I run a small, low power machine with two interfaces as a file and torrent server. Both interfaces are on the same LAN. I typically assign different services to different interfaces, such as AFP, SMB, SSH to one and the Azureus to the other. This has worked fine in 8.04 but with 10.04 if I bring up the machine with both interfaces active packets cannot find their way back through my firewall (LAN traffic is fine). A traceroute stops right at my firewall. This is not exclusive to my network environment, either- I've tested with a virtual machine at work as well and packets cannot find their way back beyond the first router. I'm not the best at troubleshooting but the basic network issues so I'm at a loss what occurred between 8.04 and 10.04 that is causing this problem.