Issues with networking on Ubuntu Server 7.10 (Gutsy Gibbon) Beta

I just completed my first install of Ubuntu Server 7.10 (Gutsy Gibbon) Beta and I ran into some networking problems that were difficult to diagnose until I came across the right command to show me what the problem was. Then everything was simple to fix though I’m still at a loss to why the problem occurred in the first place.

During the install I had networking so I was surprised that upon completion of the install and the system was rebooted networking didn’t work. I kept seeing the following error: “SIOCSIFADDR: No such device” whenever I tried to setup eth0 (or eth1). I checked the logs and found this “eth0: forcedeth.c: subsystem: 01043:8141 bound to 0000:00:0a.0” which made me think that the forcedeth module was being installed and assigned to eth0. So at first I tried to look into whether it was some sort of module problem. I used modprobe to remove and install the forcedeth module. I added forcedeth to the /etc/modules file. I read through logs and started searching for answers online but to no avail.

Finally, I had the intelligence to run ip addr. The results of which showed me that the card was actually bound to eth2 instead of eth0. At that point it was simple to run dhclient eth2 to get an ip address and continue on with a functional network configuration. Still, I wish I understood why the interfaces came up as eth2 and eth3 instead of eth0 and eth1 and why the logs mentioned eth0 in connection with the driver module but the only mention of an eth2 was “eth2: no IPv6 routers present” and of course I didn’t think to look for messages about eth2. Maybe this will become clear in the future but for now the lesson is that the ip command is extremely useful in diagnosing networking problems.