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

Numbered 0 Through 1023

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Bradley Mitchell
Bradley Mitchell
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  • Massachusetts Institute of Technology
  • University of Illinois
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Updated on May 1, 2020

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. 

Internet protocols - illustration
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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.
  19. (TCP/UDP) Character Generator Protocol. See RFC 864.
  20. (TCP) File Transfer. For FTP data.
  21. (TCP) File Transfer. For FTP control.
  22. (TCP) SSH Remote Login Protocol. (UDP) pcAnywhere.
  23. (TCP) Telnet
  24. (TCP/UDP) For private mail systems.
  25. (TCP) Simple Mail Transfer Protocol (SMTP). See RFC 821.
  26. (TCP/UDP) Unassigned
  27. (TCP/UDP) ESMTP. POP mail service of SLMail.
  28. (TCP/UDP) Unassigned
  29. (TCP/UDP) MSG ICP.
  30. (TCP/UDP) Unassigned
  31. (TCP/UDP) MSG Authentication
  32. (TCP/UDP) Unassigned
  33. (TCP/UDP) Display Support Protocol
  34. (TCP/UDP) Unassigned
  35. (TCP/UDP) For private printer servers.
  36. (TCP/UDP) Unassigned
  37. (TCP/UDP) Time Protocol. See RFC 868.
  38. (TCP/UDP) Route Access Protocol (RAP). See RFC 1476.
  39. (UDP) Resource Location Protocol. See RFC 887.
  40. (TCP/UDP) Unassigned
  41. (TCP/UDP) Graphics
  42. (UDP) Host Name Server - Microsoft WINS
  43. (TCP) WHOIS. Also known as NICNAME. RFC 954.
  44. (TCP) MPM FLAGS Protocol
  45. (TCP) Message Processing Module (receive)
  46. (TCP) Message Processing Module (send)
  47. (TCP/UDP) NI FTP
  48. (TCP/UDP) Digital Audit Daemon
  49. (TCP) Login Host Protocol. Also known as TACACS. See RFC 927 and RFC 1492.
  50. (TCP/UDP) Remote Mail Checking Protocol (RMCP). See RFC 1339.
  51. (TCP/UDP) IMP Logical Address Maintenance
  52. (TCP/UDP) XNS Time Protocol
  53. (TCP/UDP) Domain Name Server (DNS)
  54. (TCP/UDP) XNS Clearinghouse
  55. (TCP/UDP) ISI Graphics Language
  56. (TCP/UDP) XNS Authentication
  57. (TCP/UDP) private terminal access. For example, TCP Mail Transfer Protocol (MTP). See RFC 772 and RFC 780.
  58. (TCP/UDP) XNS Mail
  59. (TCP/UDP) private file services. For example, NFILE. See RFC 1037.
  60. (TCP/UDP) Unassigned
  61. (TCP/UDP) NI Mail
  62. (TCP/UDP) ACA Services
  63. (TCP/UDP) Whois and Network Information Lookup Service. Also known as Whois++. See RFC 1834.
  64. (TCP/UDP) Communications Integrator
  65. (TCP/UDP) TACACS Database Service
  66. (TCP/UDP) Oracle SQL*NET
  67. (TCP/UDP) Bootstrap Protocol Server. (UDP) Unofficially, Dynamic Host Configuration Protocol (DHCP) servers use this port.
  68. (TCP/UDP) Bootstrap Protocol Client (BOOTP). See RFC 951. (UDP) Unofficially, DHCP clients use this port.
  69. (TCP/UDP) Trivial File Transfer Protocol (TFTP). See RFC 906 and RFC 1350.
  70. (TCP/UDP) Gopher. See RFC 1436.
  71. (TCP/UDP) Remote Job Service
  72. (TCP/UDP) Remote Job Service
  73. (TCP/UDP) Remote Job Service
  74. (TCP/UDP) Remote Job Service
  75. (TCP/UDP) private dial-out services
  76. (TCP/UDP) Distributed External Object Store
  77. (TCP/UDP) private remote job execution services
  78. (TCP/UDP) Vettcp Service
  79. (TCP/UDP) Finger User Information Protocol. See RFC 1288.
  80. (TCP) Hypertext Transfer Protocol (HTTP). See RFC 2616.
  81. (TCP/UDP) HOSTS2 Name Server
  82. (TCP/UDP) XFER Utility
  83. (TCP/UDP) MIT ML Device
  84. (TCP/UDP) Common Trace Facility
  85. (TCP/UDP) MIT ML Device
  86. (TCP/UDP) Micro Focus COBOL
  87. (TCP/UDP) private terminal links
  88. (TCP/UDP) Kerberos Network Authentication Service. See RFC 1510.
  89. (TCP/UDP) SU/MIT Telnet Gateway
  90. (TCP/UDP) DNSIX Security Attribute Token Map
  91. (TCP/UDP) MIT Dover Spooler
  92. (TCP/UDP) Network Printing Protocol
  93. (TCP/UDP) Device Control Protocol
  94. (TCP/UDP) Tivoli Object Dispatcher
  95. (TCP/UDP) SUPDUP Display Protocol. See RFC 734.
  96. (TCP/UDP) DIXIE Protocol. See RFC 1249.
  97. (TCP/UDP) Swift Remote Virtual File Protocol
  98. (TCP/UDP) TAC News. Unofficially used today by Linux utility linuxconf.
  99. (TCP/UDP) Metagram Relay
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