Radio Shack FC-241 User's Manual
Contents
1. The important information in this example is contained in the first line GS Software and in the line that begins System image file The GS Software line shows the version of the operating system in the client router s RAM The System image file line show the filename of the system image loaded from the TFTP server Cisco 10S Configuration Fundamentals Configuration Guide Release 12 1 E Configuring Additional File Transfer Functions W Configuring a Router as a Server Configuring a Router as a RARP Server Reverse Address Resolution Protocol RARP is a protocol in the TCP IP stack that provides a method for finding IP addresses based on MAC physical addresses This functionality is the reverse of broadcasting Address Resolution Protocols ARPs through which a host can dynamically discover the MAC layer address corresponding to a particular IP network layer address RARP makes diskless booting of various systems possible for example diskless workstations that do not know their IP addresses when they boot such as Sun workstations or PCs on networks where the client and server are on separate subnets RARP relies on the presence of a RARP server with cached table entries of MAC layer to IP address mappings You can configure a Cisco router as a RARP server This feature enables the Cisco IOS software to answer RARP requests To configure the router as a RARP server use the follo2. Note For Cisco TTYs are commonly used in access servers The concept of TTY originated with UNIX For UNIX systems each physical device is represented in the file system Terminals are called TTY devices which stands for teletype the original UNIX terminal 3 The router host name For boot commands using rcp the software sends the router host name you cannot explicitly configure the remote username For the rcp copy request to execute successfully an account must be defined on the network server for the remote username If you are writing to the server the rcp server must be properly configured to accept the rcp write request from the user on the router For UNIX systems you must add an entry to the rhosts file for the remote user on the rcp server For example if the router contains the following configuration lines hostname Rtr1l ip rcemd remote username User0 and the router s IP address translates to Routerl company com then the rhosts file for User0 on the rcp server should contain the following line Routerl company com Rtr1 Refer to the documentation for your rcp server for more details Cisco 10S Configuration Fundamentals Configuration Guide Release 12 1 Configuring Additional File Transfer Functions Configuring a Router to Use FTP Connections Ml If the server has a directory structure the configuration file or image is written or copied relative to the directory associated with the remot
3. devices which include the address Disabling DNS Reverse Lookup for RCMD As a basic security check the Cisco IOS software does a reverse lookup of the client IP address using DNS This check is performed using a host authentication process When enabled the system records the address of the requesting client That address is mapped to a host name using DNS Then a DNS request is made for the IP address for that host name The IP address received is then checked against the original requesting address If the address does not match with any of the addresses received from DNS the RCMD request will not be serviced This reverse lookup is intended to help protect against spoofing However please note that the process only confirms that the IP address is a valid routable address it is still possible for a hacker to spoof the valid IP address of a known host Cisco 10S Configuration Fundamentals Configuration Guide Release 12 1 Configuring Additional File Transfer Functions Configuring a Router to Use rsh andrcp W This feature is enabled by default You can disable the DNS check for RCMD rsh and rcp access using the the following command in global configuration mode Command Purpose no ip rcemd domain lookup Disables Domain Name Service DNS lookup for rsh and rcp communications Configuring a Router to Use rsh You can use rsh to execute commands on remote systems to which you have access When you issue the
4. residing on a remote host or server on the network Cisco s implementation of rsh and rcp interoperates with the industry standard implementations amp Note Cisco uses the abbreviation RCMD Remote Command to indicate both rsh and rep The following tasks are covered in this section e Specifying the Source Interface for Outgoing RCMD Communications e Disabling DNS Reverse Lookup for RCMD e Configuring a Router to Use rsh e Configuring a Router to Use rcp Specifying the Source Interface for Outgoing RCMD Communications You can specify the source interface for RCMD rsh and rep communications For example the router can be configured so that RCMD connections use the loopback interface as the source address of all packets leaving the router To specify the interface associated with RCMP communications use the following command in global configuration mode Command Purpose ip remd source interface interface id Specifies the interface address that will be used to label all outgoing rsh and rcp traffic Specifying the source interface is most commonly used to specify a loopback interface This allows you to associate a permanent IP address with RCMD communications Having a permanent IP address is useful for session identification remote device can consistently idendify the origin of packets for the session A well known IP address can also be used for security purposes as you can then create access lists on remote
