A number of SeattleWireless geeks and I have been working on getting a shell on the Linksys WRT54G access point. It is in fact running Linux 2.4.5 with a number of interesting bits in the filesystem (namely full iptables support, zebra, bridging, and even a Rendezvous responder).
Of course, that’s not nearly enough for me. I want NoCat running on this puppy (probably NoCatSplash or Cheshire first, NoCatAuth to follow) along with IP tunnels, maybe vtun, some monitoring code, and maybe even some mesh bits. Since their kernel apparently supports loadable modules, this is all entirely possible. Almost.
We’re very close to getting a custom firmware on this puppy, but I’m currently stuck trying to compute a CRC value that the AP will accept (details are up on the SeattleWireless site).
I’ve just sent this comment to Linksys. It probably won’t amount to much, but you never know.
Hello-- I am very excited about your decision to include Linux and other GPL code in your recent 54G line. It appears from recent firmware updates that you have very interesting and ambitious plans for this line of equipment. I was wondering if you have published the format of your firmware update files. Parts of it are obviously a CramFS archive and Linux kernel, as well as various header bits. I imagine a CRC of the file is involved for error checking purposes, and required for the AP to accept new firmware. If the open source community were provided technical details about your firmware file format, I believe you would see an unprecedented interest in your 54G line. The ability to run custom Linux software on a commercial access point would certainly make it one of the most desirable access points on the market. The lack of documentation for the firmware header (particularly the CRC and other error checking) currently make it difficult to fully customize the 54G line. My particular interest is in extending your hardware to support NoCatAuth (http://nocat.net/), the open source captive portal implementation, as well as other community network oriented software. This may be outside the scope of your original plans with the 54G line, but please consider the potential benefit of providing the wireless community networkers with this information. Best regards, --Rob Flickenger
So, while we wait for a reply from Linksys/Cisco, who in the audience is good with bit math?
Had any luck dissecting the Linksys WRT54G firmware?