ip46nat User's Guide
Contents
1. 3 5 Firmware upgrade using linux console To perform firmware upgrade from OpenWRT i e when your LinkSys device was flashed already mtd tool must be used Copy openwrt brcm47xx squashfs trx file to the tmp directory Note that this is a different image file than used in the web interface Copy it to your LinkSys device scp openwrt brcm47xx squashfs trx root 192 168 1 1 tmp This command will copy required firmware image to tmp directory Change to that directory and begin flashing using following command cd tmp mtd r write openwrt brcm47xx squashfs trx linux After flashing is complete device will reboot It takes up to 2 minutes to finish flashing and rebooting Please note that after such firmware upgrade all possible changes made to the router configuration will be lost That includes all software packages installed and all configuration changes Note bin and trx firmware image files contain the same image but trx is a raw image while bin has extra headers for the purpose of being recognised as a valid image by the original web interface 3 6 Installing ip46nat kernel module To perform IPv4 to IPv6 NAT a separate kernel module have been developed For the easiness of installation it is being distributed as a ipk package Please install it as any other ipk packages ipkg install http wiki openwrt org InstallingWrt54gl After installation is complete ip46nat kernel module may be loaded using following comma2. address embedded on 4 least significant octets If incoming IPv6 packet meets those criteria it will be converted to IPv4 packet Header checksum will be calculated TTL will be decreased and packet will be sent For converted IPv4 packet to be transmitted successfully IPv4 forwarding must be enabled IPv4 routing must also be configured See section 4 for details 6 Compilation tbd 6 1 Linux for LinkSys OpenWRT tbd 6 2 ip46nat kernel module tbd 6 3 ip46nat kernel module as an ipk package tbd 6 4 dibbler software tbd 6 5 dibbler software as an ipk package tbd 7 Miscellaneous topics tbd 8 Links Following links are recommended reading e http klub com pl ip46nat ip46nat project homepage e http openwrt org OpenWRT project website e http downloads openwrt org kamikaze docs openwrt html OpenWRT manual 9 Contact Author of this project can be reached using e mail mailto tomasz mrugalski gmail com
3. this configuration after every firmware upgrade Also it is its default factory configuration 3 2 Firmware upgrade using original web interface Before attempting to install Linux on LinkSys device make sure that this particular model is supported Please consult http wiki openwrt org TableOfHardware Linux installation on Linksys is being performed as a firmware upgrade During the first installation original web interface provided by LinkSys should be used From PC using the same address space see section 3 1 use web browser to connect to your LinkSys web interface See Fig 2 below 0 Firmware Upgrade Iceweasel 00e m ile Edit View History Bookmarks Tools Help I gt O http 192 168 1 1 Upgrade asp Gl Google Auto Biz Devel Doc Gry GiPv6 Linux Mieszkanie Misc Newsy Ph D Portale Space Proble Openw E Openwr E Openwr E Openwr j OpenWr jOpenw O Fir B LINKSYS A Division of Cisco Systems Inc Firmware Version v4 30 12 Wireless G Broadband Router WRT54GL Administration Setup Wireless Security Access Restrictions psec Administration Status Management Log Diagnostic Factory Default Firmware Upgrade Config nent Upgrade Firmware Click on the browse button to select the firmware file Firmware Upgrade to be uploaded to the Please select a file to upgrade fn openwrt wrtS4g squas Browse UC
4. P Warning Upgrading firmware may take a few minutes please don t Click the Upgrade button turn off the power or press the reset button to begin the upgrade process Upgrade must not be interrupted MMM More Upgrade must NOT be interrupted Done S FA Adblock Fig 2 Firmware upgrade using original web interface Select appropriate firmware image i e file that ends with squashfs bin and is corresponding to the name of used device There are some sanity checks in the firmware upgrade procedure but using wrong image may result in rendering the router unusable You may want to check supported hardware list http wiki openwrt org TableOfHardware action show amp redirect toh Please verify that you are using proper firmware After firmware was uploaded flashing takes place It can take up to 2 minutes After completion router will reboot Make sure to not reboot or power off the router before it finishes flashing It also may be beneficial to read following installation guide http wiki openwrt org lnstallingWrt54gl 3 3 First connection After performing firmware upgrade it is possible to connect to the router using telnet command Please run following command telnet 192 168 1 1 from a PC console See fig 3 for example session There is no root password Please change root password by issuing passwd command After this operation telnet service will be disabled SSH will be enabled i
