A Guide To Alternative Port Selection


A comprehensive listing by the Internet Assigned Numbers Authority can be found here. This is the official list. IANA is the organization that actually assigns these numbers, so this is really the place to look.

But the short story is, ports 49152 to 65535 are the ones to shoot for. They're known as Dynamic or Private Ports, and are there to use freely without stepping on any ports being used by your computer for other things.

Following is a list of the ports your machine might use at some time or another:

Ports below 1024 are called the "Well-Known Ports", used by various system processes. You can use any port within this range that are not in use, but unless you really know your computer, you can't be sure which ones are being used by your machine at any given time.

20 FTP data (File Transfer Protocol)
21 FTP (File Transfer Protocol)
22 SSH (Secure Shell)
23 Telnet
25 SMTP (Send Mail Transfer Protocol)
43 whois
53 DNS (Domain Name Service)
68 DHCP (Dynamic Host Control Protocol)
79 Finger
80 HTTP (HyperText Transfer Protocol)
110 POP3 (Post Office Protocol, version 3)
115 SFTP (Secure File Transfer Protocol)
119 NNTP (Network New Transfer Protocol)
123 NTP (Network Time Protocol)
137 NetBIOS-ns
138 NetBIOS-dgm
139 NetBIOS
143 IMAP (Internet Message Access Protocol)
161 SNMP (Simple Network Management Protocol)
194 IRC (Internet Relay Chat)
220 IMAP3 (Internet Message Access Protocol 3)
389 LDAP (Lightweight Directory Access Protocol)
443 SSL (Secure Socket Layer)
445 SMB (NetBIOS over TCP)
666 Doom
993 SIMAP (Secure Internet Message Access Protocol)
995 SPOP (Secure Post Office Protocol)

Ports between 1024 and 29151 are known as the Registered Ports. Basically, programs are supposed to register their use of these ports and thereby try to be careful and avoid stomping on each other. Here are some common ports and their programs. Same thing applies concerning ports within this range that aren't on this list -- you never know for sure which ones are being used.

(Edit by LOTR: Ports not to use: 7001 or 27016. These are used by hostile BOTs and are auto-blocked by both WireShare and Skulls GWebCache services. Do not use any port in the 270xx range.)

1243 SubSeven (Trojan - security risk!)
1352 Lotus Notes
1433 Microsoft SQL Server
1494 Citrix ICA Protocol
1521 Oracle SQL
1604 Citrix ICA / Microsoft Terminal Server
2049 NFS (Network File System)
3306 mySQL
4000 ICQ
5010 Yahoo! Messenger
5190 AOL Instant Messenger
5632 PCAnywhere
5800 VNC
5900 VNC
6000 X Windowing System
6699 Napster
6776 SubSeven (Trojan - security risk!)
7070 RealServer / QuickTime
7778 Unreal
8080 HTTP
26000 Quake
27010 Half-Life
27960 Quake III
31337 BackOrifice (Trojan - security risk!)



We all owe a large and extra warm thank you to Threadmaster,
moderator extraordinaire of the BearShare Forums, for helping to help here.

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