotas run quot acheck for each file system at different times with multiple cron tasks Refer to Chapter 34 Automated Tasks for more information about configuring cron 3 Additional Resources
391. s if this is selected e Server The Samba server tries to verify the username and password combination by passing them to another Samba server If it can not the server tries to verify using the user authentication mode Specify the NetBIOS name of the other Samba server in the Authentication Server field e Share Samba users do not have to enter a username and password combination on a per Samba server basis They are not prompted for a username and password until they try to connect to a specific shared directory from a Samba server e User Default Samba users must provide a valid username and password on a per Samba server basis Select this option if you want the Windows Username option to work Refer to Section 2 1 2 Managing Samba Users for details Encrypt Passwords This option must be enabled if the clients are connecting from a system with Windows 98 Windows NT 4 0 with Service Pack 3 or other more recent versions of Microsoft Windows The passwords are transfered between the server and the client in an encrypted format instead of as a plain text word that can be intercepted This corresponds to the encrypted passwords option Refer to Section 2 3 Encrypted Passwords for more information about encrypted Samba passwords Guest Account When users or guest users log into a Samba server they must be mapped to a valid user on the server Select one of the existing usernames on the system to be the guest
392. scription and Location to distinguish this printer from others that you may configure on your system Click Forward to proceed In the window shown in Figure 33 4 Adding an IPP Printer enter the hostname of the IPP printer in the Hostname field as well as a unique name for the printer in the Printername field Queue type Select a queue type Networked CUPS IPP Path servername example com printers queuel Figure 33 4 Adding an IPP Printer Click Forward to continue Next select the printer type Refer to Section 5 Selecting the Printer Model and Finishing for details 3 Adding a Samba SMB Printer You can add a Samba SMB based printer share by clicking the New Printer button in the main Printer Configuration Tool window to display the window in Figure 33 2 Adding a Printer Enter a unique name for the printer in the Printer Name field The printer name can contain letters numbers dashes and underscores _ it must not contain any spaces You can also use the Description and Location fields to further distinguish this printer from others that may be configured on your system Both of these fields are optional and may contain spaces 340 Adding a Samba SMB Printer Queue type Select a queue type Networked Windows SMB Figure 33 5 Adding a SMB Printer As shown in Figure 33 5 Adding a SMB Printer available SMB shares are auto
393. scsessavcnesdedercbevsancceeheperctasnecdewstspardbaeeenceevbensresaseacdeasdes 349 Tes GROWN eeeeeveshny ici banca Tene EA E E sadneneshliy E A a E aE 349 1 1 Configuring Cron Tasks ceccceeeceeeeeeeeeeeeeeeeeaeaaeeeeeeeeeeeeaeaaeeees 349 1 2 Controlling Access to Cron ssssssssssssssesssssrrrreresssrrrrrrrnerssrsrrnne 351 1 3 Starting and Stopping the Service ceeeeeeeseeeeeeeeeeeeeeaeeaeeees 351 2 Aland Baten eiaeia N Rete ancy die EA 351 2 1 Configuring At JODS srrarciinenianii da a i aiaa 352 2 2 Configuring Batch Jobs sssssessesssrssssesssrsrrerrnssssrrrrrrrnesesrernnne 353 2 3 Viewing Pending JODS saaeesssseerreeesrrrrnerrnrnsnnnnnennrnnnnnrnnennennna 353 2 4 Additional Command Line Options 0 ccccceeeeeeeeeeeeeeeeeeeeeaes 353 2 5 Controlling Access to At and Batch 0 cceceeeeeeeeeeeeeeeeeeeeaes 353 2 6 Starting and Stopping the Service ceceeeeeeeeeeeeeeeeeeeeeeeeeaes 354 3 Additional RESOUrCES ceceeececeeeee cece teen cece aa eeeeeeaaeeeeeeaaeeeeseaeeeeseaaees 354 3 1 Installed Documentation 0 2 eee cee ee ee naaier a i 354 S0 Log PICS sereen EA 355 1 Locating Log FES eusrcnirreneieen inecek E ENNEA EROR E 355 2 VIGWING Log FIOS eeo a a S 355 SeACGING a LOG FIE sere he ddawdesd caneteediegetecd denen disadaneeatceuvtcabaniatess 357 4 Examining Log Files sisirin aA 358 36 Manually Upgrading the Kernel ce cececeeeeeeeeeeeee
394. scue mode and reconfigure the boot loader Another common problem occurs when using a partitioning tool to resize a partition or create a new partition from free space after installation and it changes the order of your partitions If the partition number of your partition changes the boot loader might not be able to find it to mount the partition To fix this problem boot in rescue mode and modify the boot grub grub conf file For instructions on how to reinstall the GRUB boot loader from a rescue environment refer to Section 2 1 Reinstalling the Boot Loader 1 2 Hardware Software Problems This category includes a wide variety of different situations Two examples include failing hard drives and specifying an invalid root device or kernel in the boot loader configuration file If either of these occur you might not be able to reboot into Red Hat Enterprise Linux However if you boot into one of the system recovery modes you might be able to resolve the problem or at least get copies of your most important files 1 3 Root Password 67 Chapter 5 Basic System Recovery What can you do if you forget your root password To reset it to a different password boot into rescue mode or single user mode and use the passwd command to reset the root password 2 Booting into Rescue Mode Rescue mode provides the ability to boot a small Red Hat Enterprise Linux environment entirely from CD ROM or some other boot method i
395. see parted diskless environment 63 adding hosts 65 Network Booting Tool 64 NFS configuration 64 overview 63 display settings for X 315 DMZ see Demilitarized Zone documentation finding installed 152 DSA keys generating 217 DSOs loading 276 du 384 Dynamic Host Configuration Protocol see DHCP E e2fsck 77 e2label 119 emergency mode 71 Ethernet connection see network configuration exim 375 expiration of password forcing 326 exporting NFS file Systems 224 exports 226 ext2 reverting from ext3 77 ext3 406 converting from ext2 76 creating 76 features 75 F feedback xviii file systems 383 ext2 see ext2 ext3 see ext3 LVM see LVM NFS see NFS findsmb 241 firewall configuration see Security Level Configuration Tool firewall types 189 network address translation NAT 189 packet filter 189 proxy 189 firewalls 189 additional resources 203 and connection tracking 202 and malicious software 201 policies 196 stateful 202 types 189 Firewalls iptables 190 floppy group use of 303 free 382 ftp 213 G getfacl 135 GNOME System Monitor 380 gnome system monitor 380 GnuPG checking RPM package signatures 150 group configuration adding groups 322 filtering list of groups 319 groupadd 325 modify users in groups 324 modifying group properties 323 viewing list of groups 319 groups see group configuration additional resources 335 installed doc
396. senee eeen Kinra Na REN 153 53 Related BOOKS sretno naa T TS 153 16 Red Hat Network sessa O ES 155 IV Network Related Configuration ccccceeeeeeeeeaeeeeeeeeeeeeeeeaeaaeaeeeeeeeeeeaeaaaaneeeeeees 159 17 Network Configuration scscisccccssivecccseenecnasntivecceasnevscent dancaewenseeeal teoeeasaeeeenente 161 T QOVOIVIOW cnihirisscicaces tiny ena yeideacstativ AE a E E EEA a E 162 2 Establishing an Ethernet Connection c ccceceeeeeeeeeeeeeeeeeeeeeeeaeeaeeees 163 3 Establishing an ISDN Connection cccceeeeeeeeeeee ee eeeeeeeeeeeeeeeeaeaaeeees 166 4 Establishing a Modem Connection cceeeeeeeeeeeeeeeeeeeeeeeeeeeeeaeaaeeees 168 5 Establishing an xDSL Connection ccee eee eeeeeeeeeeeeeeeeeeaeeteeeeeeeeeeeeaes 170 6 Establishing a Token Ring Connection ccceeeeeeeeeeeeeeeeeeeeeeeeeeeaes 172 7 Establishing a Wireless Connection ccceccceeeeeeeeeeeeeeeeaaeeeeeeeeeeeeeeaea 175 8 Managing DNS Settings cccccceeeeeeeeeee cess ee aeeeeeeeeeeeeeaeaaaaeeneeeeeeeeeaaa 178 9 Managing Hosta scc fceseedetecerves iinei erea veteedvens cocks TENSEI EAEEREN RNE E 180 10 Working with Profiles 2 00 0 eee cece cette cere nate eeeeaaeeeeeeaaeeeeeeaaeeeeeeaaaeees 181 11 Device AllaS S merai eevee ives ete r TR ee eden vata 185 12 Saving and Restoring the Network Configuration s cseeeeeeeeees 187 18 Firewall sortien e EAEE EEE AA R 189 1 Netikter
397. serijjciom gt o lt NFS RUSS D 0 S Cilieme exenjole coim L lt net location gt k lt kernel gt K lt kickstart gt lt os identifer gt The following list explains the options e a Specifies that an OS instance is being added to the PXE configuration e i lt description gt Replace lt description gt with a description of the OS instance This corresponds to the Description field in Figure 3 1 Network Installation Setup p lt NFS HTTP FTP gt Specify which of the NFS FTP or HTTP protocols to use for installation Only one may be specified This corresponds to the Select protocol for installation menu in Figure 3 1 Network Installation Setup D lt 0 1 gt Specify o which indicates that it is nota diskless configuration since pxeos can be used to configure a diskless environment as well e sclient example com Provide the name of the NFS FTP or HTTP server after the s option This corresponds to the Server field in Figure 3 1 Network Installation Setup L lt net locat ion gt Provide the location of the installation tree on that server after the L option This corresponds to the Location field in Figure 3 1 Network Installation Setup e k lt kernel gt Provide the specific kernel version of the server installation tree for booting K lt kickstart gt Provide the location of the kickstart file if available 59 Chapter 3 PXE Network Inst
398. sername tohostname lt remotefile gt The lt localfile gt specifies the source including path to the file such as var log maillog The lt remotefile gt specifies the destination which can be a new filename such as tmp hostname maillog For the remote system if you do not have a preceding the path will be relative to the home directory of username typically nome username To transfer the local file snadowman to the home directory of your account on penguin example net type the following at a shell prompt replace username with your username scp shadowman username penguin example net shadowman This will transfer the local file shadowman to home username shadowman On penguin example net Alternately you can leave off the final shadowman in the scp command The general syntax to transfer a remote file to the local system is as follows scp username tohostname lt remotefile gt lt newlocalfile gt The lt remotefile gt specifies the source including path and lt newlocalfile gt specifies the destination including path Multiple files can be specified as the source files For example to transfer the contents of the directory downloads to an existing directory called uploads on the remote machine penguin example net type the following at a shell prompt scp downloads username penguin example net uploads 215 Chapter 20 OpenSSH 3 3 Using the ssep Command The sftp utility can be used to open
