Does iPrism only filter port 80?

In iPrism, when using Bridge (transparent) mode (aka Bridge (transparent) mode), Kernel level filtering analyzes packet traffic, looking for HTTP streams regardless of port number. It will monitor & block HTTP traffic going out on any port.  

iPrism also filters HTTPS traffic, and IM/P2P traffic. To learn more about iPrism port assignments, see:

How do I Change or Add iPrism Port Assignments?

Note: If your network contains a proxy server, traffic can be filtered before it reaches the proxy server by configuring iPrism to filter the proxy port used by your proxy server.