In another post on router forensics I mentioned the possibility of communicating with a Linksys router through what I thought were unused connectors on its PCB. After all, it’s very common to find extra holes and tracks whe manufacturers are using the same PCB design across different models. It turns out they are indeed working connections to the IC chips, used by Cisco/Linksys for installation and diagnostics, and the cables for them are readily available. A hacker called Wild Bill had discovered this when trying to unbrick a router after a firmware change went horribly wrong (video below). One thing I’d add is a parallel connection might not be necessary, as communications should be possible through the RS232 connectors.
Anyway, I’m expecting a couple more WRT54G devices, and will post more on this after I replace the firmware, set up IPv6, etc.
UPDATE: If the router’s power light is flashing but there’s no DMZ light, ignore the other online suggestions. Open a terminal/command line, run ping continuously with:
ping -t -w 2 192.168.1.1
And keep your eye on the output. Initially it’ll say ‘host unreachable’.
Next, hold the reset button for ten seconds, remove the power cable, wait another ten seconds before re-attaching it.
After a few moments, the ping output should show the router starting to return packets. Now enter http://192.168.1.1 in the browser’s address bar. If the Management interface appears, upload the official firmware. It might take several attempts before it’s successfully installed.