399. ses etc samba smb conf as its configuration file If you change this configuration file the changes do not take effect until you restart the Samba daemon with the command service smb restart 236 Encrypted Passwords To specify the Windows workgroup and a brief description of the Samba server edit the following lines in your smb conf file workgroup WORKGROUPNAME server string BRIEF COMMENT ABOUT SERVER Replace woRKGROUPNAME with the name of the Windows workgroup to which this machine should belong The BRIEF COMMENT ABOUT SERVER is optional and is used as the Windows comment about the Samba system To create a Samba share directory on your Linux system add the following section to your smb conf file after modifying it to reflect your needs and your system sharename comment Insert a comment here path home share valid users tfox carole public no writable yes printable no create mask 0765 The above example allows the users tfox and carole to read and write to the directory home share on the Samba server from a Samba client 2 3 Encrypted Passwords Encrypted passwords are enabled by default because it is more secure If encrypted passwords are not used plain text passwords are used which can be intercepted by someone using a network packet sniffer It is recommended that encrypted passwords be used The Microsoft SMB Protocol originally used plain text passwords However Windo
400. size Resize a logical volume lvs Display information about logical volumes lvscan List all logical volumes in all volume groups pvchange Change attributes of physical volume s pvcreate Initialize physical volume s for use by LVM pvdata Display the on disk metadata for physical volume s pvdisplay Display various attributes of physical volume s pvmove Move extents from one physical volume to another pvremove Remove LVM label s from physical volume s pvresize Resize a physical volume in use by a volume group pvs Display information about physical volumes pvscan List all physical volumes segtypes List available segment types vgcfgbackup Backup volume group configuration vgcfgrestore Restore volume group configuration vgchange Change volume group attributes vgck Check the consistency of a volume group vgconvert Change volume group metadata format vgcreate Create a volume group vgdisplay Display volume group information vgexport Unregister a volume group from the system vgextend Add physical volumes to a volume group vgimport Register exported volume group with system vgmerge Merge volume groups vgmknodes Create the special files for volume group 122 LVM Partition Management Command Description devices in dev vgreduce Remove a physical volume from a volume group vgremove Remove a volume group vgrename Rename a volume group vgs Display information about volume grou
401. so hard rules are not possible Each system s most used applications should be accounted for when determining swap size Important File systems and LVM2 volumes assigned as swap space cannot be in use when being modified For example no system processes can be assigned the swap space as well as no amount of swap should be allocated and used by the kernel Use the free and cat proc swaps commands to verify how much and where swap is in use The best way to achieve swap space modifications is to boot your system in rescue mode and then follow the instructions for each scenario in the remainder of this chapter Refer to Chapter 5 Basic System Recovery for instructions on booting into rescue mode When prompted to mount the file system select Skip 109 Chapter 11 Swap Space Sometimes it is necessary to add more swap space after installation For example you may upgrade the amount of RAM in your system from 128 MB to 256 MB but there is only 256 MB of swap space It might be advantageous to increase the amount of swap space to 512 MB if you perform memory intense operations or run applications that require a large amount of memory You have three options create a new swap partition create a new swap file or extend swap on an existing LVM2 logical volume It is recommended that you extend an existing logical volume 2 1 Extending Swap on an LVM2 Logical Volume To extend an LVM2 swap logical volume assuming dev VolGrou
402. so that they do not start at boot time The selected mail daemon is started and any other mail daemon is stopped thus making the changes take place immediately For more information about email protocols and MTAs refer to the Red Hat Enterprise Linux Reference Guide 376 Part VI System Monitoring System administrators also monitor system performance Red Hat Enterprise Linux contains tools to assist administrators with these tasks Chapter 39 Gathering System Information Before you learn how to configure your system you should learn how to gather essential system information For example you should know how to find the amount of free memory the amount of available hard drive space how your hard drive is partitioned and what processes are running This chapter discusses how to retrieve this type of information from your Red Hat Enterprise Linux system using simple commands and a few simple programs 1 System Processes The ps ax command displays a list of current system processes including processes owned by other users To display the owner alongside each process use the ps aux command This list is a static list in other words it is a Snapshot of what was running when you invoked the command If you want a constantly updated list of running processes use top as described below The ps output can be long To prevent it from scrolling off the screen you can pipe it through less ps aux less You can
403. ss of 10 10 0 1 would be 10 10 0 1 kickstart Note that if you do not specify a server name then the client system attempts to use the server that answered the BOOTP DHCP request as its NFS server If you do not specify a path or file name the client system tries to mount kickstart from the BOOTP DHCP server and tries to find the kickstart file using the same lt ip addr gt kickstart file name as described above 9 Making the Installation Tree Available The kickstart installation must access an installation tree An installation tree is a copy of the binary Red Hat Enterprise Linux CD ROMs with the same directory structure If you are performing a CD based installation insert the Red Hat Enterprise Linux CD ROM 1 into the computer before starting the kickstart installation If you are performing a hard drive installation make sure the ISO images of the binary Red Hat Enterprise Linux CD ROMs are on a hard drive in the computer If you are performing a network based NFS FTP or HTTP installation you must make the installation tree available over the network Refer to the Preparing for a Network Installation section of the Red Hat Enterprise Linux Installation Guide for details 10 Starting a Kickstart Installation To begin a kickstart installation you must boot the system from boot media you have made or the Red Hat Enterprise Linux CD ROM 1 and enter a special boot command at the boot prompt The installation program looks fo
404. ssigning Quotas per File System cccceeeeeeseeeeeeeeeeeeeaeaaeeees 129 2 Managing Disk Quotas ceeeeeeeeeeeeee cece aa eeeeeeeeeeeeeeaaaaeeeeseeeeeeaeaaeaees 129 2 1 Enabling and Disabling 2 0 2 0 cece eeceeeeeee ee eeeeeeaaeeeeeeaaeeeeeeaaeeees 129 2 2 Reporting on Disk Quotas ccceeeee ee eeeeeeeeeeeeeeeeaneaeeeeeeeeeeeeaaa 130 2 3 Keeping Quotas Accurate eceeeeeeeeeeeeeeeeeeeeeeeeeaeaaeeeeeeeeeeeeaaa 130 3 Additional RESOUrCES ceceec cece eeee cece ence cece eeeeee ease EEEE AAEE 131 3 1 Installed Documentation 0 eeeeee cece ee eeeeeeaaeeeeeeaaeeeeeeaaaeees 131 3 2 Related BOOKS sestien an EE RRE 131 14 Access Control Lists 2 0 0 0 ccceceeeee cece ee ee eeee cree ee ee ae aaaeeeeeeeeeeeeeaaaaaeneeeeeeeeeaaa 133 1 Mounting File Systems 00 cceceeeeeeeaeeeeeeeeeeeeeeeaeaaeeteeeeeeeeeaeaaaaneeeeeees 133 teh NES orar saavetaneeamncces savecaes E E E see 133 2 Setting Access ACLS mirsi niaan anaana aniani 134 3 Setting Default ACLS sssrinin aaan daa 135 4 Retrieving ACLS scivischevhelsGeeceets sh trocusteidevtas aAA ti EEA a Ei 135 5 Archiving File Systems With ACLs ccceeeeecceeeeeeeeeeeeeeeeaeeeeeeeeeeeeeeeaea 136 6 Compatibility with Older Systems cceeeececeeeeeeeeeeeeeeeeaeeeeeeeeeeeeeeeaes 137 7 Additional RESOUICES eceeeeeeeee rrii R EE EARE 137 7 1 Installed Documentation cc ccceeececeeeee cece eeeeeeeeeeeeesea
405. stem It is similar to the authconfig command which can be run after the install By default passwords are normally encrypted and are not shadowed enablemd5 Use md5 encryption for user passwords enablenis Turns on NIS support By default enablenis uses whatever domain it finds on the network A domain should almost always be set by hand with the nisdomain option nisdomain NIS domain name to use for NIS services Chapter 1 Kickstart Installa nisserver Server to use for NIS services broadcasts by default useshadow Or enableshadow Use shadow passwords enableldap Turns on LDAP support in etc nsswitch conf allowing your system to retrieve information about users UIDs home directories shells etc from an LDAP directory To use this option you must install the nss_ldap package You must also specify a server and a base DN distinguished name with l1dapserver and ldapbasedn enableldapauth Use LDAP as an authentication method This enables the pam_ldap module for authentication and changing passwords using an LDAP directory To use this option you must have the nss_ldap package installed You must also specify a server and a base DN with ldapserver and ldapbasedn ldapserver If you specified either enableldap Or enableldapauth use this option to specify the name of the LDAP server to use This option is set in the etc ldap conf file
