Monday, March 1, 2010

PPPoE with German 1&1 (1und1)

Boring alert: I'm leaving this here just in case it's useful for someone. If you don't {live in Germany, have a 1und1 connection, want to use the Fritz!Box as a modem} you probably don't want to read this

Germany has very nice network coverage (at least compared to Spain). At home, I have a VDSL2 connection, 50Mbps downstream, 10Mbps upstream with 1&1. It includes some online movie rental, online storage, VoIP landline flatrate and a very fancy router to manage it all (FritzBox!Fon 7390), with Phone<->VoIP converter, dual radio WiFi, and lots of other stuff (even console access to the linux underneath, but you need to dial some stuff on a phone to get there, and I have no phone...)

The problem is that the bandwidth is a bit too much for this thing to handle. It manages very well web browsing, ftp upload and downloads and all sorts of usual navigation, but it chokes on BitTorrent usage. Even with just 400 connections it freezes after a few hours, requiring a reboot.

Solution? The web interface allows to use it just as a modem, with a very handy option just in the menu! I have the "advanced options" (Einstellungen>Ansicht>Expertenansicht) active, maybe it's not possible without it. Kudos to Fritz, the firmware might have some bugs / stability problems but their attitude is great. They give the user complete control over the hardware and it looks like they really care about the customer (when I reported another bug I got to talk with a technician after just one email exchange with some operator).

Problem? Of course there is one! It wouldn't be funny without it! After following the super-easy PPPoE guide it wouldn't work. Looking at /var/log/errors.log it said something about an authentication error, and the PAP protocol error was "profile not sufficient". Weird, huh? After some googling it turns out that the credentials 1&1 gives you to connect are not complete. They are in the form 1und1/ but the real PPPoE username is ONELETTER1und1/(SOMESTUFF)

How to find out the first letter and the stuff inside the parens? Maybe you could call 1&1 but if your german is not that... well, german, you can find it out with a packet capture. Yes, a packet capture, of the original PPPoE handshake. No, I'm no kidding. No, you don't need and specialized DSL-sniffing gizmo. Just go to http://ROUTER_IP/html/capture.html, force a reconnect from the main webpage and you just captured the handshake on the DSL interface.

Really really nice job, Fritz, I am impressed. Arguably "lucky for us", the PAP authentication is in clear text, so just get the full username, and put it in the peer file, in the pap-secrets, and you are good to go! The linux box will have a public IP so don't forget a firewall and turning everything you don't need off.