TCP RFCs

TCP, Transmission Control Protocol, is a networking protocol that enables connections between two machines on a network.

The Original RFCs

• RFC 793 — Transmission Control Protocol (September 1981)
• RFC 1122 — Requirements for Internet Hosts -- Communication Layers (October 1989)

Additional RFCs

• RFC 2001 — TCP Slow Start, Congestion Avoidance, Fast Retransmit, and Fast Recovery Algorithms (Obsolete) (January 1997)
• RFC 2018 — TCP Selective Acknowledgement Options (October 1996)
• RFC 2581 — TCP Congestion Control (Obsolete) (April 1999)
• RFC 3042 — Enhancing TCP's Loss Recovery Using Limited Transmit (January 2001)
• RFC 3390 — Increasing TCP's Initial Window (October 2002)
• RFC 4987 — TCP SYN Flooding Attacks and Common Mitigations (August 2007)
• RFC 5681 — TCP Congestion Control (September 2009)
• RFC 6093 — On the Implementation of the TCP Urgent Mechanism (January 2011)
• RFC 6298 — Computing TCP's Retransmission Timer (June 2011)
• RFC 6528 — Defending against Sequence Number Attacks (February 2012)
• RFC 6824 — TCP Extensions for Multipath Operation with Multiple Addresses (January 2013)
• RFC 7323 — TCP Extensions for High Performance (September 2014)
• RFC 7413 — TCP Fast Open (December 2014)
• RFC 7414 — A Roadmap for TCP Specification Documents (February 2015)

Historic Extensions

The extensions specified in RFC 1072, RFC 1106, RFC 1110, RFC 1145, RFC 1146, RFC 1379, RFC 1644, and RFC 1693 were all moved to Historic Status by RFC 6247, and some of the RFCs in the section above have older, obsolete versions.

• RFC 1072 — TCP Extensions for Long-Delay Paths (Obsolete) (October 1988)
• RFC 1106 — TCP Big Window and Nak Options (Obsolete) (June 1989)
• RFC 1110 — A Problem with the TCP Big Window Option (Obsolete) (August 1989)
• RFC 1145 — TCP Alternate Checksum Options (Obsolete) (February 1990)
• RFC 1146 — TCP Alternate Checksum Options (Obsolete) (February 1990)
• RFC 1323 — TCP Extensions for High Performance (Obsolete) (May 1992)
• RFC 1379 — Extending TCP for Transactions -- Concepts (Obsolete) (November 1992)
• RFC 1644 — T/TCP -- TCP Extensions for Transactions Functional Specification (Obsolete) (July 1994)
• RFC 1693 — An Extension to TCP : Partial Order Service (Obsolete) (November 1994)
• RFC 2988 — Computing TCP's Retransmission Timer (Obsolete) (November 2000)
• RFC 6247 — Moving the Undeployed TCP Extensions (listed above) to Historic Status (May 2011)

Port Numbers

IANA also maintains the list of assigned TCP and UDP port numbers, such as “Port 80” for HTTP.