406. stent Connections Timeout for next Connection 15 Figure 24 11 Performance Tuning Set Max Number of Connections to the maximum number of simultaneous client requests that the server can handle For each connection a child httpd process is created After this maximum number of processes is reached no one else can connect to the Web server until a child server process is freed You can not set this value to higher than 256 without recompiling This option corresponds to the MaxClients http httpd apache org docs 2 0 mod mpm_common html maxclients directive Connection Timeout defines in seconds the amount of time that your server waits for receipts and transmissions during communications Specifically Connection Timeout defines how long your server waits to receive a GET request how long it waits to receive TCP packets on a POST or PUT request and how long it waits between ACKs responding to TCP packets By default Connection Timeout is set to 300 seconds which is appropriate for most situations This option corresponds to the Timeout 272 Saving Your Settings http httpd apache org docs 2 0 mod core html timeout directive Set the Max requests per connection to the maximum number of requests allowed per persistent connection The default value is 100 which should be appropriate for most situations This option corresponds to the MaxRequest sPerChild http httpd apache org docs 2 0 mod mpm_common html maxrequestsp
407. symbolic links to be followed Includes Allow server side includes IncludesNOEXEC Allow server side includes but disable the exec and include commands in CGI scripts Indexes Display a formatted list of the directory s contents if no DirectoryIndex Such as index htm1 exists in the requested directory Multiview Support content negotiated multiviews this option is disabled by default SymLinkslfOwnerMatch Only follow symbolic links if the target file or directory has the same owner as the link To specify options for specific directories click the Add button beside the Directory list box A window as shown in Figure 24 7 Directory Settings appears Enter the directory to configure in the Directory text field at the bottom of the window Select the options in the right hand list and configure the order http httpd apache org docs 2 0 mod mod_access html order directive with the left hand side options The order directive controls the order in which allow and deny directives are evaluated In the Allow hosts from and Deny hosts from text field you can specify one of the following Allow all hosts Type a11 to allow access to all hosts e Partial domain name Allow all hosts whose names match or end with the specified string Full IP address Allow access to a specific IP address e A subnet Such as 192 168 1 0 255 255 255 0 e A network CIDR specification such as 10 3 0 0 16
408. t Cpe One roll Start Output similar to the following is displayed Using log file var lib oprofile oprofiled log Daemon started Profiler running The settings in root oprofile daemonrc are used The OProfile daemon oprofiled is started it periodically writes the sample data to the var lib oprofile samples directory The log file for the daemon is located at var lib oprofile oprofiled log To stop the profiler execute the following command as root opcontrol shutdown 4 Saving Data Sometimes it is useful to save samples at a specific time For example when profiling an executable it may be useful to gather different samples based on different input data sets If the number of events to be monitored exceeds the number of counters available for the processor multiple runs of OProfile can be used to collect data saving the sample data to different files each time To save the current set of sample files execute the following command replacing lt name gt with a unique descriptive name for the current session opcontrol save lt name gt The directory var lib oprofile samples name is created and the current sample files are 393 Chapter 40 OProfile copied to it 5 Analyzing the Data Periodically the OProfile daemon oprofiled collects the samples and writes them to the var lib oprofile samples directory Before reading the data make sure all data has been written to this directory b
409. t password again This module is included in the pam package To enable this feature the PAM configuration file in etc pam d must include the following lines auth sufficient lib security pam_timestamp so session optional lib security pam_timestamp so The first line that begins with auth should be after any other auth sufficient lines and the line that begins with session should be after any other session optional lines If an application configured to use pam_timestamp is successfully authenticated from the Main Menu Button on the Panel the q icon is displayed in the notification area of the panel if you are running the GNOME or KDE desktop environment After the authentication expires the 302 The floppy Group default is five minutes the icon disappears The user can select to forget the cached authentication by clicking on the icon and selecting the option to forget authentication 6 The floppy Group If for whatever reason console access is not appropriate for you and your non root users are required access to your system s diskette drive this can be done using the floppy group Add the user s to the floppy group using the tool of your choice For example the gpasswd command can be used to add user fred to the floppy group gpasswd a fred floppy Now user fred is able to access the system s diskette drive from the console 303 304 Chapter 28 Date and Time Configuration The T
410. t share the same physical network should be declared within a shared net work declaration as shown in Example 23 2 Shared network Declaration Parameters within the shared network but outside the enclosed subnet declarations are considered to be global parameters The name of the shared network should be a descriptive title for the network such as using the title test lab to describe all the subnets in a test lab environment shared network name option domain name test redhat com option domain name servers nsl redhat com ns2 redhat com option routers 192 16S 0 2549 more parameters for EXAMPLE shared network subnet 192 oe 1 0 netmask 255 755 252 0 4 parameters for subnet range 192 168 1 1 192 168 1254 2 subnet 192 168 2 0 netmask 255 255 252 0 4 parameters for subnet rangem LY2 168 2 i 192 168 2 254 247 Chapter 23 Dynamic Host Conf Example 23 2 Shared network Declaration As demonstrated in Example 23 3 Group Declaration the group declaration can be used to apply global parameters to a group of declarations For example shared networks subnets and hosts can be grouped group option routers option subnet mask option domain name option domain name servers option time offset host apex Ls 25 Wo option host name apex exampl Bie icom Il ADF 57239 2390 xample com hardware ethernet 00 A0 78 8E 192 168 5 i Ip 18000 Eastern Standar
411. t the system is using shadow passwords A UID greater than 499 is created Under Red Hat Enterprise Linux UIDs and GIDs below 500 are reserved for system use e A GID greater than 499 is created The optional GECOS information is left blank The home directory for juan is set to home juan e The default shell is set to bin bash 2 Anew line for juan is created in etc shadow The line has the following characteristics e It begins with the username juan e Two exclamation points appear in the password field of the etc shadow file which locks the account Note If an encrypted password is passed using the p flag it is placed in the etc shadow file on the new line for the user The password is set to never expire 3 A new line for a group named juan is created in etc group A group with the same name as a user is called a user private group For more information on user private groups refer to Section 1 1 Adding a New User The line created in etc group has the following characteristics e It begins with the group name juan An x appears in the password field indicating that the system is using shadow group passwords e The GID matches the one listed for user juan in etc passwd 4 Anew line for a group named juan is created in etc gshadow The line has the following characteristics e It begins with the group name juan 329 Chapter 32 Users and Groups e An exclamation
412. tables service only lf you deactivate the ip tables service remember to deactivate the IPv6 network also Never leave a network device active without the matching firewall To force iptables to start by default when the system is booted use the following command root myServer chkconfig level 345 iptables on This forces iptables to start whenever the system is booted into runlevel 3 4 or 5 3 1 IPTables Command Syntax The following sample iptables command illustrates the basic command syntax 195 Chapter 18 Firewalls root myServer iptables A lt chain gt j lt target gt The a option specifies that the rule be appended to lt chain gt Each chain is comprised of one or more rules and is therefore also known as a ruleset The three built in chains are INPUT OUTPUT and FORWARD These chains are permanent and cannot be deleted The chain specifies the point at which a packet is manipulated The j lt target gt option specifies the target of the rule i e what to do if the packet matches the rule Examples of built in targets are ACCEPT DROP and REJECT Refer to the iptables man page for more information on the available chains options and targets 3 2 Basic Firewall Policies Establishing basic firewall policies creates a foundation for building more detailed user defined rules Each iptables chain is comprised of a default policy and zero or more rules which work in concert wit
413. the following sections 1 1 Enabling Quotas As root using a text editor edit the etc fstab file Add the usrquota and or grpquota options to the file systems that require quotas dev VolGroup00 LogVol00 ext3 defaults i i LABEL boot boot ext3 defaults i 2 none dev pts devpts gid 5 mode 620 0 0 none dev shm tmpfs defaults 0 none proc LOE defaults a none sys sysfs defaults 0 0 dev VolGroup00 LogVol02 home ERES defaults usrquota grpquota 1 2 dev VolGroup00 LogVol01 swap swap defaults 0 0 125 Chapier 13 Implementing Disk In this example the home file system has both user and group quotas enabled Note The following examples assume that a separate home partition was created during the installation of Red Hat Enterprise Linux Although not ideal the root partition the installation default created partition can be used for setting quota policies in the etc fstab file 1 2 Remounting the File Systems After adding the usrquota and or grpquota options remount each file system whose fstab entry has been modified If the file system is not in use by any process use one of the following methods e Issue the umount command followed by the mount command to remount the file system e Issue the mount o remount home command to remount the file system If the file system is currently in use the easiest method for remounting the file system is to reboot the system 1 3 Creating th
