Hi, the Port 6000 is X. As it is a robust flexible GUI at allows connections from/to other computers. Closing the port im unsure of, but u can protect it, just change your /etc/hosts.deny and change the entry to ALL:6000 (i think thats the format). that will deny all hosts to port 6000.

alternativly use ipchains/iptables to block out the port on a certain interface.