DOCUMENT:Q136403 19-MAR-2002 [crossnet] TITLE :Description of UDP Ports PRODUCT :Windows for Workgroups and Windows NT Networking Issues PROD/VER::3.1,3.11,3.11a,3.11b,3.5,3.51 OPER/SYS: KEYWORDS: ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Windows NT Server versions 3.1, 3.5, 3.51 - Microsoft Windows NT Workstation versions 3.1, 3.5, 3.51 - Microsoft Windows NT Advanced Server, version 3.1 - Microsoft TCP/IP-32 for Windows for Workgroups, versions 3.11, 3.11a, 3.11b ------------------------------------------------------------------------------- SUMMARY ======= 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. MORE INFORMATION ================ 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: Port Keyword Description ---- ----------- ------------------------------ 15 NETSTAT What is the network status 53 DOMAIN Domain Name Server 69 TFTP Trivial File Transfer Protocol 137 NETBIOS-NS NetBIOS name service 138 NETBIOS-DGM NetBIOS datagram service 161 SNMP SNMP network monitor 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: Q120642 TCP/IP and NBT Configuration Parameters for Windows 2000 or Windows NT REFERENCES ========== "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. Additional query words: ppp endpoint connection ====================================================================== Keywords : Technology : kbWinNTsearch kbWinNTWsearch kbWinNT351search kbWinNT350search kbWinNTW350 kbWinNTW350search kbWinNTW351search kbWinNTW351 kbWinNTW310 kbWinNTSsearch kbWinNTS351 kbWinNTS350 kbWinNTS310 kbWinNTAdvSerSearch kbWinNTAdvServ310 kbWinNTS351search kbWinNTS350search kbWinNTS310search kbAudDeveloper kbWinNT310Search kbWinNTW310Search kbTCPIPSearch kbZNotKeyword3 kbTCPIP311 kbTCPIP311a kbTCPIP311b Version : :3.1,3.11,3.11a,3.11b,3.5,3.51 ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 2002.