414. the group quota has been set use the command 128 Assigning Quotas per File System quota g devel 1 6 Assigning Quotas per File System To assign quotas based on each file system enabled for quotas use the command edquota t Like the other edquota commands this one opens the current quotas for the file system in the text editor Grace period befor MEGS LING SOE limes ter wiserrs 3 Time units may be days hours minutes or seconds Filesystem Block grace period Inode grace period dev mapper VolGroup00 LogVol02 7days 7days Change the block grace period or inode grace period save the changes to the file and exit the text editor 2 Managing Disk Quotas If quotas are implemented they need some maintenance mostly in the form of watching to see if the quotas are exceeded and making sure the quotas are accurate Of course if users repeatedly exceeds their quotas or consistently reaches their soft limits a system administrator has a few choices to make depending on what type of users they are and how much disk space impacts their work The administrator can either help the user determine how to use less disk space or increase the user s disk quota if needed 2 1 Enabling and Disabling It is possible to disable quotas without setting them to be 0 To turn all user and group quotas off use the following command quotaoff vaug If neither the u or g options are specified only the user quotas are disabl
415. thout the administrator having to change file permissions every time users write new files 6 Shadow Passwords In multiuser environments it is very important to use shadow passwords provided by the shadow ut ils package Doing so enhances the security of system authentication files For this reason the installation program enables shadow passwords by default The following lists the advantages pf shadow passwords have over the traditional way of storing passwords on UNIX based systems e Improves system security by moving encrypted password hashes from the world readable etc passwa file to etc shadow which is readable only by the root user e Stores information about password aging e Allows the use the etc login defs file to enforce security policies Most utilities provided by the shadow utils package work properly whether or not shadow passwords are enabled However since password aging information is stored exclusively in the etc shadow file any commands which create or modify password aging information do not work The following is a list of commands which do not work without first enabling shadow passwords chage gpasswd e usr sbin usermod e Or f options e usr sbin useradd e Or f options 7 Additional Resources For more information about users and groups and tools to manage them refer to the following resources 7 1 Installed Documentation 335 Chapter 32 Users and Groups e Related m
416. ting the LVM Logical Volumes n errereen 91 9 Redundant Array of Independent Disks RAID ccceeeeeeeeeeeeeeeeeaeeeeeeeeeees 95 Te What s RAID cacieresstvetiasaa a E E AE EAE E AE E a 95 2 Who Should Use RAID 0 0 2 c ccceceeeeeee ce eeeeeeeeeeeeeeeeaaeaeeeeeeeeeeaeaaaaeeneeeees 95 3 Hardware RAID versus Software RAID 0 cceceeeeeeeeeeeeeeeeeeeeeaaeneeneeeees 95 31 Hardware RAID serseri an E E 95 3 2 Software RAID ariora niina aaa iiaea 96 4 RAID Levels and Linear Support ssssssssssssssssrrisssssrsrrrrrrssssrrrrnreresssnes 96 10 Software RAID Configuration 200 00 cccceceeeeeeeee cece ee ee eeeeeeeeeeeeaeaaeeeeeeeeeeeeaeaaeaaes 99 1 Creating the RAID Partitions 0 0 0 0 cccccece ee ceeeeeee sees ae eeeeeeeeeeeeeeseaanneneeeees 99 2 Creating the RAID Devices and Mount Points n 103 vi Tis SWAP Space sieaas aiya eiss hiv bestia sies bev eee E EE E aa 109 1 What is Swap Space 0 0 ccc ceceee cece eee ceeeeeeeeeee esse aaeeneeeeeeeeeaeaaeaneeeeeees 109 2 AddINg SWAP Spate ou eee cece eee ceeceeeeeeeeee a ai 109 2 1 Extending Swap on an LVM2 Logical Volume 110 2 2 Creating an LVM2 Logical Volume for Swap eseeeeeeeee ees 110 2 3 Creating a Swap File aranean oiiaaie aaa ana aaa 111 3 Removing Swap Space 0 cccccceceeceeeeeeeceaa ee eeteeeeeeeeeaaaaaaeeeeeeeeeeaeaaaaaes 112 3 1 Reducing Swap on an LVM2 Logical Volume 112
417. tion or type the command system config authentication ata shell prompt for example in an XTerm or a GNOME terminal To start the text based version type the command authconfig as root at a shell prompt Important D Nee After exiting the authentication program the changes made take effect immediately 1 User Information The User Information tab has several options To enable an option click the empty checkbox beside it To disable an option click the checkbox beside it to clear the checkbox Click OK to exit the program and apply the changes 289 Chapter 26 Authentication Co User Information Authentication NIS Hesiod NIS is the Network Information Service It is Hesiod allows a system administrator to publish commonly used on small to medium networks user and group information in DNS It is v Eniabies MIS Support Configure NIS sometimes used in very large networks Enable Hesiod Support Configure Hesiod LDAP The Lightweight Directory Access Protocol is a Winbind standard way of searching a directory which can hold Winbind allows a system to retrieve information about users arbitrary data in a structured hierarchy LDAP is and to authenticate users by using information stored in an increasingly being used in small to large networks NTDOM or ADS server It is used in small to large networks Enable LDAP Support Co
418. tion such as name server the IP address or hostname of the t ftp server which provides the files necessary to start the installation program and the location of the files on the tftp server This is possible because of PXELINUX which is part of the syslinux package The following steps must be performed to prepare for a PXE installation 1 Configure the network NFS FTP HTTP server to export the installation tree 2 Configure the files on the tftp server necessary for PXE booting 3 Configure which hosts are allowed to boot from the PXE configuration 4 Start the t ftp service 5 Configure DHCP 6 Boot the client and start the installation 1 Setting up the Network Server First configure an NFS FTP or HTTP server to export the entire installation tree for the version and variant of Red Hat Enterprise Linux to be installed Refer to the section Preparing for a Network Installation in the Red Hat Enterprise Linux Installation Guide for detailed instructions 2 PXE Boot Configuration The next step is to copy the files necessary to start the installation to the t ftp server so they can be found when the client requests them The t ftp server is usually the same server as the network server exporting the installation tree To copy these files run the Network Booting Tool on the NFS FTP or HTTP server A separate PXE server is not necessary For the command line version of these instructions refer to Section 2 1 C
419. tions is port 443 The standard port for non secure Web communications is port 80 The secure server default configuration listens on both of the two standard ports Therefore do not need to specify the port number in a URL the port number is assumed However if you configure your server to listen on a non standard port for example anything other than 80 or 443 you must specify the port number in every URL which is intended to connect to the server on the non standard port For example you may have configured your server so that you have a virtual host running non secured on port 12331 Any URLs intended to connect to that virtual host must specify the port number in the URL The following URL example attempts to connect to a non secure server listening on port 12331 http server example com 12331 11 Additional Resources 286 Useful Websites Refer to Section 7 Additional Resources for more information about the Apache HTTP Server 11 1 Useful Websites http www redhat com mailman listinfo redhat secure server The redhat secure server mailing list You can also subscribe to the redhat secure server mailing list by emailing lt redhat secure server request redhat com gt and include the word subscribe in the subject line http www modssl org The mod_ss1 website is the definitive source for information about mod_ssl The website includes a wealth of documentation including a User Manual
420. tition cannot reside on an LVM volume group because the GRUB boot loader cannot read it 1 Select New 2 Select boot from the Mount Point pulldown menu 3 Select ext3 from the File System Type pulldown menu 4 Select only the sda checkbox from the Allowable Drives area 5 Leave 100 the default in the Size MB menu 6 Leave the Fixed size the default radio button selected in the Additional Size Options area 7 Select Force to be a primary partition to make the partition be a primary partition A primary partition is one of the first four partitions on the hard drive If unselected the partition is created as a logical partition If other operating systems are already on the system unselecting this option should be considered For more information on primary versus logical extended partitions refer to the appendix section of the Red Hat Enterprise Linux Installation Guide Refer to Figure 8 3 Creation of the Boot Partition to verify your inputted values 86 Creating the boot Partition Add Partition Mount Pot et SSC sda 8676 MB IBM PSG ST39103LC Allowable Drives C sdb 8676 MB IBM PSG ST39204LC Size MB 100 B Additional Size Options Fixed size O Fil al space up to MB oO p Fill to maximum allowable size Figure 8 3 Creation of the Boot Partition Click OK to return to the main screen The following figure displays the boot partition correctly set 87 C
421. to dhcpd leases The DHCP daemon could be killed or the system could crash after the lease database has been renamed to the backup file but before the new file has been written If this happens the dhcpd leases file does not exist but it is required to start the service Do not create a new lease file If you do all old leases are lost which causes many problems The correct solution is to rename the dhcpd 1leases backup file to dhcpd leases and then start the daemon 2 3 Starting and Stopping the Server A Important When the DHCP server is started for the first time it fails unless the dhcpd leases file exists Use the command touch var 1lib dhcp dhcpd leases to create the file if it does not exist If the same server is also running BIND as a DNS server this step is not necessary as starting the named service automatically checks for a dhcpd leases file To start the DHCP service use the command sbin service dhcpd start To stop the DHCP server use the command sbin service dhcpd stop By default the DHCP service does not start at boot time To configure the daemon to start automatically at boot time refer to Chapter 19 Controlling Access to Services for information on how to manage services If more than one network interface is attached to the system but the DHCP server should only be started on one of the interfaces configure the DHCP server to start only on that device In etc sysconfig dhcpd add the name
