Transmission Control Protocol (TCP) Parameters

Last Updated
2014-07-03
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Registries included below

TCP Option Kind Numbers

Registration Procedure(s)
IESG Approval or Standards Action
Reference
[RFC2780]
Note
The Transmission Control Protocol (TCP) has provision for optional
header fields identified by an option kind field.  Options 0 and 1 are
exactly one octet which is their kind field.  All other options have
their one octet kind field, followed by a one octet length field,
followed by length-2 octets of option data.

[*] It is only appropriate to use these values in explicitly-
    configured experiments; they MUST NOT be shipped as defaults in
    implementations.  See [RFC3692] for details.
    
[**] These values have been deployed in the Internet without proper
    IANA assignment. At some point, these numbers may be officially
    allocated for some new purpose. It is therefore strongly recommended
    that implementers migrate to mechanisms with IANA-assigned values to
    avoid potential issues with their systems or products at a later point.

[***] This value has been deployed on the Internet in ways that are 
    not compatible with the documented use in this IANA allocation. 

    
Available Formats

CSV
Kind Length Meaning Reference
0 - End of Option List [RFC793]
1 - No-Operation [RFC793]
2 4 Maximum Segment Size [RFC793]
3 3 Window Scale [RFC-ietf-tcpm-1323bis-21]
4 2 SACK Permitted [RFC2018]
5 N SACK [RFC2018]
6 6 Echo (obsoleted by option 8) [RFC1072][RFC6247]
7 6 Echo Reply (obsoleted by option 8) [RFC1072][RFC6247]
8 10 Timestamps [RFC-ietf-tcpm-1323bis-21]
9 2 Partial Order Connection Permitted (obsolete) [RFC1693][RFC6247]
10 3 Partial Order Service Profile (obsolete) [RFC1693][RFC6247]
11 CC (obsolete) [RFC1644][RFC6247]
12 CC.NEW (obsolete) [RFC1644][RFC6247]
13 CC.ECHO (obsolete) [RFC1644][RFC6247]
14 3 TCP Alternate Checksum Request (obsolete) [RFC1146][RFC6247]
15 N TCP Alternate Checksum Data (obsolete) [RFC1146][RFC6247]
16 Skeeter [Stev_Knowles]
17 Bubba [Stev_Knowles]
18 3 Trailer Checksum Option [Subbu_Subramaniam][Monroe_Bridges]
19 18 MD5 Signature Option (obsoleted by option 29) [RFC2385]
20 SCPS Capabilities [Keith_Scott]
21 Selective Negative Acknowledgements [Keith_Scott]
22 Record Boundaries [Keith_Scott]
23 Corruption experienced [Keith_Scott]
24 SNAP [Vladimir_Sukonnik]
25 Unassigned (released 2000-12-18)
26 TCP Compression Filter [Steve_Bellovin]
27 8 Quick-Start Response [RFC4782]
28 4 User Timeout Option (also, other known unauthorized use) [***][1] [RFC5482]
29 TCP Authentication Option (TCP-AO) [RFC5925]
30 N Multipath TCP (MPTCP) [RFC6824]
31 Reserved (known unauthorized use without proper IANA assignment) [**]
32 Reserved (known unauthorized use without proper IANA assignment) [**]
33 Reserved (known unauthorized use without proper IANA assignment) [**]
34-75 Reserved
69 Reserved (known unauthorized use without proper IANA assignment) [**]
70 Reserved (known unauthorized use without proper IANA assignment) [**]
71-75 Reserved
76 Reserved (known unauthorized use without proper IANA assignment) [**]
77 Reserved (known unauthorized use without proper IANA assignment) [**]
78 Reserved (known unauthorized use without proper IANA assignment) [**]
79-252 Reserved
253 N RFC3692-style Experiment 1 (also improperly used for shipping products) [*] [RFC4727]
254 N RFC3692-style Experiment 2 (also improperly used for shipping products) [*] [RFC4727]

TCP Alternate Checksum Numbers

Registration Procedure(s)
Not defined
Reference
[RFC1146]
Available Formats

CSV
Number Description Reference
0 TCP Checksum [RFC1146]
1 8-bit Fletchers's algorithm [RFC1146]
2 16-bit Fletchers's algorithm [RFC1146]
3 Redundant Checksum Avoidance [J_Kay]

Cryptographic Algorithms for TCP-AO Registration

Registration Procedure(s)
RFC Publication After Expert Review
Reference
[RFC5926]
Available Formats

CSV
Algorithm Reference
SHA1 [RFC5926]
AES128 [RFC5926]

MPTCP Option Subtypes

Registration Procedure(s)
Standards Action
Reference
[RFC6824]
Available Formats

CSV
Value Symbol Name Reference
0x0 MP_CAPABLE Multipath Capable [RFC6824], Section 3.1
0x1 MP_JOIN Join Connection [RFC6824], Section 3.2
0x2 DSS Data Sequence Signal (Data ACK and Data Sequence Mapping) [RFC6824], Section 3.3
0x3 ADD_ADDR Add Address [RFC6824], Section 3.4.1
0x4 REMOVE_ADDR Remove Address [RFC6824], Section 3.4.2
0x5 MP_PRIO Change Subflow Priority [RFC6824], Section 3.3.8
0x6 MP_FAIL Fallback [RFC6824], Section 3.6
0x7 MP_FASTCLOSE Fast Close [RFC6824], Section 3.5
0x8-0xe Unassigned
0xf Reserved for Private Use [RFC6824]

MPTCP Handshake Algorithms

Registration Procedure(s)
Standards Action
Reference
[RFC6824]
Available Formats

CSV
Flag Bit Meaning Reference
A Checksum required [RFC6824], Section 3.1
B Extensibility [RFC6824], Section 3.2
C-G Unassigned
H HMAC-SHA1 [RFC6824], Section 3.2

TCP Experimental Option Experiment Identifiers (TCP ExIDs)

Registration Procedure(s)
First Come First Served
Reference
[RFC6994]
Note
IANA will record known duplicate uses.
Available Formats

CSV
Value Description Reference
0x0348 Host ID [draft-williams-exp-tcp-host-id-opt]
0x5323 Service Number [draft-touch-tcpm-sno]
0x75EC FFEE Timestamp Interval [draft-trammell-tcpm-timestamp-interval]
0xE2D4 C3D9 Shared Memory communications over RMDA protocol [draft-fox-tcpm-shared-memory-rdma]
0xF989 Fast Open [draft-ietf-tcpm-fastopen]

People

ID Name Contact URI Last Updated
[J_Kay] J. Kay mailto:jkay&ucsd.edu 1994-09
[Keith_Scott] Keith Scott mailto:kscott&mitre.org 1999-02
[Monroe_Bridges] Monroe Bridges mailto:monroe&cup.hp.com 1994-09
[Stev_Knowles] Stev Knowles mailto:stev&ftp.com 1995-03
[Steve_Bellovin] Steve Bellovin mailto:smb&research.att.com 2000-03
[Subbu_Subramaniam] Subbu Subramaniam mailto:subbu&cup.hp.com 1994-09
[Vladimir_Sukonnik] Vladimir Sukonnik mailto:vladimir&sitaranetworks.com 1999-02

Footnote

[1]
[https://devcentral.f5.com/tech-tips/articles/accessing-tcp-options-from-irules]