Here's a patch to expand the capture filters and the client detection to use the full 9000-9007 world server port range. It also filters out broadcast and multicast traffic, so that should quiet down the logs a bit regarding weird packets (like BlueAdept's example from upthread).
Running around in game, it seems fine. I've tried it with/without session tracking, and with/without specifying my host IP and haven't had any noticeable issues.