List of TCP Ports and UDP Ports (Well-Known)

Numbered 0 Through 1023

Transmission Control Protocol (TCP) Header
Transmission Control Protocol (TCP) Header.

The Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) each use port numbers for their communication channels. The ports numbered 0 through 1023 are the well-known system ports, reserved for special uses. 

Port 0 is not used for TCP/UDP communication although it used as a network programming construct. The breakdown for other system ports is:

  1. (TCP) TCPMUX - TCP Port Service Multiplexer. Allows any of multiple TCP services to be contacted by their service name. See RFC 1078.
  1. (TCP) Management Utility. Formerly used by the Compressnet product, for compression of TCP WAN traffic.
  2. (TCP) Compression Process. Formerly used by Compressent for compression of TCP WAN traffic.
  3. (TCP/UDP) Unassigned
  4. (TCP/UDP) Remote Job Entry. Mechanism for executing batch jobs remotely. See RFC 407.
  5. (TCP/UDP) Unassigned
  6. (TCP/UDP) Echo. When enabled for debugging purposes, returns to the source any data received. See RFC 862.
  7. (TCP/UDP) Unassigned
  8. (TCP/UDP) Discard. When enabled for debugging purposes, throws away any data received with no response sent. See RFC 86.
  9. (TCP/UDP) Unassigned
  10. (TCP) Active Users. Unix TCP systat. See RFC 866.
  11. (TCP/UDP) Unassigned
  12. (TCP/UDP) Daytime. See RFC 867.
  13. (TCP/UDP) Unassigned
  14. (TCP/UDP) Unassigned. Formerly reserved for Unix netstat.
  15. (TCP/UDP) Unassigned.
  16. (TCP/UDP) Quote of the Day. For Unix qotd. See RFC 865.
  17. (TCP) Message Send Protocol (formerly) and Remote Write Protocol. (UDP) Remote Wire Protocol. See RFC 1312 and RFC 1756.
  1. (TCP/UDP) Character Generator Protocol. See RFC 864.
  2. (TCP) File Transfer. For FTP data.
  3. (TCP) File Transfer. For FTP control.
  4. (TCP) SSH Remote Login Protocol. (UDP) pcAnywhere.
  5. (TCP) Telnet
  6. (TCP/UDP) For private mail systems.
  7. (TCP) Simple Mail Transfer Protocol (SMTP). See RFC 821.
  8. (TCP/UDP) Unassigned
  9. (TCP/UDP) ESMTP. POP mail service of SLMail.
  1. (TCP/UDP) Unassigned
  3. (TCP/UDP) Unassigned
  4. (TCP/UDP) MSG Authentication
  5. (TCP/UDP) Unassigned
  6. (TCP/UDP) Display Support Protocol
  7. (TCP/UDP) Unassigned
  8. (TCP/UDP) For private printer servers.
  9. (TCP/UDP) Unassigned
  10. (TCP/UDP) Time Protocol. See RFC 868.
  11. (TCP/UDP) Route Access Protocol (RAP). See RFC 1476.
  12. (UDP) Resource Location Protocol. See RFC 887.
  13. (TCP/UDP) Unassigned
  14. (TCP/UDP) Graphics
  15. (UDP) Host Name Server - Microsoft WINS
  16. (TCP) WHOIS. Also known as NICNAME. RFC 954.
  17. (TCP) MPM FLAGS Protocol
  18. (TCP) Message Processing Module (receive)
  19. (TCP) Message Processing Module (send)
  20. (TCP/UDP) NI FTP
  21. (TCP/UDP) Digital Audit Daemon
  22. (TCP) Login Host Protocol. Also known as TACACS. See RFC 927 and RFC 1492.
  23. (TCP/UDP) Remote Mail Checking Protocol (RMCP). See RFC 1339.
  24. (TCP/UDP) IMP Logical Address Maintenance
  25. (TCP/UDP) XNS Time Protocol
  26. (TCP/UDP) Domain Name Server (DNS)
  27. (TCP/UDP) XNS Clearinghouse
  28. (TCP/UDP) ISI Graphics Language
  29. (TCP/UDP) XNS Authentication
  30. (TCP/UDP) private terminal access. For example, TCP Mail Transfer Protocol (MTP). See RFC 772 and RFC 780.
  31. (TCP/UDP) XNS Mail
  32. (TCP/UDP) private file services. For example, NFILE. See RFC 1037.
  33. (TCP/UDP) Unassigned
  34. (TCP/UDP) NI Mail
  1. (TCP/UDP) ACA Services
  2. (TCP/UDP) Whois and Network Information Lookup Service. Also known as Whois++. See RFC 1834.
  3. (TCP/UDP) Communications Integrator
  4. (TCP/UDP) TACACS Database Service
  5. (TCP/UDP) Oracle SQL*NET
  6. (TCP/UDP) Bootstrap Protocol Server. (UDP) Unofficially, Dynamic Host Configuration Protocol (DHCP) servers use this port.
  7. (TCP/UDP) Bootstrap Protocol Client (BOOTP). See RFC 951. (UDP) Unofficially, DHCP clients use this port.
  8. (TCP/UDP) Trivial File Transfer Protocol (TFTP). See RFC 906 and RFC 1350.
  9. (TCP/UDP) Gopher. See RFC 1436.
  10. (TCP/UDP) Remote Job Service
  11. (TCP/UDP) Remote Job Service
  12. (TCP/UDP) Remote Job Service
  13. (TCP/UDP) Remote Job Service
  14. (TCP/UDP) private dial-out services
  15. (TCP/UDP) Distributed External Object Store
  16. (TCP/UDP) private remote job execution services
  17. (TCP/UDP) Vettcp Service
  18. (TCP/UDP) Finger User Information Protocol. See RFC 1288.
  19. (TCP) Hypertext Transfer Protocol (HTTP). See RFC 2616.
  20. (TCP/UDP) HOSTS2 Name Server
  21. (TCP/UDP) XFER Utility
  22. (TCP/UDP) MIT ML Device
  23. (TCP/UDP) Common Trace Facility
  24. (TCP/UDP) MIT ML Device
  25. (TCP/UDP) Micro Focus COBOL
  26. (TCP/UDP) private terminal links
  27. (TCP/UDP) Kerberos Network Authentication Service. See RFC 1510.
  28. (TCP/UDP) SU/MIT Telnet Gateway
  29. (TCP/UDP) DNSIX Security Attribute Token Map
  30. (TCP/UDP) MIT Dover Spooler
  31. (TCP/UDP) Network Printing Protocol
  32. (TCP/UDP) Device Control Protocol
  33. (TCP/UDP) Tivoli Object Dispatcher
  34. (TCP/UDP) SUPDUP Display Protocol. See RFC 734.
  35. (TCP/UDP) DIXIE Protocol. See RFC 1249.
  36. (TCP/UDP) Swift Remote Virtual File Protocol
  37. (TCP/UDP) TAC News. Unofficially used today by Linux utility linuxconf.
  38. (TCP/UDP) Metagram Relay

For a breakdown of other system ports, see: 100-149, 150-199, 200-249, 700-799, 800-1023.


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