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

Numbered 0 Through 1023

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 of Other System Ports

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

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