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Ian Chakeres
Outline
Linksys WRT54g
OpenWRT
Installation and configuration
Creating a custom image
Open discussion
Resources
DEMOs throughout
Ian Chakeres
HardwareLinksys WRT54g - retail approx. $70Wired: 5 ports - ADMtekWireless: IEEE 802.11g - Broadcom
Dual RP-TNC antenna portsAdjustable transmit power
FLASH: 4MB, 2MB usableRAM: 16MBCPU: 200MHz MIPSOS: LinuxOpen Source
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New Box
WAN: DHCP
LAN: 192.168.1.1
http administration
DEMO
WAN setup required for certain operations
boot_wait=on, loading new firmware
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boot_wait
boot_wait=on
safe boot mode - 3 to 5 seconds
eth0 responds ARP and tftp requests
allows firmware loading
boot_wait=off by default
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Setting boot_wait=on
Management page ping exploit;cp${IFS}*/*/nvram${IFS}/tmp/n;*/n${IFS}set${IFS}boot_wait=on;*/n${IFS}commit;*/n${IFS}show>tmp/ping.log
DEMO
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Distributions
Linksys GPL
Preinstalled firmware
SveaSoftThe Sveasoft firmware adds a host of new features to your Linksys WRT54G or WAP54G router - including increased performace.
Ad-hoc mode
OpenWRT
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OpenWRT
Minimal base providessquashfs and jffs2network initializationfirewalldhcptelnetbusybox environment
Everything else is a package
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OpenWRT
Building a the image> wget http://openwrt.org/cgi-bin/viewcvs.cgi/buildroot/buildroot.tar.gz> tar xzvf buildroot.tar.gz> cd buildroot> make
Takes about one hourrequires internet access
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Loading the New Image
Configure the WAN interfaceConfigure your interfaceTFTP always 192.168.1.1>tftp 192.168.1.1tftp> binarytftp> rexmt 1tftp> tracetftp> put openwrt-g-code.bin
Unplug-plugin WRTDEMO
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firstboot
Wait for firstboot to complete - IMPORTANT
Power light will stop blinking
DMZ light will turn OFF
DO NOT INTERRUPT OR REBOOT
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Logging In
Configure your interface
Telnet 192.168.1.1
DEMO - login, filesystem
If already configured, IP might be different
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Filesystem Manipulation
jffs2 points to squashfssaves space
Editing filesremove linkcopy file from /romedit
DEMO - unlink, copy, edit file
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NVRAM
Non Volatile RAMImportant things live here
nvramshowget nameset name=valuecommitDEMO - nvram
WARNING - RESET button
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after_firstboot.nvram
after_firstboot.nvram NODEID
192.168.10.NODEID wired uplink
192.168.16.NODEID wireless
192.168.17.NODEID wired backplane
DEMO - after_firstboot.nvram
Sets up lots of NVRAM variables
wl0, wifi, wan, lan, etc
REBOOT - causes variables to take effect
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Basic Custom Image
Lots of modifications and additionsConfiguration
dns, routing tables, startupModules
ipv6, netfilterSoftware
mne, nrlolsr, mgenDEMO - modules, config, software
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Package Management
ipkg
update
install, upgrade
remove
list
status
DEMO - ipkg
dropbear (ssh), tcpdump, olsrd (unik)
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Creating a Custom Image
Important locationsbuild_mipsel/rootbuild_mipsel/release/src/linux/linuxuse find . -name “x” -print
Building and rebuildingpre_recompile_kernel.shmake
Some files/directories get overwritten
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Installing and Configuring New Image
Same process as new box
TFTP 192.168.1.1 unplug/plugin
IP address after load will be configured
after_firstboot.nvram may be unnecessary
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NRL and the WRT54g
NRL-OLSR, MNE, MGEN, ssh, IPv6, WEPCheap laptop replacementQuick demosLarge scale testsEasy setupCustomizable
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Problems
Ad-hoc mode
Failed installation
always set boot_wait=on
attempt reinstall using tftp
WARNING - RESET button
de-bricking instructions available
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Resources
Lots of content verbatim from belowOpenWRT
http://openwrt.orguser guide, NVRAM, faq, forums, wiki
Linksys GPLhttp://www.linksys.com/support/gpl.asp
Seattle Wirelesshttp://www.seattlewireless.net/index.cgi/LinksysWrt54g
SveaSoftDe-brick - http://openwrt.org/forum/viewtopic.php?t=17
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