Peer-to-peer applications and instant messengers can present special threats to your network’s security. Here’s how you can use HTTP filtering with ISA Server 2004 to block these applications from communicating.
Check out http://techrepublic.com.com/5100-6350_11-6029342.html?tag=search for all the deep details!
Thomas W Shinder, M.D.
MVP -- ISA Firewalls