Administrator's Guide

Appendix C. Lists of Reserved Ports,
ICMP Types and Codes, and Internet
Protocols
The following lists discuss the most important ports and the server services that belong to
them, and the different types of ICMP messages. Client programs usually use ports between
1024 and 65535.
There are also lists over Internet protocols, reserved IP addresses and a mapping between
netmasks and IP address intervals.
List of the most important reserved ports
This is a list of important ports. See /etc/services and http://www.iana.org/.
Name Port/protocol Description
echo 7/tcp
echo 7/udp
discard 9/tcp sink null
discard 9/udp sink null
systat 11/tcp users
daytime 13/tcp
daytime 13/udp
netstat 15/tcp
qotd 17/tcp quote
chargen 19/tcp ttytst source
chargen 19/udp ttytst source
ftp-data 20/tcp ftp data transfer
ftp 21/tcp ftp command
ssh 22/tcp Secure Shell
telnet 23/tcp
smtp 25/tcp mail
time 37/tcp timeserver
time 37/udp timeserver
rlp 39/udp resource location
nicname 43/tcp who is
domain 53/tcp domain name server
domain 53/udp domain name server
sql*net 66/tcp Oracle SQL*net
sql*net 66/udp Oracle SQL*net
bootps 67/tcp bootp server
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