To use CU-SeeMe through a firewall, you must open certain ports on your firewall to allow data to transfer freely. The ports are outlined below. These ports must be opened to allow communication in both directions, both incoming and outgoing. Currently, CU-SeeMe does not work through a proxy server doing Network Address Translation .
Proxy servers do network address translation.
If you are not sure if you are networking through a proxy server, contact your network administrator.