Eth0 and ppp0
I didn't have a network at home and thought it was about time I set one up. So I pluged in a realtec card, plugged in a hub and was really amazed at how easy the basic set up was. The system was attempting to lull me into a false sense of security so that i am unprepared for the next blow.
I connect to the internet from home using either a dialup or gprs connection. (that's because internet service providers in my county (Sri Lanka) are totally unaware that the second letter in ISP stands for service. Anyway soon as i plugged in my network card I found that i couldn't connect to the rest of the world with any of the three dialup accounts I use or with my GPRS connection.
Inspection of the routing table showed that it's configured correctly just to be sure i violoated the old adage "don't fix it if it is not broken" and did indeed manage to break up the routing table. This was in fact the first time I played around with the route command in two years so it didn't take much effort to mess it up.
In the end I restored the entire etc folder from a backup, unplugged the network card and installed it again, guess what it works now. Linux is beginnning to look more and more like windows.
As a footnote I needed to setup a NAT so that other computers at home can go through my computer as well. I have long forgotten how to do this but help wasn't very hard to find. The linux NAT Howto is the source of information. All I need to do is enable ipforwarding add and a simple rule to iptables.