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This is a list of TCP and UDP port numbers used by protocols for the operation of network applications.
The Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) only need one port for duplex, bidirectional traffic. They usually use port numbers that match the services of the corresponding TCP or UDP implementation, if they exist.
The Internet Assigned Numbers Authority (IANA) is responsible for maintaining the official assignments of port numbers for specific uses. 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.
|Yes||Described protocol is assigned for this port by IANA and is standardized, specified, or widely used for such.|
|Unofficial||Described protocol is not assigned for this port by IANA but is standardized, specified, or widely used for such.|
|Assigned||Described protocol is assigned by IANA for this port, but is not standardized, specified, or widely used for such.|
|No||Described protocol is not assigned by IANA, standardized, specified, or widely used for the port.|
|Reserved||Port is reserved by IANA, generally to prevent collision having its previous use removed. The port number may be available for assignment upon request to IANA.|
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 210 − 1) are the well-known ports or system ports. They are used by system processes that provide widely used types of network services. 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.
|0||N/A||N/A||N/A||N/A||In programming APIs (not in communication between hosts), requests a system-allocated (dynamic) port|
|1||Yes||Assigned||TCP Port Service Multiplexer (TCPMUX). Historic. Both TCP and UDP have been assigned to TCPMUX by IANA, but by design only TCP is specified.|
|5||Assigned||Assigned||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.|
|11||Yes||Yes||Active Users (systat service)|
|15||Unofficial||No||Previously netstat service|
|17||Yes||Yes||Quote of the Day (QOTD)|
|18||Yes||Yes||Message Send Protocol|
|19||Yes||Yes||Character Generator Protocol (CHARGEN)|
|23||Yes||Assigned||Telnet protocol - unencrypted text communications|
|25||Yes||Assigned||Simple Mail Transfer Protocol (SMTP), used for email routing between mail servers. Create mail server monitor|