I know this is an old post but just in case anyone reads through it with a similar problem I wanted to follow up and write down what my problem was.

It turned out that the way my NIC was being called via RedHat caused it to be unable to communicate with my SMC EtherEZ Hub 3605T (Ethernet Hub). When I hooked it up to another router (or directly into my modem) everything worked fine.

The strange part was that Windows would communicate with it just fine. I suspect that it was some sort of low level service call error.