Ethernet Networking for the Small Office and Professional Home Office

B

TCP and UDP Ports

WelI-Known Ports

Software ports are used by TCP/IP to associate segments with application programs running on a host that receives a message. The well-known ports are used primarily by communications processes and other privileged applications, and have numbers between 0 and 1023.

Note: Application developers can register ports for their programs with IANA. Registered ports are in the range of 1024 through 49151. Ports between 49152 and 65536 are dynamic and/or private.

Table B-1 contains a selection of well-known ports that you may want your firewall to block. In almost all cases, both TCP and UDP have the same port number assignments.

Table B-1

Weil-Known TCP and UDP Ports

Port	Protocol or Application
1	TCP Port ...