Can't connect nonlocally after 12.10 upgrade
I'm running Kubuntu 12.10, upgraded from 12.04. After the upgrade I discovered that although I can access my local network without any trouble, I can't access any remote locations -- not even by IP number. So the difficulty probably has to to with routing or some related issue. Since I do no better with IP numbers than with URLs, it's almost certainly not nameserver-related. And since local access works correctly, it's not a low-level problem such as something wrong with Network Manager. Since I still can access the Net using Windows on the same machine, it's not anything with my router or beyond, either.
I have another laptop sitting next to this one, also running Kubuntu 12.10. On the other laptop, everything works, so I can make comparisons. On the working laptop, the output of netstat -a starts with a number of tcp lines; on the troublesome one, those lines are not to be seen.
I'm not expecting a solution from here, but at least I'd like to know what kinds of things I should be investigating and where I can learn how the routing mechanisms work.