422. to rotate every week and keep four weeks worth of previous log files 2 Viewing Log Files Most log files are in plain text format You can view them with any text editor such as vi or Emacs Some log files are readable by all users on the system however root privileges are required to read most log files To view system log files in an interactive real time application use the Log Viewer To start the application go to Applications the main menu on the panel gt System Tools gt System Logs or type the command system logviewer at a shell prompt The application only displays log files that exist thus the list might differ from the one shown in Figure 35 1 Log Viewer To filter the contents of the log file for keywords type the keyword s in the Filter for text field and click Filter Click Reset to reset the contents 355 Chapter 35 Log Files File Edit Help Boot Log RPM Packages eran Lag This log file contains a list of RPM packages installed on Kernel Startup Log H the system This list is updated daily by an automated cron Mail Log task MySQL Server Log 4Suite 1 0 3 i386 rpm News Log Canna 3 7p3 7 EL4 i386 rpm RPM Pack Canna devel 3 7p3 7 EL4 i386 rpm Bide Canna libs 3 7p3 7 EL4 i386 rpm Security Log ElectricFence 2 2 2 19 i386 rpm System Log FreeWnn 1 10pl020 5 i386 rpm Update Agent Log FreeWnn devel 1 10pl020 5 i386 rpm FreeWnn libs 1 10pl020 5 i386 rpm GConf2 2 8 1 1 1386 rpm GConf2 d
423. to start profiling kernel mode for the counter again opcontrol vent lt event name gt lt sample rate gt lt unit mask gt 1 To configure OProfile not to count events in user mode for a specific counter execute the following command opcontrol vent lt event name gt lt sample rate gt lt unit mask gt lt kernel gt 0 Execute the following command to start profiling user mode for the counter again opcontrol vent lt event name gt lt sample rate gt lt unit mask gt lt kernel gt 1 When the OProfile daemon writes the profile data to sample files it can separate the kernel and library profile data into separate sample files To configure how the daemon writes to sample files execute the following command as root opcontrol separate lt choice gt lt choice gt can be one of the following none do not separate the profiles default library generate per application profiles for libraries 392 Starting and Stopping OProfile kernel generate per application profiles for the kernel and kernel modules all generate per application profiles for libraries and per application profiles for the kernel and kernel modules If separate library is used the sample file name includes the name of the executable as well as the name of the library 3 Starting and Stopping OProfile To start monitoring the system with OProfile execute the following command as roo
424. to the serverAdmin http httpd apache org docs 2 0 mod core html serveradmin directive in httpd conf If you configure the server s error pages to contain an email address this email address is used so that users can report a problem to the server s administrator The default value is root localhost Use the Available Addresses area to define the ports on which the server accepts incoming requests This option corresponds to the Listen http httpd apache org docs 2 0 mod mpm_common html listen directive in httpd conf By default Red Hat configures the Apache HTTP Server to listen to port 80 for non secure Web communications Click the Add button to define additional ports on which to accept requests A window as shown in Figure 24 2 Available Addresses appears Either choose the Listen to all addresses option to listen to all IP addresses on the defined port or specify a particular IP address over which the server accepts connections in the Address field Only specify one IP address per port number To specify more than one IP address with the same port number create an entry for each IP address If at all possible use an IP address instead of a domain name to prevent a DNS lookup failure Refer to htto httod apache org docs 2 0 dns caveats htm for more information about ssues Regarding DNS and Apache Entering an asterisk in the Address field is the same as choosing Listen to all addresses Clicking the Edit button in the Ava
425. to use DHCP The kickstart file is read from the bootServer from the DHCP response as if it is an NFS server sharing the kickstart file By default the bootServer is the same as the DHCP server The name of the kickstart file is one of the following e If DHCP is specified and the boot file begins with a the boot file provided by DHCP is looked for on the NFS server e If DHCP is specified and the boot file begins with something other then a the boot file provided by DHCP is looked for in the kickstart directory on the NFS server e If DHCP did not specify a boot file then the installation program tries to read the file kickstart 1 2 3 4 kickstart where 1 2 3 4 is the numeric IP address of the machine being installed ksdevice lt device gt The installation program uses this network device to connect to the network For example to start a kickstart installation with the kickstart file on an NFS server that is connected to the system through the eth1 device use the command ks nfs lt server gt lt path gt ksdevice eth1 at the boot prompt 33 34 Chapier 2 Kickstart Configurator Kickstart Configurator allows you to create or modify a kickstart file using a graphical user interface so that you do not have to remember the correct syntax of the file To use Kickstart Configurator you must be running the X Window System To start Kickstart Configurator select Applications the main menu on the panel
426. trolling Acces well as how to configure network access using them It also provides instructions for creating iptables firewall rules e Red Hat Enterprise Linux Security Guide Red Hat Inc This manual discusses securing services with TCP wrappers and xinetd such as logging denied connection attempts 212 Chapter 20 OpenSSH OpenSSH is a free open source implementation of the SSH S ecure SH ell protocols It replaces telnet ftp rlogin rsh and rcp with secure encrypted network connectivity tools OpenSSH supports versions 1 3 1 5 and 2 of the SSH protocol Since OpenSSH version 2 9 the default protocol is version 2 which uses RSA keys as the default 1 Why Use OpenSSH If you use OpenSSH tools you are enhancing the security of your machine All communications using OpenSSH tools including passwords are encrypted Telnet and ftp use plain text passwords and send all information unencrypted The information can be intercepted the passwords can be retrieved and your system could be compromised by an unauthorized person logging in to your system using one of the intercepted passwords The OpenSSH set of utilities should be used whenever possible to avoid these security problems Another reason to use OpenSSH is that it automatically forwards the p1spLay variable to the client machine In other words if you are running the X Window System on your local machine and you log in to a remote machine using the ss
427. tted over UDP Because of TCP s reliability only parts of that 8K data are transmitted at a time Error detection When a TCP connection breaks due to the server being unavailable the client stops sending data and restarts the connection process once the server becomes available With UDP since it s connection less the client continues to pound the network with data until the server reestablishes a connection The main disadvantage is that there is a very small performance hit due to the overhead associated with the TCP protocol 2 4 Preserving ACLs The Red Hat Enterprise Linux 5 0 0 kernel provides ACL support for the ext3 file system and ext3 file systems mounted with the NFS or Samba protocols Thus if an ext3 file system has ACLs enabled for it and is NFS exported and if the NFS client can read ACLs they are used by the NFS client as well For more information about mounting NFS file systems with ACLs refer to Chapter 14 Access Control Lists 3 Exporting NFS File Systems Sharing or serving files from an NFS server is known as exporting the directories The NFS Server Configuration Tool can be used to configure a system as an NFS server To use the NFS Server Configuration Tool you must be running the X Window System have root privileges and have the system config nfs RPM package installed To start the application select the Main Menu Button on the Panel gt System Settings gt Server Settings gt NFS or type t
428. ttings When the X Configuration Tool is started it probes the monitor and video card If the hardware is probed properly the information for it is shown on the Hardware tab as shown in Figure 31 2 Display Hardware Settings 316 Dual Head Display Settings Hardware Dual head FEl Monitor Type LCD Panel 1024x768 Video Card S3 Savage4 Ja Figure 31 2 Display Hardware Settings To change the monitor type or any of its settings click the corresponding Configure button To change the video card type or any of its settings click the Configure button beside its settings 3 Dual Head Display Settings If multiple video cards are installed on the system dual head monitor support is available and is configured via the Dual head tab as shown in Figure 31 3 Dual Head Display Settings 317 Chapter 31 X Window System C Settings Hardware Dual head Use dual head Second Monitor Type LCD Panel 1024x768 Second Video Card S3 Savage4 Resolution 1024x768 Color Depth Millions of Colors Desktop layout Spanning Desktops Figure 31 3 Dual Head Display Settings To enable use of Dual head check the Use dual head checkbox To configure the second monitor type click the corresponding Configure button You can also configure the other Dual head settings by using the corresponding drop down list For the Desktop layout option selecting Spanning Desktops allows both monitors to use a
429. tton to collect the physical volumes into volume groups A volume group is basically a collection of physical volumes You can have multiple logical volume groups but a physical volume can only be in one volume group Note There is overhead disk space reserved in the logical volume group The summation of the physical volumes may not equal the size of the volume group however the size of the logical volumes shown is correct 90 Creating the LVM Logical Volumes Make LVM Volume Group Volume Group Name Physical Extent 32 MB sda2 8512 00 MB Physical Volumes to Use sdbl 8640 00 MB Used Space 0 00 MB 0 0 Free Space 17152 00 MB 100 0 Total Space 17152 00 MB Logical Volumes Logical Volume Name Mount Point Size MB Figure 8 7 Creating an LVM Volume Group 2 Change the Volume Group Name if desired All logical volumes inside the volume group must be allocated in physical extent units By default the physical extent is set to 32 MB thus logical volume sizes must be divisible by 32 MBs If you enter a size that is not a unit of 32 MBs the installation program automatically selects the closest size in units of 32 MBs It is not recommended that you change this setting 4 Select which physical volumes to use for the volume group 2 4 Creating the LVM Logical Volumes Create logical volumes with mount points such as home and swap space Remember that boot cannot be a logical vol
