For TCP and UDP, a port number is a 16-bit unsigned integer, thus ranging from 0 to 65535. For TCP, port number 0 is reserved and cannot be used, while for UDP, the source port is optional and a value of zero … See more

Transport-layer protocols, such as the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP), transfer data using protocol data units (PDUs). For TCP, … See more

An example of the use of ports is the delivery of email. A server used for sending and receiving email generally needs two services. The first service is used to transport email to and from other servers. This is accomplished with the Simple Mail Transfer … See more

The concept of port numbers was established by the early developers of the ARPANET in informal cooperation of software authors and system administrators. The … See more

The practice of attempting to connect to a range of ports in sequence on a single host is commonly known as port scanning. This is usually associated either with malicious See more

Port numbers are sometimes seen in web or other uniform resource locators (URLs). By default, HTTP uses port 80 and HTTPS uses port 443, but a URL like http://www.example.com:8080/path/ specifies that the web browser connects instead to port … See more