Where to find info on program susing different ports?

[Svante Signell <svante.signell@telia.com>]

Having port watching tools running one experiences a lot of
attacks/attempts ot use various ports. How to find out which orts are
used by which program s (both in the *nix and win* world).

Some examples, (cut from /etc/services)
Known:
ftp             21/tcp
telnet          23/tcp
www             80/tcp          http            # WorldWideWeb HTTP
sunrpc          111/tcp         portmapper      # RPC 4.0 portmapper TCP
socks           1080/tcp                        # socks proxy server

Unknown:
netbios-ssn     139/tcp                         # NETBIOS session service
asp             27374/tcp                       # Address Search Protocol
port 1214/tcp? morpheus

BTW: Setting up firewall with fwbuilder, but this tool seems to be
requiring non-trivial effort. Examples, or other tools?