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Ports
What is a port? Well, a port is used by TCP (Transmission Control
Protocol) to provide a connection for commonly occurring or standard traffic. An example
would be e-mail.
Before I explain this and show you how it works, I want to make clear that these port
numbers are not carved in stone. If you have a fairly configurable piece of software, you
can change these port numbers to anything you want. For purposes of explanation, I will be
using the default/common port numbers.
You open up your e-mail program and check your mail (Ok, another explanation. There are a
few ways you can check your e-mail. Some examples are POP, Kerberos and IMAP. They vary in
degrees of security for the authentication procedure and options that the server will
allow you to use to control your e-mail. For now, I'm just going to stick with straight
POP3 ident and auth.) Ok, where were we? Oh yeah, you open up your e-mail and check for
new mail. Well, you use port 113 to do the identification and authorization for your
account info and password, you receive your e-mail on port 110, and you send your outgoing
mail on port 25.
Why all the different ports? Well, they mainly serve to help sort out all the traffic
coming into/out of your computer. If you're anything like me, I download files, browse
internet sites (I really dislike the term "Surfing the Net"), chat in ICQ, and
upload files to my web page server, all at the same time. That's a lot of data to keep
track of. Ports help to keep all that data separate and going to the right places.
I've listed below some standard port numbers for the common types of activities. In
addition to the basic usage ports which are numbered 0 - 1023 called Well Known Ports
(BTW, these are assigned by IANA (Internet Assigned Numbers Authority)), there are two
more categories of ports. Registered Ports which are 1024 - 49151, and Dynamic/Private
Ports numbered 49152 - 65535.
| Name |
# |
Function |
ftp-data
ftp
telnet
smtp
domain
whois++
gopher
finger
http
kerberos
pop2
pop3
ident
auth
sftp
nntp
ntp
imap
irc
qmtp
softpc
imap3
openport
ldap
genie
imsp
infoseek
snpp
appleqtc
ph
mynet
who
irc-serv
klogin
whoami
eudora-set
doom
kerberos-adm |
20
21
23
25
53
63
70
79
80
88
109
110
113
113
115
119
123
143
194
209
215
220
260
389
402
406
414
444
458
481
511
513
529
543
565
592
666
749 |
File Transfer [Default Data]
File Transfer [Control]
Telnet
Simple Mail Transfer Protocol
Domain Name Server
whois++
Gopher
Finger
WWW/http (Internet connection)Post Office Protocol 2
Post Office Protocol 3
Simple File Transfer Protocol
Network News Transfer Protocol
Network Time Protocol
Internet Message Access Protocol
Internet Relay Chat
Quick Mail Transfer Protocol
Insignia Solutions
Internet Mil Access Protocol 3
Openport
Lightweight Directory Access Protocol
Interactive Mail Support Protocol
Simple Network Paging Protocol
Apple Quick time
mynet-as
Who is logged on
Doom Id software
kerberos administration |
