TCP and UDP Port Assignments
Transport Control Protocol (TCP), User Datagram Protocol (UDP) ports, and Protocol Numbers are important to TCP/IP networking, intranets, and the Internet. Ports and protocol numbers provide access to a host computer. However, they also create a security hazard by allowing uninvited access. Therefore, knowing which port to allow or disable increases a network's security. If the wrong ports or protocol numbers are disabled on a firewall, router, or proxy server as a security measure, essential services might become unavailable.
In This Appendix
Related Information in the Resource Kit
For a complete listing of Well-Known Ports, Registered ports, and protocol numbers, see the Port Assignments link on the Web Resources page at http://windows.microsoft.com/windows2000/reskit/webresources .