Cisco Catalyst 2000 Configuration Handbook page 306

Both UDP and TCP port numbers are divided into the following ranges:
■ Well-known port numbers (0 through 1023)
■ Registered port numbers (1024 through 49151)
■ Dynamic or private port numbers (49152 through 65535)
Usually, a port assignment uses a common port number for both UDP and TCP. A con-
nection from a client to a server uses the well-known port on the server as a service con-
tact port, whereas the client is free to dynamically assign its own port number. For TCP,
the connection is identified by the source and destination IP addresses, as well as the
source and destination TCP port numbers.
Well-known or assigned IP protocols are registered with the IANA. The information pre-
sented here is reproduced with permission from the IANA. For the most current
IP protocol number assignment information, refer to www.iana.org/numbers.htm
under the "Port Numbers" link.
Table B-3 shows some commonly used protocols, their port numbers, and a brief descrip-
tion. The IANA has recorded around 3350 unique port numbers. Because of space limita-
tions, only a small subset of these port numbers are presented here.
Table B-3 Commonly Used Protocols and Associated Port Numbers
Keyword
echo
discard
systat
daytime
qotd
chargen
ftp-data
ftp
ssh
telnet
Any private mail system
smtp
msg-icp
msg-auth
Any private printer server
Appendix B: Well-known Protocol, Port, and Other Numbers 285
Description
Echo
Discard
Active Users
Daytime (RFC 867)
Quote of the Day
Character Generator
File Transfer [Default Data]
File Transfer [Control]
SSH Remote Login Protocol
Telnet
Any private mail system
Simple Mail Transfer
MSG ICP
MSG Authentication
Any private printer server
UDP/TCP
Port
7
9
11
13
17
19
20
21
22
23
24
25
29
31
35