So Proud of Myself

Wednesday 9. April, 2008

Today I finally managed to repair my A-Link RR24AP(c) adsl-modem. The problem was that the wireless side didn’t function at all because the boot environment of the modem was corrupted. The corruption was my fault as I accidentaly used a wrong power source which wasn’t powerful enough, all I could see was the lan-connection light flickering.

Few weeks ago I contacted A-link’s tech support and they told me to send the modem to their technicians, but I didn’t bother to that as the warranty period had ended quite some time ago.

The modem accepts ssh-connections for controlling it and a linux shell/toolset, busybox. Boot environment configuration can be accessed through /proc/ticfg/env -file. A quick look into it and some knowledge from RouterTech’s forums and the modem’s system log revealed that WLAN_EEPROM-values were missing. I don’t know exactly what these values are but I do know that without them the wireless doesn’t work.

I found a recovery software through the same forums but the program didn’t start. I crashed immediately. I was very disappointed as it was my only hope. As I knew that I needed those WLAN_EEPROM-settings so it came to my mind to take a look on that program with a hex editor (Notepad++ with hex editing plugin, in case you want to know…) and indeed there they were! Apparently it was a template of the eeprom-settings, but still I got my hopes up again!

I didn’t expect this template to work directly which was then confirmed when I tried it. Again the answer was found in RouterTech’s forums. Some other guy had the same problem of missing/corrupted WLAN_EEPROMs and some other guy told him that WLAN_EEPROM8-line contains a hardware specific id in REVERSE order (12 34 56 would become 56 34 12). Modifying that line did the trick! The WLAN-led lit up! I had restored the right WLAN_EEPROMs (WLAN_EEPROM0-WLAN_EEPROM14) and I had a working wireless access point. One problem, though, the modem though that the BSSID was 00:00:00:00:00:00 THAT IS NOT RIGHT! (and only my laptop’s Intel 3945 detected it, my buffalo usb-wlan stick didn’t see anything).

And to the Google we went… it turned out that WLAN_HWADDR0 should be set and contain the MAC-address of the wlan-system.

Now the modem is under testing and seems to run just fine.

(I don’t publish the WLAN_EEPROM-values here because I don’t know if  that would be legal)

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