430. twork based kickstart installation you must have a BOOTP DHCP server on your network and it must include configuration information for the machine on which you are attempting to install Red Hat Enterprise Linux The BOOTP DHCP server provides the client with its networking information as well as the location of the kickstart file If a kickstart file is specified by the BOOTP DHCP server the client system attempts an NFS mount of the file s path and copies the specified file to the client using it as the kickstart file The exact settings required vary depending on the BOOTP DHCP server you use Here is an example of a line from the dhcpd conf file for the DHCP server filename usr new machine kickstart next server blarg redhat com Note that you should replace the value after filename with the name of the kickstart file or the directory in which the kickstart file resides and the value after next server with the NFS server name If the file name returned by the BOOTP DHCP server ends with a slash then it is interpreted as a path only In this case the client system mounts that path using NFS and searches for a particular file The file name the client searches for is lt ip addr gt kickstart 30 Making the Installation Tree Available The lt ip addr gt section of the file name should be replaced with the client s IP address in dotted decimal notation For example the file name for a computer with an IP addre
431. twork was used to download and install the updated kernel follow the instructions in Section 5 Verifying the Initial RAM Disk Image and Section 6 Verifying the Boot Loader only do not change the kernel to boot by default Red Hat Network automatically changes the default kernel to the latest version To install the kernel manually continue to Section 4 364 Performing the Upgrade Performing the Upgrade 4 Performing the Upgrade After retrieving all of the necessary packages it is time to upgrade the existing kernel At a shell prompt as root change to the directory that contains the kernel RPM packages and follow these steps Important D es It is strongly recommended that the old kernel is kept in case there are problems with the new kernel Use the i argument with the rpm command to keep the old kernel Do not use the u option since it overwrites the currently installed kernel which creates boot loader problems Issue the following command the kernel version may vary rpm ivh kernel 2 6 9 5 EL lt arch gt rpm If the system is a multi processor system install the kernel smp packages as well the kernel version may vary rpm ivh kernel smp 2 6 9 5 EL lt arch gt rpm If the system is i686 based and contains more than 4 GB of RAM install the kerne1 hugemem package built for the i686 architecture as well the kernel version might vary rpm ivh kernel hugemem 2
432. u use to access your local Red Hat Enterprise Linux system If there are files shared on the Samba print server it is recommended that they also use a password different from what is used by the print queue 4 Adding a JetDirect Printer To add a JetDirect or AppSocket connected printer share click the New Printer button in the main Printer Configuration Tool window to display the window in Figure 33 2 Adding a Printer Enter a unique name for the printer in the Printer Name field The printer name can contain letters numbers dashes and underscores _ it must not contain any spaces You can also use the Description and Location fields to further distinguish this printer from others that may be configured on your system Both of these fields are optional and may contain spaces Queue type Select a queue type Networked JetDirect Printer Port printer example com 9100 Figure 33 6 Adding a JetDirect Printer Click Forward to continue Text fields for the following options appear 342 Selecting the Printer Model and Finishing e Hostname The hostname or IP address of the JetDirect printer e Port Number The port on the JetDirect printer that is listening for print jobs The default port is 9100 Next select the printer type Refer to Section 5 Selecting the Printer Model and Finishing for details 5 Selecting the Printer Model and Finishing Once you h
433. ub conf file as additional entries may be needed for GRUB to control additional operating systems e Reboot the system 3 Booting into Single User Mode One of the advantages of single user mode is that you do not need a boot CD ROM however it does not give you the option to mount the file systems as read only or not mount them at all If your system boots but does not allow you to log in when it has completed booting try single user mode In single user mode your computer boots to runlevel 1 Your local file systems are mounted but your network is not activated You have a usable system maintenance shell Unlike rescue mode single user mode automatically tries to mount your file system Do not use single user mode if your file system cannot be mounted successtully You cannot use single user mode if the runlevel 1 configuration on your system is corrupted On an x86 system using GRUB use the following steps to boot into single user mode 1 At the GRUB splash screen at boot time press any key to enter the GRUB interactive menu 2 Select Red Hat Enterprise Linux with the version of the kernel that you wish to boot and type a to append the line 3 Go to the end of the line and type single as a separate word press the Spacebar and then type single Press Enter to exit edit mode 4 Booting into Emergency Mode In emergency mode you are booted into the most minimal environment possible The root file system is mounted read
434. ume To add a logical volume click the Add button in the Logical Volumes section A dialog window as shown in Figure 8 8 Creating a Logical Volume 91 Chapter 8 LVM Configuration appears Make Logical Volume Mount Point lt Not Applicable gt File System Type swap Logical Volume Name LogVol02 Size MB 1024 Max size is 2112 MB Cancel P OK Figure 8 8 Creating a Logical Volume Repeat these steps for each volume group you want to create Tip You may want to leave some free space in the logical volume group so you can expand the logical volumes later The default automatic configuration does not do this but this manual configuration example does approximately 1 GB is left as free space for future expansion 92 Creating the LVM Logical Volumes Make LVM Volume Group Volume Group Name VolGroup00 sda2 8512 00 MB Physical Volumes to Use sdbl 8640 00 MB Used Space 16064 00 MB 93 7 Free Space 1088 00 MB 6 3 Total Space 17152 00 MB Logical Volumes LogVol00 10016 LogVol01 home 5024 LogVol02 N A 1024 Figure 8 9 Pending Logical Volumes Click OK to apply the volume group and all associated logical volumes The following figure shows the final manual configuration 93 Chapter 8 LVM Configuration New Edit Delete Reset RAID LVM Disk Setup TEIE Me ee ee Choose where you would like Lui Vduse Crou Red Hat Enterprise Linux AS to ps
435. umentation 335 floppy use of 303 GID 319 introducing 319 shared directories 334 standard 332 tools for management of groupadd 324 333 system config users 333 User Manager 324 user private 333 H hardware viewing 384 Hardware Browser 384 Hardware RAID see RAID hesiod 290 HTTP Configuration Tool directives see HTTP directives error log 260 modules 255 transfer log 260 HTTP directives DirectoryIndex 259 ErrorDocument 260 ErrorLog 261 Group 271 HostnameLookups 262 KeepAlive 273 KeepAliveTimeout 273 Listen 257 LogFormat 261 LogLevel 262 MaxClients 272 MaxKeepAliveRequests 273 Options 259 ServerAdmin 257 ServerName 256 TimeOut 272 TransferLog 261 User 271 httpd 255 hwbrowser 384 407 Index information about your system 379 insmod 373 installation kickstart see kickstart installations LVM 83 PXE see PXE installations software RAID 99 Internet connection see network configuration introduction xv ip6tables 203 iptables 190 194 additional resources 203 and DMZs 201 and malicious software 201 chains 196 FORWARD 198 INPUT 197 OUTPUT 197 POSTROUTING 200 PREROUTING 200 201 connection tracking 202 states 202 policies 196 rules 196 common 197 forwarding 198 NAT 200 201 restoring 196 saving 196 stateful inspection 202 states 202 using 195 ISDN connection see network configuration K Kerberos 291 kern
436. up00 LogVo102 is the LVM2 logical volume you want to mount If the partition is of type ext2 replace ext3 with ext2 69 Chapter 5 Basic System Recovery If you do not know the names of all physical partitions use the following command to list them feliei I If you do not know the names of all LVM2 physical volumes volume groups or logical volumes use the following commands to list them pvdisplay vgdisplay lvdisplay From the prompt you can run many useful commands such as ssh scp and ping if the network is started dump and restore for users with tape drives e parted and fdisk for managing partitions rpm for installing or upgrading software joe for editing configuration files Note If you try to start other popular editors such as emacs pico Or vi the joe editor is started 2 1 Reinstalling the Boot Loader In many cases the GRUB boot loader can mistakenly be deleted corrupted or replaced by other operating systems The following steps detail the process on how GRUB is reinstalled on the master boot record Boot the system from an installation boot medium e Type linux rescue at the installation boot prompt to enter the rescue environment 70 Booting into Single User Mode e Type chroot mnt sysimage to mount the root partition e Type sbin grub install dev hda to reinstall the GRUB boot loader where dev hda is the boot partition e Review the boot grub gr
