Supposing I have a network process identified through netstat, how would I drop the process? Do I have to figure out what it is through ps and then kill it? Or is there an easier way?

Also, if I have a user I want to log off, is there a way as root to force this?

The best way I know to stop a process from using a certain port is to figure out what process it is first, then either (before it starts doing it) prevent it from using that port, or (if it's already happening) kill the process. Running 'nmap -v localhost' might give you some more information about what is going on. One notorious port-listener is X, which by the server defaults listens for remote connections on port 6000. As to forcefully logging off another using, I'd just kill the shell they're using, or perhaps if it's a SSH connection, kill and restart sshd.