Thursday, 26 February 2015

Restore original firmware on an ASUS WL-500GP

I had a Asus WL500GP sitting on a shelf for quite some time. That box had been abused under OperWRT as Samba File Server, Asterisk Server, Web Server, mail server, Zork server, etc.
But all was hopelessly out of date. So I decided to first restore it to is's original condition. To achieve that I had to employ a mix of various techniques described on the Interwebs. The Asus Firmware Restoration Tool did not work for me and I was briefly worried that I had bricked this neat little device. Fortunately it is pretty tough.

Here is what I did:

Restore original ASUS firmware on WL500GP:

-Turn off Windows Firewall
-Set PC to static IP (or whatever can't get in the way)
-plug PC directly into lan port 1 (probably not really necessary, but it cuts out all the noise from the rest of my network when using Wireshark)
-Unplug power from router
-Start Wireshark on PC
-Keep black restore Button (not the EZSetup!) pressed while plugging power back in

-Look out for gratitious ARP packets:
2577    1838.485014    AsustekC_e4:XX:XX    Broadcast    ARP    Gratuitous ARP for (Request)

I have no idea where that .49 address comes from but now we have the target address.

Please note that contrary to other information on the web, my router has neither issued DHCP to the PC nor reacted to the ASUS Firmware Restoration tool. That is why I had the PC set to a static IP.

-Now TFTP the firmware image to the router

 Directory of C:\Firmware\Asus\FW_WL500gP_1977

21.10.2008  22:00    <DIR>          .
21.10.2008  22:00    <DIR>          ..
14.05.2008  12:00         7'237'632 WL500gp_1.9.7.7_TW.trx
               1 File(s)      7'237'632 bytes
               2 Dir(s)  237'154'689'024 bytes free

C:\Firmware\Asus\FW_WL500gP_1977>tftp -i put WL500gp_1.9.7.7_TW.trx
Transfer successful: 7237632 bytes in 15 seconds, 482508 bytes/s

-I then had to wait for a while (approx 5 minutes) and the router came back. - With address
That was the one I had stored in NV.

-Don't forget to turn your PC's firewall back on and set the IP assignment to DHCP.

After inspecting what use the original firmware does for the router, I decided to upgrade to OpenWRT Kamikaze.

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