toucheatout 2006-03-26 03:38 IT
You may find a more complete list in /etc/services. A simple lookup on a search engine should yield a decent answer.
Well-known TCP ports
20/21: File Transfert Protocol a.k.a. FTP (20: data/21: control) - passive FTP only uses 21 and some high port (data transfer modalities negociated and transfer itself initiated by the client).
23: Telnet (unsecure version of ssh, can also be used to open a simple connexion, see above).
25: SMTP (Simple Mail Transfert Protocol).
43: whois.
79: finger.
80: HTTP (HyperText Transfer Protocol).
110: POP3 (Post Office Protocol 3).
111: portmapper (RPC-related).
119: NNTP (Network News Transport Protocol).
123: NTP (Network Time Protocol).
135, 137, 139 (and 445): NETBIOS and other windows protocols.
143: IMAP (Internet Message Access Protocol).
389: LDAP (Lightweight Directory Access Protocol). Follows X.500 directory services specifications.
443: HTTPS (HyperText Transfer Protocol over Secure socket layer).
465: SSMTP or SMTPS (SMTP over SSL)
515: LP (Line Printer). Also known as "printer".
631: IPP (Internet Printing Protocol).
636: LDAPS (LDAP over SSL).
993: IMAPS (IMAP over SSL).
995: POP3S (POP3 over SSL).
Unpriviledged, more specific well-known ports (usually tcp and udp)
1080: SOCKS (SOCKet Secure). Proxy server.
1099: RMI registery (java Remote Method Invokation registry).
1194: OpenVPN.
1214: Kazaa.
2049: NFS (Network File System).
2401: CVS (Concurrent Versioning System) pserver.
3128: SQUID web proxy.
3306: Mysql Database.
3690: SVN (SubVersioN).
4662: EMule default TCP.
5060: SIP (Session Initiation Protocol).
5432: PostgreSQL Database.
6000-6007: X Window System.
6346: Gnutella.
8080: WWW caching service.
10080 -> 10083: Amanda (Backup services): amanda, kerberos'd aanda, amandaidx, amidxtape
Well-knowned UDP ports
53: DNS.
68: DHCP (Dynamic Host Configuration Protocol).
69: TFTP (Trivial FTP, mostly used for diskless workstations when obtaining their kernel).
111: portmapper.
161: SNMP (Simple Network Management Protocol).
4672: EMule UDP default.