5. enation of the P prefix v6prefixp parameter specified during module insertion and IPv4 address Destrination IPv6 address will be created as a concatenation of the M prefix v6prefixm parameter specified during module insertion TTL field will be copied and decreased by 1 For converted IPv6 packet to be transmitted successfully IPv6 forwarding must be enabled IPv6 routing must also be configured See section 4 for details Please note that L4 layer TCP UDP ICMP etc checksums are not modified in any kind That means that After IPv4 to IPv6 conversion packets will not be accepted by destination router They must be converted back to IPv4 That should not pose any concers however as routers are not supposed to intestigate L4 content at all Thus packets must be converted back to IPv4 before they reach their destination Matched packet information will be reported in the following manner HIPv4 rcvd rcvd so far 3 src 192 168 1 100 dst 192 168 1 1 looking for 192 168 1 0 24 5 2 IPv6 to IPv4 NAT Once IPv4 packets are sent as IPv6 it is expected to receive responses They are to be received as a IPv6 packets Source IPv6 address will belong to the M prefix v6prefixm parameter used during kernel module insertion and will contain source IPv4 address embedded on 4 least significant octets Destination IPv6 address will belong to the P prefix v6prefixp parameter used during kernel module insertion and will contain destination IPv4
6. into full IPv6 addresses using 2 extra prefixes M and P Returning IPv6 packets will be converted back to IPv4 1 2 Phase 2 PPP L2TP tbd 2 Project status Linux booting on LinkSys done ip46nat kernel module developed done ip46nat module ported to LinkSys done prefix delegation mechanism in dibbler modified done dibbler port to LinkSys work in progress ported crashes documentation work in progress 3 Installation To complete installation several steps are qreuired Following sections describe how to achieve specific goals In general there are several approaches 1 Install required software i e modified Linux kernel ip46nat module on a PC machine and use it to perform IPv4 IPv6 NAT This scenario may be used as an preliminary validation scenario 2 Install Linux on LinkSys WRT54 system install ip46nat module 3 1 Connecting LinkSys Before any configuration or firmware modification make sure that you have full connectivity to your LinkSys device LinkSys devices by default use 192 168 1 1 address so to communicate with it another address from 192 168 1 0 24 pool is required For example PC may be configured to use 192 168 1 100 24 address To check if you have connectivity with LinkSys device use following command ping 192 168 1 1 Make sure that you have LinkSys connected using the rightmost socket See Fig 1 below Note IPv4 address set to 192 168 1 1 is a LinkSys default setup It reverts to
7. ip46nat User s Guide Author Tomasz Mrugalski version 2008 06 04 Table of contents TProject OV EL VIC e ed e de O Almaden cats ed LLP hase IPZFtO IPVO NA o O R AO SE rtf Eo FZPRSE 2 PPPZ UD piso facie iit ata R b A R it e AA a TIS PEO SCL SEAS PG ARCO RA A AN cs A A EN 3 2Firmware upgrade using original Web INter ace oooccnoncnnnnconcnoccnnnnncnnncnoncnnnnnnnn nono acc nnnno nn corno 3 3FIrSt COMME SELON iii na dd 3 4Package installation ui dias 3 5Firmware upgrade using linux console ooooooccnonocononoconnncconnccnonnncnnnnncnnnononnnnncnnonnonnnnnnncnnnonnnnns 3 6Installing ip46nat kernel modulaci n ricino l drenados dais 4Network configuration ii ida INAT OPE Ansi EAC 5 PYA tO PO NA doo tl ds ollo ll oe 3 2IPYG TO TP yA NA Bao a A GA R O A a AO A R OR GRA R R O OOO i o GO 6 llini for LIRKSYS Ope WRT di OO AR O AEO 6 2 ip4Onat kernel modula da wa ACE 6 31p46nat kernel module as an ipk package ccceessecssscecescecesneeceeeeeceeeeeceeececseeeeeeeeeeenaaeeeeeeeeees O a e AE 1 Project overview Goal of this project is to provide solution for seamlessly forward IPv4 traffic over IPv6 networks There are two possible migration modes IPv4 to IPv6 NAT see section 1 1 for details and IPv4 over PPP over L2TP over IPv6 1 1 Phase 1 IPv4 to IPv6 NAT First approach to the IPv4 over IPv6 network assumes that incoming IPv4 packets will be converted and forwarded as IPv6 IPv4 addresses will be expanded
