This is a list of Internet socket port numbers used by protocols of the Transport Layer of the Internet Protocol Suite for the establishment of host-to-host connectivity.

Originally, port numbers were used by the Network Control Program (NCP) which needed two ports for half duplex transmission. Later, the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP) needed only one port for bidirectional traffic (full duplex). The even numbered ports were not used, and this resulted in some even numbers in the well-known port number range being unassigned. The Stream Control Transmission Protocol (SCTP) and the Datagram Congestion Control Protocol (DCCP) also use port numbers. They usually use port numbers that match the services of the corresponding TCP or UDP implementation, if they exist.

Commonly used port numbers

Port Number


1 TCP Port Service Multiplexer (TCPMUX)
5 Remote Job Entry (RJE)
18 Message Send Protocol (MSP)
20 FTP -- Data
21 FTP -- Control
22 SSH Remote Login Protocol
23 Telnet
25 Simple Mail Transfer Protocol (SMTP)
37 Time
42 Host Name Server (Nameserv)
43 WhoIs
49 Login Host Protocol (Login)
53 Domain Name System (DNS)
69 Trivial File Transfer Protocol (TFTP)
70 Gopher Services
79 Finger
103 X.400 Standard
108 SNA Gateway Access Server
109 POP2
110 POP3
115 Simple File Transfer Protocol (SFTP)
118 SQL Services
119 Newsgroup (NNTP)
137 NetBIOS Name Service
139 NetBIOS Datagram Service
143 Interim Mail Access Protocol (IMAP)
150 NetBIOS Session Service
156 SQL Server
161 SNMP
179 Border Gateway Protocol (BGP)
190 Gateway Access Control Protocol (GACP)
194 Internet Relay Chat (IRC)
197 Directory Location Service (DLS)
389 Lightweight Directory Access Protocol (LDAP)
396 Novell Netware over IP
444 Simple Network Paging Protocol (SNPP)
445 Microsoft-DS
458 Apple QuickTime
546 DHCP Client
547 DHCP Server
569 MSN
1080 Socks

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