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But all was hopelessly out of date.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 192.168.1.253 (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 192.168.1.49 (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_22.214.171.124_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 192.168.1.49 put WL500gp_126.96.36.199_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 192.168.1.3
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.