Question: What resources will help to figure out what port numbers are used by different programs?
The IT Guy says:
Richard Akerman has several helpful pages relating to port number issues, including one on TCP/IP ports, and another on dangerous TCP/IP ports. The latter site may be of more interest for individuals using high-speed internet services like cable and DSL modems at home, but the issues are applicable within the school environment as well. Older "stateless" firewalls require separate ports to be opened or closed on the network, and the configuration of these devices can be quite tedious. Newer "stateful" firewalls allow network administrators to exercise much more robust control over the incoming packets authorized to traverse the network. In both cases, effective firewall management requires an understanding of the network design and the traffic authorized to move across it. Stateful firewalls track the "state" of TCP/IP packets on the network: whether they are new, related, established, or invalid. Stateful firewalls can authorize only TCP/IP connections that originate within the organization, and thereby prevent network intrusions from the outside that would be permitted by stateless firewalls. A forthcoming article I am writing for the T&L print magazine will explore these and other network security issues in greater detail.