437. ure a dynamic LVM file system or a traditional static ext2 ext3 file system For more information on configuring LVM on a RAID device select physical volume LVM and then refer to Chapter 8 LVM Configuration If LVM is not required continue on with the following instructions Select a device name such as mdO for the RAID device Choose your RAID level You can choose from RAID 0 RAID 1 and RAID 5 If you need assistance in determining which RAID level to implement refer to Chapter 9 Redundant Array of Independent Disks RAID 105 Chapter 10 Software RAID Con If you are making a RAID partition of boot you must choose RAID level 1 and it must use one of the first two drives IDE first SCSI second If you are not creating a seperate RAID partition of boot and you are making a RAID partition for the root file system it must be RAID level 1 and must use one of the first two drives IDE first SCSI second Error With Request Bootable partitions can only be on RAID1 devices Figure 10 7 The boot Mount Error 8 The RAID partitions created appear in the RAID Members list Select which of these partitions should be used to create the RAID device 9 If configuring RAID 1 or RAID 5 specify the number of spare partitions If a software RAID partition fails the spare is automatically used as a replacement For each spare you want to specify you must create an additional software RAID partition
438. us versions of the package installed Tip You don t want to use the u option for installing kernel packages because RPM replaces the previous kernel package This does not affect a running system but if the new kernel is unable to boot during your next restart there would be no other kernel to boot instead Using the i option adds the kernel to your GRUB boot menu etc grub conf Similarly removing an old unneeded kernel removes the kernel from GRUB Because RPM performs intelligent upgrading of packages with configuration files you may see a message like the following saving etc foo conf as etc foo conf rpmsave This message means that your changes to the configuration file may not be forward compatible with the new configuration file in the package so RPM saved your original file and installed a new one You should investigate the differences between the two configuration files and resolve them as soon as possible to ensure that your system continues to function properly Upgrading is really a combination of uninstalling and installing so during an RPM upgrade you can encounter uninstalling and installing errors plus one more If RPM thinks you are trying to 146 Freshening upgrade to a package with an older version number the output is similar to the following package foo 2 0 1 which is newer than foo 1 0 1 is already installed To force RPM to upgrade anyway use the oldpackage option Hom Uvin
439. use the ps command in combination with the grep command to see if a process is running For example to determine if Emacs is running use the following command ps ax grep emacs The top command displays currently running processes and important information about them including their memory and CPU usage The list is both real time and interactive An example of output from the top command is provided as follows top 15 02 46 ws 35 mim 4 users locc averages O 17 0 65 1 00 Tasis 110 total 1 running 107 sleeping 0 stopped 2 zombie Cpu s 41 1 us 2 05 Syp W 0S mi 56 6 ac 0 05 wa O 3 Int Q Oa si Nems 77 S0Z4R total 772028k used 2996k free 68468k buffers Swap 1048568k total 176k used 1048392k free 441172k cached PID USER PR NI VIRT RES SHR S CPU SMEM TIME COMMAND EA G ZAM coc tm om OM OH ODES mien 22 Garou Creer elo a Aa meo O 55564 33m 9784 S 13 5 4 4 0 25 96 gnome terminal 6475 mhideo 16 0 3612 968 160 R O 7 OW 000 LL too 4920 miniclee 15 0 20672 10m 73808 S 0 3 1 4 0301 61 wack ajyolee L root 16 1732 548 472 0 0 O 1 0 00 23 imit 2 roort 34 19 Q Q 0 0 0 0 0 00 00 ksortirae o 3 zoor 5 10 0 0 0 S 0 0 0 0 0 00 03 events 0 4 root 6 10 000 8 00 0 0 0 00 02 khalpsr 5 recor 5 10 0 0 0 0 0 0 0 0300 00 kagoicd 29 roor 5 10 0 0 O 0 0 0 0 0 00 00 kblocikey 0 47 woot 16000 0 S 00 00 Os01 74 pelklvusi 50 root 1L 10 0 0 0 S 0 0 0 0 0 00 00 aio 0 50 root 15 0 0 0 0 S 0 0 0 0 0 00 05 kmwsel 49 roct 16 0 0 0 S
440. user This option corresponds to all_squash e Specify local user ID for anonymous users If Treat all client users as anonymous users is selected this option lets you specify a user ID for the anonymous user This option corresponds to anonuid e Specify local group ID for anonymous users If Treat all client users as anonymous users is selected this option lets you specify a group ID for the anonymous user This option corresponds to anongid To edit an existing NFS share select the share from the list and click the Properties button To delete an existing NFS share select the share from the list and click the Delete button After clicking OK to add edit or delete an NFS share from the list the changes take place 226 Command Line Configuration immediately the server daemon is restarted and the old configuration file is saved as etc exports bak The new configuration is written to etc exports The NFS Server Configuration Tool reads and writes directly to the etc exports configuration file Thus the file can be modified manually after using the tool and the tool can be used after modifying the file manually provided the file was modified with correct syntax 3 1 Command Line Configuration If you prefer editing configuration files using a text editor or if you do not have the X Window System installed you can modify the configuration file directly The etc exports file controls what directories the N
441. utions for home and business markets Apart from the differences between hardware and software firewalls there are also differences in the way firewalls function that separate one solution from another Table 18 1 Firewall Types details three common types of firewalls and how they function Method Description Advantages Disadvantages NAT Network Address Translation NAT places Can be configured Cannot prevent malicious private IP subnetworks transparently to machines activity once users behind one or a small pool on a LAN connect to a service of public IP addresses Protection of many outside of the firewall masquerading all requests machines and services to one source rather than Pehind one or more several The Linux kernel external IP addresses has built in NAT simplifies administration functionality through the duties o Netfilter kernel subsystem Restriction of user access to and from the LAN can be configured by opening and closing ports on the NAT firewall gateway Packet A packet filtering firewall Filter reads each data packet Customizable through Cannot filter packets for that passes through a LAN It can read and process packets by header information and filters the packet based on sets of programmable rules implemented by the firewall administrator The the iptables front end utility Does not require any customization on the client side as all network activity is filtered at the
442. v md2 dev md0 dev md1 dev md2 ext3 swap ext3 software RAID software RAID software RAID software RAID software RAID software RAID y y 101 944 1027 6 7546 16 102 1028 7546 102 1028 7546 LVM 1 13 14 14 145 1106 1 B 14 144 145 1106 na Fy C Hide RAID device LVM Volume Group members The figure as shown in Figure 10 9 Final Sample RAID With LVM Configuration is an example of a RAID and LVM configuration 107 Chapter 10 Software RAID Con Disk Setup Choose where you would like Red Hat Enterprise Linux AS to be installed If you do not know how to partition your system or if you need help with using the manual partitioning tools refer to the product documentation If you used automatic partitioning you can either accept the current partition settings click Next or modify the setup using the manual partitioning tool If you are manually partitioning your system you can see your current hard drive s and partitions displayed below Use Hide Help Release Notes New Edit Delete Reset RAID LVM Mount Point T Size RAID Volume yes MB V LVM Volume Groups Y VolGroup00 LogVol02 LogVol01 LogVol00 RAID Devices dev md0 dev md1 V Hard Drives V dev sda dev sdal dev sda2 V dev sdb dev sdb1 dev sdb2 home boot VolGroup00 dev md0 dev md1 dev mdO dev md1 swap ext3 ext3
443. vel 5 but level 5 has more advantages For this reason level 4 is not supported 97 98 Chapter 10 Software RAID Configuration Software RAID can be configured during the graphical installation process the text based installation process or during a kickstart installation This chapter discusses how to configure software RAID during installation using the Disk Druid interface Read Chapter 9 Redundant Array of Independent Disks RAID first to learn about RAID the differences between hardware and software RAID and the differences between RAID 0 1 and 5 An overview of the steps required to configure RAID include e Applying software RAID partitions to the physical hard drives If you wish to have the boot partition boot reside on a RAID parition it must be on a RAID 1 partition Creating RAID devices from the software RAID partitions Optional Configuring LVM from the RAID devices Refer to Chapter 8 LVM Configuration for more information on configuring LVM after first configuring RAID Creating file systems from the RAID devices Note Although the following steps are illustrated during a GUI installation the same can be done during a text based installation Configuration of software RAID must be done manually in Disk Druid during the installation process Two 9 1 GB SCSI drives dev sda and dev sdb are used in the following examples They detail how to create a simple RAID 1 configu
444. with the command mkswap swapfile 4 To enable the swap file immediately but not automatically at boot time swapon swapfile 5 To enable it at boot time edit etc fstab to include the following entry 111 Chapter 11 Swap Space swapfile swap swap defaults 0 0 The next time the system boots it enables the new swap file 6 After adding the new swap file and enabling it verify it is enabled by viewing the output of the command cat proc swaps OF free 3 Removing Swap Space Sometimes it can be prudent to reduce swap space after installation For example say you downgraded the amount of RAM in your system from 1 GB to 512 MB but there is 2 GB of swap space still assigned It might be advantageous to reduce the amount of swap space to 1 GB since the larger 2 GB could be wasting disk space You have three options remove an entire LVM2 logical volume used for swap remove a swap file or reduce swap space on an existing LVM2 logical volume 3 1 Reducing Swap on an LVM2 Logical Volume To reduce an LVM2 swap logical volume assuming dev VolGroup00 LogVo101 is the volume you want to extend 1 Disable swapping for the associated logical volume swapoff v dev VolGroup00 LogVol01 2 Reduce the LVM2 logical volume by 512 MB lvm lvreduce dev VolGroup00 LogVol01 L 512M 3 Format the new swap space mkswap dev VolGroup00 LogVol01 4 Enable the extended logical volume Swapon va 5