8. mpile and run Linux kernel with ip46nat module on a PC For a details regarding module compilation see section 5 4 Network configuration Before attempting to perform configuration it is strongly recommended to be familiar with the following guide http wiki openwrt org OpenWrtDocs NetworkInterfaces All LinkSys WRT routers use one common ethernet interface duplicated using different vlans In the latest OpenWRT version that is being reported as eth0 eth0 0 eth0 1 etc To enable IPv4 and IPv6 forwarding use following command echo 1 gt proc sys net ipv4 conf all forwarding echo 1 gt proc sys net ipv4 conf all forwarding To configure routing ip command may be used Assuming that we want to NAT traffic from 192 168 1 0 24 to 2000 64 following command may be used ip route add 192 168 1 0 24 dev eth0 0 ip route add 2000 64 dev eth0 1 5 NAT operation After module is loaded see section 3 6 for details module will start printing information about all received IPv4 and IPv6 traffic Packets that match configured criteria are marked using When match is found packet will be recoded and transmitted 5 1 IPv4 to IPv6 NAT During module insertion v4addr parameter is specified It is being used as a source IPv4 address filter used with 24 bitmask For example if v4addr is equal to 192 168 1 0 all incoming traffic from 192 168 1 0 24 network will be translated to IPv6 Source IPv6 address will be created as a concat
9. nd insmod lib modules 2 6 23 17 ip46nat ko v6prefixm 2000 v6prefixp 3000 v4addr 10 10 1 0 Module reports its operation using normal kernel messages To see kernel output dmesg command may be used It also appears to be useful to filter dmesg output using tail command To see last 10 messages use following command dmesg tail 30 After module is loaded it reports opertion readiness and begins to filter incoming traffic immediately IPv4 IPv6 NAT module loaded v prefixp 3000 v6prefixm 2000 v4addr 10 10 1 0 Handlers for IPv4 and IPv6 installed HIPv4 rcvd rcvd so far 1 src 192 168 1 100 dst 192 168 1 1 looking for 10 10 1 0 24 HIPv4 rcvd rcvd so far 2 src 192 168 1 100 dst 192 168 1 1 looking for 10 10 1 0 24 HIPv4 rcvd rcvd so far 3 src 192 168 1 100 dst 192 168 1 1 looking for 10 10 1 0 24 Kernel module may be unloaded at any time To do so use command rmmod ip46nat After kernel is unloaded statistics are being presented To see them use dmesg command Handlers for IPv4 and IPv6 removed IPv4 IPv6 NAT statistics IPv4 to IPv6 packets 0 IPv6 to IPv4 packets 0 IPv4 rcvd 74 sent 0 IPv6 rcvd 0 sent 0 IPv4 dropped too large 0 IPv4 dropped no route 0 IPv6 dropped no route 0 IPv4 dropped transmission failed 0 IPv6 dropped transmission failed 0 IPv4 IPv6 NAT module unloaded Note from the early demo perspective it is also possible to co
10. nstead Note that ssh requires some time 30 seconds to generate keys so it will reject any connection attempts at that time gt Terminal 0008 gt y mc raporty photos x mc Imnt cdrom Doc x imc devel openwrt k x Terminal ime x built in shell ash ot changed by uname Fig 3 Linux installed on LinkSys device 3 4 Package installation Software installation is being done using ipk packages To install a package please copy it to tmp directory e g using scp command run on a PC scp mtd_6 mipsel ipk root 192 168 1 1 tmp After package is transferred to the router use following command ipkg install package name ipk to install package For example to install mtd use following command ipkg install mtd_6 mipsel ipk Following packages are currently recommended e mtd mtd is tool used to flash router That is the preferred way to flash router once Linux have been installed e ip powerful tool used for network configuration e iptables optional package may be used to configure IPv4 firewall and or IPv4 only NAT e ip6table optional package may be used to configure IPv6 firewall and or IPv6 only NAT e uclibcxx C library required to run all software written in C e g dibbler software e dibbler client DHCPv6 client used to retrieve configuration e dibbler server DHCPv6 server used to distribute addresses and configuration parameters to other nodes
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