An Experimental TCP Option for Host Identification
RFC 7974

Document Type RFC - Experimental (October 2016; No errata)
Last updated 2016-10-19
Stream ISE
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Stream ISE state Published RFC
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Shepherd write-up Show (last changed 2015-05-04)
IESG IESG state RFC 7974 (Experimental)
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IANA IANA review state Version Changed - Review Needed
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Independent Submission                                       B. Williams
Request for Comments: 7974                                  Akamai, Inc.
Category: Informational                                     M. Boucadair
ISSN: 2070-1721                                                   Orange
                                                                 D. Wing
                                                            October 2016

           An Experimental TCP Option for Host Identification

Abstract

   Recent RFCs have discussed issues with host identification in IP
   address-sharing systems, such as address/prefix-sharing devices and
   application-layer proxies.  Potential solutions for revealing a host
   identifier in shared address deployments have also been discussed.
   This memo describes the design, deployment, and privacy
   considerations for one such solution in operational use on the
   Internet today that uses a TCP option to transmit a host identifier.

Independent Submissions Editor Note

   This Informational document specifies an experimental TCP HOST_ID
   option that is already fairly widely deployed.  It discusses that
   option's privacy considerations in considerable detail and highlights
   the care providers need to exercise in any actual deployment.  The
   Independent Submissions Editor has chosen to publish this document in
   the Independent Stream so that potential deployers and implementors
   can understand all its details, so as to produce implementations that
   will interwork properly with other (existing) deployments.

IESG Note

   This proposal was previously proposed for adoption by the TCPM
   working group and rejected as being an undesirable technical design
   for both transport and privacy reasons.  This document specifies a
   new TCP option that uses the shared experimental options format.  The
   use of experimental TCP options is specified in [RFC6994] for TCP
   options "that are not yet eligible for assigned codepoints".  As this
   proposal has been rejected by the IETF community, it is not eligible
   for the registration of a TCP option codepoint.  It should be further
   noted that for experimental TCP options, it "is only appropriate to
   use these values in explicitly-configured experiments; they MUST NOT
   be shipped as defaults in implementations" [RFC4727].  The IESG also
   carried out a review as described in [RFC5742] and concluded that
   this proposal violates IETF principles expressed in [RFC7258] about
   pervasive monitoring as an attack and should therefore not be
   published without IETF review and IESG approval.  (The process

Williams, et al.              Informational                     [Page 1]
RFC 7974             Experimental TCP HOST_ID Option        October 2016

   described in [RFC5742] nonetheless allows the Independent Submissions
   Editor to publish, as has been chosen in this case.)  Deployments of
   this proprietary TCP option may be widely viewed as undermining
   privacy and are likely to encounter issues with reliability of
   transport.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This is a contribution to the RFC Series, independently of any other
   RFC stream.  The RFC Editor has chosen to publish this document at
   its discretion and makes no statement about its value for
   implementation or deployment.  Documents approved for publication by
   the RFC Editor are not a candidate for any level of Internet
   Standard; see Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7974.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.

Williams, et al.              Informational                     [Page 2]
RFC 7974             Experimental TCP HOST_ID Option        October 2016

Table of Contents

   1. Introduction ....................................................4
      1.1. Important Use Cases ........................................4
      1.2. Document Goals .............................................6
   2. Terminology .....................................................6
   3. Option Format ...................................................7
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