445. wn non LVM partition In the following example it is the first partition on the first drive dev sda1 Bootable partitions cannot reside on LVM logical volumes e A single LVM volume group volGroup00 is created which spans all selected drives and all remaining space available In the following example the remainder of the first drive dev sda2 and the entire second drive dev sdb1 are allocated to the volume group 83 Chapter 8 LVM Configuration Two LVM logical volumes LogVo100 and Logvo101 are created from the newly created spanned volume group In the following example the recommended swap space is automatically calculated and assigned to Logvo101 and the remainder is allocated to the root file system LogVo100 Drive dev sda 8676 MB Model IBM PSG ST39103LC Disk Setup fe gt a Choose where you would like Drive dev sdb 8676 MB Model IBM PSG ST39204LC be installed New Edit Delete Reset RAID If you do not know how to need help with using the ume manual partitioning tools refer V LVM Volume Groups to the product documentation Y VolGroup00 17152 LogVol00 ext3 y 15872 If you used automatic LogVol01 ar 4 1280 partitioning you can either i Hard Dri accept the current partition avi Vv settings click Next or modify dev sda the setup using the manual dev sdal boot ext3 S 102 1 13 partitioning tool dev sda2 VolGroup00 LVM PV y 8574 14 1106
446. word to expire the first time a user logs in This forces users to change passwords the first time they log in Note This process will not work if the user logs in using the SSH protocol 1 Lock the user password If the user does not exist use the useradd command to create the user account but do not give it a password so that it remains locked If the password is already enabled lock it with the command usermod L usernam 2 Force immediate password expiration Type the following command chage d 0 username This command sets the value for the date the password was last changed to the epoch January 1 1970 This value forces immediate password expiration no matter what password aging policy if any is in place 3 Unlock the account There are two common approaches to this step The administrator can assign an initial password or assign a null password Warning d Do not use the passwa command to set the password as it disables the immediate password expiration just configured 327 Chapter 32 Users and Groups To assign an initial password use the following steps e Start the command line Python interpreter with the python command It displays the following Python 2 4 3 1 Jul 21 2006 08 46 09 GCC 4 1 1 20060718 Red Hat Ai il 9 m line s Vineilio eopyaesheiac Werechlics oe Vilieense itor more information gt gt gt At the prompt type the following
447. ws NT 4 0 with Service Pack 3 or higher Windows 98 Windows 2000 Windows ME and Windows XP require encrypted Samba passwords To use Samba between a Linux system and a system running one of these Windows operating systems you can either edit your Windows registry to use plaintext passwords or configure Samba on your Linux system to use encrypted passwords If you choose to modify your registry you must do so for all of your Windows machines this is risky and may cause further conflicts It is recommended that you use encrypted passwords for better security To configure Samba to use encrypted passwords follow these steps 1 Create a separate password file for Samba To create one based on your existing etc passwad file at a shell prompt type the following command 237 Chapter 22 Samba cat etc passwd mksmbpasswd sh gt etc samba smbpasswd If the system uses NIS type the following command ypcat passwd mksmbpasswd sh gt etc samba smbpasswd The mksmbpasswd sh script is installed in your usr bin directory with the samba package 2 Change the permissions of the Samba password file so that only root has read and write permissions chmod 600 etc samba smbpasswd 3 The script does not copy user passwords to the new file and a Samba user account is not active until a password is set for it For higher security it is recommended that the user s Samba password be different from the user s system password T
448. y executing the following command as root opcontrol dump Each sample file name is based on the name of the executable For example the samples for the default event on a Pentium Ill processor for bin bash becomes root bin bash dep root bin bash CPU_CLK_UNHALTED 100000 The following tools are available to profile the sample data once it has been collected opreport opannotate Use these tools along with the binaries profiled to generate reports that can be further analyzed Warning The executable being profiled must be used with these tools to analyze the data If it must change after the data is collected backup the executable used to create the samples as well as the sample files Samples for each executable are written to a single sample file Samples from each dynamically linked library are also written to a single sample file While OProfile is running if the executable being monitored changes and a sample file for the executable exists the existing sample file is automatically deleted Thus if the existing sample file is needed it must be backed up along with the executable used to create it before replacing the executable with a new version Refer to Section 4 Saving Data for details on how to backup the sample file 5 1 Using opreport The opreport tool provides an overview of all the executables being profiled The following is part of an example output 394 Using opre
449. y pair which is used by version 1 of the SSH Protocol If you are only connecting between systems that use DSA you do not need an RSA version 1 3 or RSA version 1 5 key pair 1 To generate an RSA for version 1 3 and 1 5 protocol key pair type the following command at a shell prompt ssh keygen t rsal Accept the default file location ssh identity Enter a passphrase different from your account password Confirm the passphrase by entering it again The public key is written to ssh identity pub The private key is written to ssh identity Do not give anyone the private key 2 Change the permissions of your ssh directory and your key with the commands chmod 755 sshand chmod 644 ssh identity pub 3 Copy the contents of ssh identity pub into the file ssh authorized_keys on the machine to which you wish to connect If the file ssh authorized_keys does not exist you can copy the file ssh identity pub to the file ssh authorized_keys onthe remote machine 4 If you are running GNOME skip to Section 3 4 4 Configuring ssh agent with GNOME If you are not running GNOME skip to Section 3 4 5 Configuring ssh agent 3 4 4 Configuring ssh agent with GNOME 218 Generating Key Pairs The ssh agent utility can be used to save your passphrase so that you do not have to enter it each time you initiate an ssh or scp connection If you are using GNOME the openssh askpass gnome package co
450. you to change paper type Options include Plain thick bond and transparency Resolution Configure the quality and detail of the printout default is 300 dots per inch dpi Toner Saving Choose whether the printer uses less toner to conserve resources 345 Chapter 33 Printer Configuration You can also configure printer job options using the Job Options tab Use the drop menu and choose the job options you wish to use such as Landscape modes horizontal or vertical printout copies or scaling increase or decrease the size of the printable area which can be used to fit an oversize print area onto a smaller physical sheet of print medium 8 Managing Print Jobs When you send a print job to the printer daemon such as printing a text file from Emacs or printing an image from The GIMP the print job is added to the print spool queue The print spool queue is a list of print jobs that have been sent to the printer and information about each print request such as the status of the request the the job number and more During the printing process the Printer Status icon appears in the Notification Area on the panel To check the status of a print job double click the Printer Status which displays a window similar to Figure 33 12 GNOME Print Status Figure 33 12 GNOME Print Status To cancel a specific print job listed in the GNOME Print Status select it from the list and select Edit gt Cancel Documents
451. ystem Tools gt Package Updater on your desktop e Execute the command yum from a shell prompt e Use the RHN website at hitps rhn redhat com e Click on the package icon when it appears in the panel to launch the Package Updater For more detailed instructions refer to the documentation available at http www redhat com docs manuals RHNetwork Tip Red Hat Enterprise Linux includes a convenient panel icon that displays visible alerts when there is an update for your Red Hat Enterprise Linux system This panel icon is not present if no updates are available 158 Part IV Network Related Configuration After explaining how to configure the network this part discusses topics related to networking such as how to allow remote logins share files and directories over the network and set up a Web server Chapter 17 Network Configuration To communicate with each other computers must have a network connection This is accomplished by having the operating system recognize an interface card such as Ethernet ISDN modem or token ring and configuring the interface to connect to the network The Network Administration Tool can be used to configure the following types of network interfaces e Ethernet e ISDN modem e xDSL e token ring e CIPE e wireless devices It can also be used to configure IPsec connections manage DNS settings and manage the etc hosts file used to store additional hostnames a
452. ystem and see what might be missing you could try the following command igo Va If some files are missing or appear to have been corrupted you should probably either re install the package or uninstall and then re install the package e At some point you might see a file that you do not recognize To find out which package owns it enter rpm qf usr bin ggv The output would look like the following Geir 2o 6 02 e We can combine the above two examples in the following scenario Say you are having problems with usr bin paste You would like to verify the package that owns that program but you do not know which package owns paste Enter the following command rpm Vf usr bin paste and the appropriate package is verified e Do you want to find out more information about a particular program You can try the following command to locate the documentation which came with the package that owns that 151 Chapter 15 Package Managemen program rpm qdf usr bin free The output would be similar to the following usr share doc procps 3 2 3 BUGS usr share doc procps 3 2 3 FAQ usr share doc procps 3 2 3 NEWS usr share doc procps 3 2 3 TODO usr share man manl free 1 gz usr share man manl pgrep 1 gz usr share man manl pkill 1l gz usr share man manl pmap 1 gz usr share man manl ps 1 gz usr share man manl skill 1l gz usr share man manl slabtop 1 gz usr share man manl snice 1 gz usr share man

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