5. rsh commands on it after the router is enabled for rsh The user named netadmin4 is allowed to execute privileged EXEC mode commands on the router Both authentication database entries give the router s host name Router as the local username The last command enables the router for to support rsh commands issued by remote users Executing Commands Remotely Using rsh You can use rsh to execute commands remotely on network servers that support the remote shell protocol To use this command the rhosts files or equivalent files on the network server must include an entry that permits you to remotely execute commands on that host If the remote server has a directory structure as do UNIX systems the rsh command that you issue is remotely executed from the directory of the account for the remote user that you specify through the user username keyword and argument pair If you do not specify the user keyword and argument the Cisco IOS software sends a default remote username As the default value of the remote username the software sends the remote username associated with the current TTY process if that name is valid If the TTY remote username is invalid the software uses the router host name as the both the remote and local usernames To execute a command remotely on a network server using rsh use the following commands in user EXEC mode Command Purpose Step1 enable password Enters privileged EXEC mode Step2 rsh ip addr
6. Configuring Additional File Transfer Functions This chapter describes how to configure a router as a server change MOP parameters configure the router to forward extended BOOTP requests over asynchronous interfaces and configure rcp rsh and FTP For a complete description of the file transfer function commands mentioned in this chapter refer to the Additional File Transfer Functions Commands chapter in the Configuration Fundamentals Command Reference To locate documentation of other commands that appear in this chapter use the command reference master index or search online Additional Functions Task List To configure additional file transfer functions perform any of the tasks in the following sections e Configuring a Router as a Server e Specifying Asynchronous Interface Extended BOOTP Requests e Configuring a Router to Use rsh and rcp e Configuring a Router to Use FTP Connections Configuring a Router as a Server It is too costly and inefficient to have a machine which only acts as server on every network segment However when you do not have a server on every segment your network operations can incur enormous time delays across network segments You can configure a router to serve as a RARP or TFTP server to reduce costs and time delays in your network while allowing you to use your router for its regular functions Typically a router that is configured as a server provides other routers with operating system images fr
7. configure the router as an rsh server use the following commands in global configuration mode Command Purpose Step1 ip remd remote host local username ip address Creates an entry in the local authentication database host remote username enable level for each remote user who is allowed to execute rsh commands Step2 ip remd rsh enable Enables the software to support incoming rsh commands To disable the software from supporting incoming rsh commands use the no ip remd rsh enable command Cisco 10S Configuration Fundamentals Configuration Guide Release 12 1 E Configuring Additional File Transfer Functions HZ Configuring a Router to Use rsh and rep amp Note When support of incoming rsh commands is disabled you can still issue an rsh command to be executed on other routers that support the remote shell protocol and on UNIX hosts on the network The following example shows how to add two entries for remote users to the authentication database and enable a router to support rsh commands from remote users ip remd remote host Routerl 172 16 101 101 rmtnetad1l ip rcemd remote host Routerl 172 16 101 101 netadmin4 enable ip remd rsh enable The users named rmtnetad and netadmin4 are both on the remote host at IP address 172 16 101 101 Although both users are on the same remote host you must include a unique entry for each user Both users are allowed to connect to the router and remotely execute
