I've used linux for a while now, but am a relative noob when it comes to security issues, and have run into a problem:

my proxy/file server for my home LAN crashed under fairly suspicious circumstances, so after a clean re-install i've decided to up the security as much as possible, starting with closing any unused ports, an nmap portscan reveals that an unknown service is using an open port.

PORT STATE SERVICE
22/tcp open ssh
111/tcp open rpcbind
113/tcp open auth
548/tcp open afpovertcp
###/tcp open unknown


How would I close this port? I am guessing that having such an open port is a huge security problem, and so appreciate any assistance.

-Rysio

First off... why are you hiding the port #? Knowing it might help us figure out the problem. Secondly, as root, run 'netstat -pantu'. This will show open ports and the process controlling the port.

Thanks alot, this solved my problem... I found the process keeping the port open, the port was being used by rpc.statd
Thanks again