probably best to find out what others are using in your college and see how they do it
for gnutella i think it needs to get port 6346 through the firewall
Firewall:
A firewall is a protective mechanism that allows only computers inside the firewall to make network connections out through the firewall; it will not allow outside computers to make connections into a given computer network. If a servent outside the firewall tries to download a file from a computer inside the firewall, the firewall will prevent this connection from being made. Usually, this results in a push request message being sent to the servent inside the firewall requesting that that servent connect through the firewall and upload the desired file. If the servent requesting the file is himself behind a (different) firewall, then this upload will also be blocked, and there will be no way for the file transfer to occur.
http://www.limewire.com/english/content/firewalls.shtml