8. copy running config startup config Saves the configuration file to your startup configuration reload Reloads the router to make your changes take effect Router reboots show version Verifies that the client router booted the correct image from the TFTP server A Caution Using the no boot system command as in the following example will invalidate all other boot system commands currently in the client router system configuration Before proceeding determine whether the system configuration stored in the client router should first be saved uploaded to a TFTP file server so you have a backup copy Configuring Additional File Transfer Functions A Caution Configuring a Router as a Server W The following example shows how to configure a router to use a TFTP server Client configure terminal Enter configuration commands one per line End with CTRL Z Client config no boot system Client config boot system gs7 k 9 17 172 31 111 111 Client config boot system rom Client config config register 0x010F Client config end Client copy running config startup config ok Client reload In this example the no boot system command invalidates all other boot system commands currently in the configuration memory and any boot system commands entered after this command will be executed first The second command boot system filename address tells the client router to look
9. e username on the server Use the ip remd remote username command to specify which directory on the server to use For example if the system image resides in the home directory of a user on the server you can specify that user s name as the remote username If you copy the configuration file to a personal computer used as a file server the computer must support rsh To override the default remote username sent on rcp requests use the following commands starting in privileged EXEC mode Command Purpose Step1 configure terminal Enters global configuration mode from the terminal Step 2 ip rcmd remote username username Specifies the remote username To remove the remote username and return to the default value use the no ip remd remote username command Configuring a Router to Use FTP Connections You configure a router to transfer files between systems on the network using the Internet File Transfer Protocol FTP With the Cisco IOS implementation of FTP you can set the following features e Passive mode FTP e User name e Password e IP address FTP Configuration Task List Use the instructions in the section Configuring FTP Connections to configure FTP on a router Configuring FTP Connections To configure FTP connections on a router use the following commands in global configuration mode Command Purpose ip ftp username string Specifies the user name to be used for the FTP connection ip ft
10. ess host user username Executes a command remotely using rsh remote command Cisco 10S Configuration Fundamentals Configuration Guide Release 12 1 Configuring Additional File Transfer Functions Configuring a Router to Use rsh andrcp W The following example executes the ls a command in the home directory of the user sharon on mysys cisco com using rsh Router enable Router rsh mysys cisco com user sharon ls a alias cshre emacs exrc history login mailrc newsrc oldnewsrc rhosts twmrc xsession jazz Router Configuring a Router to Use rcp The rcp copy commands rely on the rsh server or daemon on the remote system To copy files using rcp you do not need to create a server for file distribution as you do with TFTP You need only to have access to a server that supports the remote shell rsh Most UNIX systems support rsh Because you are copying a file from one place to another you must have read permission on the source file and write permission on the destination file If the destination file does not exist rcp creates it for you Although our rcp implementation emulates the functions of the UNIX rcp implementation copying files among systems on the network our command syntax differs from the UNIX rcp command syntax Our rcp support offers a set of copy commands that use rcp as the transport mechanism These rcp copy commands are similar in style to our TFTP copy comma
11. for the file gs7 k 9 17 on the TFTP server with an IP address of 172 31 111 111 Failing this the client router will boot from its system ROM in response to the boot system rom command which is included as a backup in case of a network problem The copy running config startup config command copies the configuration to the startup configuration and the reload command boots the system The system software gs7 k 9 17 in the example to be booted from the server 172 31 111 111 in the example must reside in Flash memory on the server If it is not in Flash memory the client router will boot the server s system ROM The following example shows sample output of the show version command after the router has rebooted Client gt show version GS Software GS7 Version 9 1 17 Copyright c 1986 1992 by cisco Systems Inc Compiled Wed 21 Oct 92 22 49 System Bootstrap Version 4 6 0 15 Current date and time is Thu 10 22 1992 13 15 03 Boot date and time is Thu 10 22 1992 13 06 55 env chassis uptime is 9 minutes System restarted by power on System image file is gs7 k 9 17 booted via tftp from 172 31 111 111 RP1 68040 processor with 16384K bytes of memory X 25 software Bridging software 1 Switch Processor 1 EIP controller 6 Ethernet 6 Ethernet IEEE 802 3 interface 128K bytes of non volatile configuration memory 4096K bytes of flash memory on embedded flash in RP1 Configuration register is 0x010F
