Description of UDP Ports

The User Datagram Protocol is an unreliable, connectionless oriented protocol that uses an IP address for the destination host and a port number to identify the destination application.

The UDP port number is distinct from any physical port on a computer such as a COM port or an I/O port address. The UDP port is a 16-bit address that exists only for the purpose of passing certain types of datagram information to the correct location above the transport layer of the protocol stack.

UDP ports are not the same as TCP ports, though TCP and UDP may use the same port number in certain instances. The UDP ports can receive more than one message at a time, and they are identified by "well known" port numbers. The following is a listing of some of the more common "well known" UDP ports:

The UDP specification is defined in RFC 768.

Note: The NETBIOS-NS (NetBIOS name service) port value can be configured to accommodate products from specific vendors. The Registry parameter that controls this value is NameServerPort.

For additional information on the NameServerPort parameter, please see the following article(s) in the Microsoft Knowledge Base:

"Inter-Networking with Microsoft TCP/IP Using Microsoft Windows NT, Participant's Workbook," P/N 4275A, Appendix A, page 222.

"TCP/IP Illustrated, Volume 1, The Protocols," W. Richard Stevens, pp 6,7,12,13, Addison-Wesley, 1994.