
However, many unofficial uses of both well-known and registered port numbers occur in practice. Similarly, many of the official assignments refer to protocols that were never or are no longer in common use. This article lists port numbers and their associated protocols that have experienced significant uptake. This is a dynamic list and may never be able to satisfy particular standards for completeness. You can help by adding missing items with reliable sources.

The port numbers in the range from 0 to 1023 (0 to 2 10 − 1) are the well-known ports or system ports.

They are used by system processes that provide widely used types of network services.


In programming APIs (not in communication between hosts), requests a system-allocated (dynamic) port On Unix-like operating systems, a process must execute with superuser privileges to be able to bind a network socket to an IP address using one of the well-known ports. Remote Job Entry was historically using socket 5 in its old socket form, while MIB PIM has identified it as TCP/5 and IANA has assigned both TCP and UDP 5 to it.Ĭharacter Generator Protocol (CHARGEN) įile Transfer Protocol (FTP) data transfer įile Transfer Protocol (FTP) control (command) Both TCP and UDP have been assigned to TCPMUX by IANA, but by design only TCP is specified.