12. multiple images end Exits configuration mode copy running config startup config Saves the configuration file to your startup configuration The TFTP session can sometimes fail TFTP generates the following special characters to help you determine why a TFTP session fails e An E character indicates that the TFTP server received an erroneous packet e An O character indicates that the TFTP server received an out of sequence packet e A period indicates a timeout For diagnosing any undue delay in the transfer the output is useful For troubleshooting procedures refer to the Internetwork Troubleshooting Guide publication In the following example the system can use TFTP to send copies of the Flash memory file version 10 3 in response to a TFTP Read Request for that file The requesting host is checked against access list 22 tftp server flash version 10 3 22 In the following example the system can use TFTP to send a copy of the ROM image gs3 k 101 in response to a TFTP Read Request for the gs3 k 101 file tftp server rom alias gs3 k 101 Cisco 10S Configuration Fundamentals Configuration Guide Release 12 1 Configuring Additional File Transfer Functions W Configuring a Router as a Server The following example a router to send a copy of the file gs7 k 9 17 in Flash memory in response to a TFTP Read Request The client router must reside on a network specified by access list 1 Thu
13. ncoming rcp requests is distinct from its ability to handle outgoing rcp requests The following example shows how to add two entries for remote users to the authentication database and then enable the software to support remote copy requests from remote users The users named netadminI on the remote host at IP address 172 16 15 55 and netadmin3 on the remote host at IP address 172 16 101 101 are both allowed to connect to the router and remotely execute rcp commands on it after the router is enabled to support rcp Both authentication database entries give the host name Router as the local username The last command enables the router to support for rcp requests from remote users ip remd remote host Routerl 172 16 15 55 netadminl ip rcemd remote host Routerl 172 16 101 101 netadmin3 ip remd rcp enable Configuring the Remote to Send rcp Requests The rcp protocol requires a client to send a remote username on each rcp request to a server When you copy a configuration file from a server to the router using rcp the Cisco IOS software sends the first valid username in the following list 1 The username set by the ip remd remote username command if the command is configured 2 The remote username associated with the current TTY terminal process For example if the user is connected to the router through Telnet and was authenticated through the username command the router software sends the Telnet username as the remote username
14. nds but they offer an alternative that provides faster performance and reliable delivery of data These improvements are possible because the rcp transport mechanism is built on and uses the Transmission Control Protocol Internet Protocol TCP IP stack which is connection oriented You can use rep commands to copy system images and configuration files from the router to a network server and vice versa You can also enable rcp support to allow users on remote systems to copy files to and from the router Configuring the Router to Accept rcp Requests from Remote Users To configure the Cisco IOS software to support incoming rcp requests use the following commands in global configuration mode Command Purpose Step1 ip remd remote host local username ip address Create an entry in the local authentication database host remote username enable level for each remote user who is allowed to execute rep commands Step2 ip rcmd rcp enable Enable the software to support incoming rcp requests To disable the software from supporting incoming rcp requests use the no ip remd rep enable command Cisco 10S Configuration Fundamentals Configuration Guide Release 12 1 JL Fc 251 Configuring Additional File Transfer Functions HZ Configuring a Router to Use rsh and rep amp Note When support for incoming rcp requests is disabled you can still use the rep commands to copy images from remote servers The support for i
15. om its Flash memory You can also configure the router to respond to other types of service requests such as Reverse Address Resolution Protocol RARP requests To configure the router as a server perform any of the tasks in the following sections The tasks are not mutually exclusive e Configuring a Router as a TFTP Server e Configuring a Router as a RARP Server Cisco 10S Configuration Fundamentals Configuration Guide Release 12 1 First Published July 14 2000 Last Updated Oct 1 2002 mw FC 241_ Configuring Additional File Transfer Functions W Configuring a Router as a Server In addition you can configure the Cisco IOS software to forward extended BOOTP requests over asynchronous interfaces Refer to the Configuring SLIP and PPP chapter of the Dial Solutions Configuration Guide for more information Configuring a Router as a TFTP Server S As a TFTP server host the router responds to TFTP Read Request messages by sending a copy of the system image contained in ROM or one of the system images contained in Flash memory to the requesting host The TFTP Read Request message must use one of the filenames that are specified in the configuration Note For the Cisco 7000 family the filename used must represent a software image that is present in Flash memory If no image resides in Flash memory the client router will boot the server s ROM image as a default Flash memory can be used as a TFTP file ser
