nmap servername
This command will return list of all network ports opens on the server
Example Output
Starting Nmap 4.03 ( http://www.insecure.org/nmap/ ) at 2008-04-28 12:53 PDT
Interesting ports on servername (server_ip):
(The 1663 ports scanned but not shown below are in state: closed)
PORT STATE SERVICE
21/tcp open ftp
22/tcp open ssh
25/tcp open smtp
80/tcp open http
111/tcp open rpcbind
443/tcp open https
873/tcp open rsync
3306/tcp open mysql
13722/tcp open VeritasNetbackup
13782/tcp open VeritasNetbackup
13783/tcp open VeritasNetbackup
