UDP and TCP ports: A list of the most important ports

TCP and UDP are used to connect two devices over the Internet or other networks. However, to give data packages an entrance to the PC or server at the other end of the connection, the “doors” have to be open. These openings into the system are called ports. For both protocols, there are some known and important ports which you need to know when developing web apps.

What do ports do?

When communicating via the Internet, the two protocols TCP and UDP establish the connection, compile data packages again after transfer, and then hand them over to the programs addressed on the recipient’s device. For this handover to work, the operating system must create entrances and open them for the transfer. Every entrance has a specific code number. After the transfer, the receiving system knows where the data has to be delivered based on the port number. The data package always includes two port numbers: the sender’s and the recipient’s.

Ports have consecutive numbers – from 0 to 65536. Some of these code numbers are standardised, which means they are assigned to specific applications. These standard ports are also called well-known ports, as the code numbers are known to all and permanently assigned. There are also registered ports, which organisations or software producers have registered for their applications. The Internet Assigned Numbers Authority (IANA) is responsible for registration. There is also a wide range of port numbers that are assigned dynamically. For example, browsers use these ports when visiting a website. The number is then free again afterwards.

List of the most important ports

Among the over 65,000 ports, there are few code numbers that are essential for Internet communication. We want to show you the most important well-known ports and registered ports. Some of these ports are only authorised for one of the two protocols (TCP or UDP). There are also ports that were not officially registered for the service in question, but have established themselves unofficially. Some ports have double assignments.

Well-known ports

Port TCP UDP Name Description
1 tcpmux TCP port multiplexer
5 rje Remote job entry
7 echo Echo service
9 discard Zero service for test purposes
11 systat System information
13 daytime Time and date
17 qotd Sends quote of the day
18 msp Sends text messages
19 chargen Sends an infinite character string
20   ftp-data FTP data transfer
21 ftp FTP connection
22 ssh Secure Shell Service
23   telnet Telnet service
25   smtp Simple Mail Transfer Protocol
37 time Machine-readable time protocol
39 rlp Resource location protocol
42 nameserver Name service
43   nicname WHOIS directory service
49 tacacs Terminal access controller access control system
50 re-mail-ck Remote mail checking
53 domain DNS name resolver
67   bootps Bootstrap protocol services
68   bootpc Bootstrap client
69   tftp Trivial file transfer protocol
70   gopher Document search
71   genius Genius protocol
79   finger Delivers user contact information
80   http Hypertext transfer protocol
81     Torpark: Onion routing (unofficial)
82     Torpark: Control (unofficial)
88 kerberos Network authentication system
101   hostname NIC host name
102   Iso-tsap ISO TSAP protocol
105 csnet-ns Mailbox mail server
107   rtelnet Remote telnet
109   pop2 Post office protocol v2 for e-mail communication
110   pop3 Post office protocol v3 for e-mail communication
111 sunrpc RPC protocol for NFS
113   auth Authentication service
115   sftp Simple file transfer protocol
117   uucp-path File transfer between Unix systems
119   nntp Transfer of messages in news groups
123   ntp Time synchronisation service
137 netbios-ns NETBIOS name service
138 netbios-dgm NETBIOS datagram service
139 netbios-ssn NETBIOS session service
143 imap Internet message access protocol for e-mail communication
161   snmp Simple network management protocol
162 snmptrap Simple network management protocol trap
177 xdmcp X display manager
179   bgp Border gateway protocol
194 irc Internet relay chat
199 smux SNMP UNIX multiplexer
201 at-rtmp AppleTalk routing
209 qmtp Quick mail transfer protocol
210 z39.50 Bibliographic information system
213 ipx Internetwork packet exchange
220 imap3 IMAP v3 for e-mail communication
369 rpc2portmap Coda file system port mapper
370 codaauth2 Coda file system authentication service
389 ldap Lightweight directory access protocol
427 svrloc Service location protocol
443   https HTTPS (HTTP over SSL/TLS)
444 snpp Simple network paging protocol
445   microsoft-ds SMB over TCP/IP
464 kpasswd Kerberos password change
500   isakmp Security protocol
512   exec Remote process execution
512   comsat/biff Mail client and server
513   login Login to remote computer
513   who Whod user logging daemon
514   shell Remote shell
514   syslog Unix system logging service
515   printer Line printer daemon print services
517   talk Talk remote calling
518   ntalk Network talk
520   efs Extended file name server
520   router Routing information protocol
521   ripng Routing information protocol for IPv6
525   timed Time server
530 courier Courier remote procedure call
531 conference Chat over AIM and IRC
532   netnews Netnews newsgroup service
533   netwall Emergency broadcasts
540   uucp Unix-to-Unix copy protocol
543   klogin Kerberos v5 remote login
544   kshell Kerberos v5 remote shell
546 dhcpv6-client DHCP v6 client
547 dhcpv6-server DHCP v6 server
548   afpovertcp Apple filing protocol over TCP
554 rtsp Real time streaming protocol
556   remotefs Remote file system
563 nntps NNTP over SSL/TLS
587   submission Message submission agent
631 ipp Internet printing protocol
631   Common Unix printing system (unofficial)
636 ldaps LDAP over SSL/TLS
674   acap Application configuration access protocol
694 ha-cluster Heartbeat service
749 kerberos-adm Kerberos v5 administration
750   kerberos-iv Kerberos v4 services
873   rsync rsync file transfer services
992 telnets Telnet over SSL/TLS
993   imaps IMAP over SSL/TLS
995   pop3s POP3 over SSL/TLS

Registered ports

Port TCP UDP Name Description
1080   socks SOCKS proxy
1433   ms-sql-s Microsoft SQL server
1434 ms-sql-m Microsoft SQL monitor
1494   ica Citrix ICA client
1512 wins Windows internet name service
1524 ingreslock Ingres DBMS
1701   l2tp Layer 2 tunnelling protocol/Layer 2 forwarding
1719   h323gatestat H.323
1720   h323hostcall H.323
1812 radius RADIUS authentication
1813 radius-acct RADIUS access
1985   hsrp Cisco HSRP
2008     Teamspeak 3 accounting (unofficial)
2010     Teamspeak 3 web list (unofficial)
2049 nfs Network file system
2102 zephyr-srv Zephyr server
2103 zephyr-clt Zephyr client
2104 zephyr-hm Zephyr host manager
2401   cvspserver Concurrent versions system
2809 corbaloc Common object request broker architecture
3306 mysql MySQL database service (also for MariaDB)
4321   rwhois Remote whois service
5999   cvsup CVSup
6000   X11 X Windows system services
11371   pgpkeyserver Public keyserver for PGP
13720 bprd Symantec/Veritas NetBackup
13721 bpdbm Symantec/Veritas database manager
13724 vnetd Symantec/Veritas network utility
13782 bpcd Symantec/Veritas NetBackup
13783 vopied Symantec/Veritas VOPIE
22273 wnn6 Kana/Kanji conversion
23399       Skype (unofficial)
25565     Minecraft
26000 quake Quake and other multiplayer games
27017       MongoDB
33434 traceroute Network tracking

Ports numbered 49152 and higher are dynamic ports. They are not assigned by IANA. Any application can use these ports locally or globally in a dynamic way. As a result, it could easily be the case that one of these ports is already occupied.

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