16. p password type password Specifies the password to be used for the FTP connection ip ftp passive Configures the router to only use passive mode FTP connections or Allows all types of FTP connections default no ip ftp passive ip ftp source interface interface Specifies the source IP address for FTP connections Cisco 10S Configuration Fundamentals Configuration Guide Release 12 1 JL Fc 253 Configuring Additional File Transfer Functions WE Configuring a Router to Use FTP Connections The following example demonstrates how to capture a core dump using the Cisco IOS FTP feature The router accesses a server at IP address 192 168 10 3 with login name zorro and password sword The default passive mode FTP is used and the server is accessed using Token Ring interface tol on the router where the core dump will occur ip ftp username zorro ip ftp password sword ip ftp passive ip ftp source interface tol exception protocol ftp This command allows the core dump code to use FTP rather than TFTP or RCP exception dump 192 168 10 3 This command creates the core dump in the event the system at IP address 192 168 10 3 crashes Cisco 10S Configuration Fundamentals Configuration Guide Release 12 1
17. rotocol udp 111 Provide the access server with the IP address of the diskless sun arp 172 30 2 5 0800 2002 ff5b arpa interface ethernet 0 Configure the access server to act as a RARP server using the Sun Server s IP address in the RARP response packet ip rarp server 172 30 3 100 Portmapper broadcasts from this interface are sent to the Sun Server ip helper address 172 30 3 100 Specifying Asynchronous Interface Extended BOOTP Requests The Boot Protocol BOOTP server for asynchronous interfaces supports the extended BOOTP requests specified in RFC 1084 The following command is useful in conjunction with using the auxiliary port as an asynchronous interface To configure extended BOOTP requests for asynchronous interfaces use the following command in global configuration mode Command Purpose async bootp tag hostname data Configures extended BOOTP requests for asynchronous interfaces You can display the extended BOOTP requests by using the following command in EXEC mode Command Purpose show async bootp Shows parameters for BOOTP requests Cisco 10S Configuration Fundamentals Configuration Guide Release 12 1 Configuring Additional File Transfer Functions HZ Configuring a Router to Use rsh and rep Configuring a Router to Use rsh and rcp Remote shell rsh gives users the ability to execute commands remotely Remote copy rcp allows users to copy files to and from a file system
18. rsh command a shell is started on the remote system The shell allows you to execute commands on the remote system without having to log in to the target host You do not need to connect to the system router or access server and then disconnect after you execute a command if you use rsh For example you can use rsh to remotely look at the status of other devices without connecting to the target device executing the command and then disconnecting This capability is useful for looking at statistics on many different routers Maintaining rsh Security To gain access to a remote system running rsh such as a UNIX host an entry must exist in the system s rhosts file or its equivalent identifying you as a user who is authorized to execute commands remotely on the system On UNIX systems the rhosts file identifies users who can remotely execute commands on the system You can enable rsh support on a router to allow users on remote systems to execute commands However our implementation of rsh does not support an rhosts file Instead you must configure a local authentication database to control access to the router by users attempting to execute commands remotely using rsh A local authentication database is similar to a UNIX rhosts file Each entry that you configure in the authentication database identifies the local user the remote host and the remote user Configuring the Router to Allow Remote Users to Execute Commands Using rsh To
