netstat(8) -tlpn
Print network connections, routing tables, interface statistics, masquerade connections, and multicast memberships
-l, --listening
    Show only listening sockets.  (These are omitted by default.)
-p, --program
    Show the PID and name of the program to which each socket belongs.
--numeric , -n
    Show numerical addresses instead of trying to determine symbolic host, port or user names.
source manpages: netstat