Definition: A port number represents an endpoint or "channel" for network communications. Port numbers allow different applications on the same computer to utilize network resources without interfering with each other.
|
Port numbers most commonly appear in network programming, particularly socket programming. Sometimes, though, port numbers are made visible to the casual user. For example, some Web sites a person visits on the Internet use a URL like the following:
http://www.mairie-metz.fr:8080/
In this example, the number 8080 refers to the port number used by the Web browser to connect to the Web server. Normally, a Web site uses port number 80 and this number need not be included with the URL (although it can be).
In IP networking, port numbers can theoretically range from 0 to 65535. Most popular network applications, though, use port numbers at the low end of the range (such as 80 for HTTP). The port number is included as a field within the header of each IP packet.
Note: The term port also refers to several other aspects of network technology. A port can refer to a physical connection point for peripheral devices such as serial, parallel, and USB ports. The term port also refers to certain Ethernet connection points, such as those on a hub, switch, or router.
Also Known As: port number, protocol number
Port Number - Related Resources
Introduction to Port Number Technology
An explanation of port numbers through analogies to telephones and television stations.TCP/UDP Port Number Reference
Links to definitive port number listings for both TCP and UDP services.Network Programming Resources
A starting point for learning more about networks from a programmer's perspective.
