After some experimentation, I found I can get routing working again - temporarily - by following these steps: run netcfg as root Click the Interfaces tab Select the eth0 interface and Edit it Change my IP number Click Save At this point the route command works again, and I can ping the other machine over the network. However, my IP address has NOT YET CHANGED. So something about the act of changing the IP address in netcfg has fixed the problem, even though the change has not yet taken effect. I still can't make other changes in netcfg; for instance, if I try to change my host domain (which is incorrect), I get the following error: SIOCDELRT: No such process SIOCADDRT: No such device Using ppp does not make the problem come back, but rebooting the computer (and thus finalizing the change to my IP address) does. Ideas? --Ben