Various Wi-Fi devices, especially mobile ones, started to “lose” the router. They can easily find the network, but then are stuck on obtaining the IP address. I guess this is some bug in the DHCP server. Restarting the router usually helps.

I ended up writing a little C# program (binaries, full source, Program.cs) to automate the process.

This may sound awful, but this router has been working longer than my previous LinkSys router that just dies after less than two years in service.

While exploring the router’s built-in web server I found many gems. First off, the login page never returns 401 or 403. If the password is correct, it returns a redirect to the main page, if the password is not correct, it returns a redirect to an HTML page that, among other things, contains the text “Incorrect password”.

Taking password’s MD5 hash is dubbed “encrypt password”:

http://192.168.0.1/login.stm

//Encrypt password
if(typeof(bEncPassword) != 'undefined')
{
    document.tF.pws.maxLength = 32;
    document.tF.pws.value = hex_md5(document.tF.pws.value);
}

The restart script (/cgi-bin/restart.exe) is even funnier. It returns an HTML page if the restart was successful, or 400 Bad Request if the user is not logged in. By the way, no login cookie is sent to the client. The router probably just remembers logged on user’s IP. If someone then hijacks my IP and sends a nasty command from it, the router probably would not know the difference. But then, after all, it’s a home router, bulletproof security is not required.

I also loved the comment in German in /routine_data.js:

// Vordefiniert: VoIP Providerdaten
var voipprovname = new Array("VoIP Account","Other offerer");
var voipprovtxt1 = new Array("DSL Telephone number","Internet call number");

Overall, it was fun, and now I can finally restart the router with one click 🙂