what port do multiplayer games use?

[daguuy]

I have to use a frikin firewall that doesn't let me play online games (other than starcraft). I want to play Halo and CoD and stuff but they never connect. What port do they use? Is it the same one that file sharing uses?

[timmeh87]

only one thing can use a port at a time, so every different program has its own random port number, and it is most often user-changeable.

if you are behind a router you need to forward the ports