Services (not) needed/secure?/ How to disable?

Hi, the following services are running on my machine: 111/tcp => portmap (user: bin) 111/udp => portmap (user: bin) 113/tcp => in.identd (user: nobody) 515/tcp => lpd (user: root+) 6000/tcp => X (user: root) Now my questions: Is any of them insecure? Are they required for the system or can I disable them? If X is not required, where have I to change sth that it will no longer listen on port 6000? Whats the general task of portmap and identd? thx Markus