19. s in the example the any clients on network 172 16 101 0 are permitted access to the file Server configure terminal Enter configuration commands one per line End with CTRL Z Server config tftp server flash gs7 k 9 17 1 Server config access list 1 permit 172 16 101 0 0 0 0 255 Server config end Server copy running config startup config ok Server Configuring the Client Router Step 1 Step 2 Step 3 Step 4 Step 5 Step 6 Step 7 Step 8 Step 9 Step 10 Cisco 10S Configuration Fundamentals Configuration Guide Release 12 1 Configure the client router to first load a system image from the server As a backup configure the client router to then load its own ROM image if the load from a server fails To configure the client router use the following commands beginning in privileged EXEC mode Command Purpose configure terminal Enters global configuration mode from the terminal no boot system Removes all previous boot system statements from the configuration file boot system tftp filename ip address Specifies that the client router load a system image from the server boot system rom Specifies that the client router loads its own ROM image if the load from a server fails config register value Sets the configuration register to enable the client router to load a system image from a network server end Exits global configuration mode
20. uter and ping again After you verify the connection ensure that a TFTP bootable image is present on the server This is the system software image the client router will boot Note the name of this software image so you can verify it after the first client boot Cisco 10S Configuration Fundamentals Configuration Guide Release 12 1 Configuring Additional File Transfer Functions A Configuring a Router as a Server W Caution For full functionality the software image sent to the client must be the same type as the ROM software installed on the client router For example if the server has X 25 software and the client does not have X 25 software in ROM the client will not have X 25 capabilities after booting from the server s image in Flash memory Configuring the Server Step 1 Step 2 Step 3 Step 4 To specify TFTP server operation use the following commands in configuration mode Command Purpose configure terminal Enters global configuration mode from the terminal tftp server flash partition number filenamel alias filename2 access list number or tftp server flash device filename Cisco 7000 family only or tftp server flash device partition number filename Cisco 1600 series and Cisco 3600 series only or tftp server rom alias filenamel access list number Specifies the system image to send in response to Read Requests You can enter multiple lines to specify
21. ver for other routers on the network This feature allows you to boot a remote router with an image that resides in the Flash server memory With Cisco IOS Release 11 0 Cisco 7000 family allow you to specify one of the different Flash memory devices bootflash slot0 slot1 slavebootflash slaveslot0 or slaveslot1 as the TFTP server In the description that follows one Cisco 7000 router is referred to as the Flash server and all other routers are referred to as client routers Example configurations for the Flash server and client routers include commands as necessary To configure a router as a TFTP server perform the tasks in the following sections e Performing Prerequisite Tasks e Configuring the Server e Configuring the Client Router Performing Prerequisite Tasks The server and client router must be able to reach each other before the TFTP function can be implemented Verify this connection by pinging between the server and client router in either direction with the ping command An example use of the ping command is as follows Router ping 172 16 101 101 In this example the Internet Protocol IP address of 172 16 101 101 belongs to the client router Connectivity is indicated by a series of exclamation points while a series of periods plus timed out or failed indicates no connection If the connection fails reconfigure the interface check the physical connection between the Flash server and client ro
22. wing command in interface configuration mode Command Purpose ip rarp server ip address Configures the router as a RARP server Figure 16 illustrates a network configuration in which a router is configured to act as a RARP server Figure 16 Configuring a Router as a RARP Server Sun server 172 30 3 100 L E1 172 30 3 4 Router A EO 172 30 2 4 e a Sun workstation 172 30 2 5 g Mac address 2 0800 2002 ff5b D E Cisco 10S Configuration Fundamentals Configuration Guide Release 12 1 Configuring Additional File Transfer Functions Specifying Asynchronous Interface Extended BOOTP Requests Wi Router A has the following configuration Allow the router to forward broadcast portmapper requests ip forward protocol udp 111 Provide the router with the IP address of the diskless sun arp 172 30 2 5 0800 2002 ff5b arpa interface ethernet 0 Configure the router to act as a RARP server using the Sun Server s IP address in the RARP response packet ip rarp server 172 30 3 100 Portmapper broadcasts from this interface are sent to the Sun Server ip helper address 172 30 3 100 The Sun client and server s IP addresses must use the same major network number because of a limitation with the current SunOS rpc bootparamd daemon In the following example an access server is configured to act as a RARP server Allow the access server to forward broadcast portmapper requests ip forward p
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