dolphin-emu/dolphin — pull request #374 by ToadKing (2014-05-16 00:36:38+00:00)
Title: make IOCTL_SO_GETHOSTID more accurate on Windows

This is done by looking up the default route and using the IP of the interface attached to it. This allows people on the same network to connect through WFC games.

There should be a Mac/Linux equivalent but I'm not knowledgeable enough to implement that, plus not being able to test it.