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Network Working Group                                         C. Bormann
Internet-Draft                                    Universität Bremen TZI
Intended status: Informational                             27 March 2020
Expires: 28 September 2020


     impl-info: A link relation type for disclosing implementation
                              information
                    draft-bormann-t2trg-rel-impl-01

Abstract

   For debugging, it is often helpful to have information about the
   implementation of a peer.  The present specification defines a link
   relation type, "impl-info", that can be used to convey such
   information via self-description, such as in the "/.well-known/core"
   resource.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 28 September 2020.

Copyright Notice

   Copyright (c) 2020 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 (https://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.  Code Components
   extracted from this document must include Simplified BSD License text
   as described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Simplified BSD License.



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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   2
   3.  Security considerations . . . . . . . . . . . . . . . . . . .   2
   4.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   3
     4.1.  Normative References  . . . . . . . . . . . . . . . . . .   3
     4.2.  Informative References  . . . . . . . . . . . . . . . . .   3
   Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . .   4
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   4

1.  Introduction

   When debugging an interoperability problem, it is often helpful to
   have information about the implementation version of a peer.  To
   enable the disclosure of such information, HTTP defines header fields
   such as Server and User-Agent [RFC7231].

   In CoAP [RFC7252], it is rarely appropriate to send information of
   this kind in every request or response.  Instead, the present
   specification defines a link relation type, "impl-info", that can be
   used to convey this information via the self-description capabilities
   of the /.well-known/core resource [RFC6690] and the CoRE resource
   directory [I-D.ietf-core-resource-directory].

2.  IANA Considerations

   This specification requests the registration of the link relation
   type "impl-info".

   The registration template as per [RFC8288] follows.

   *  _Relation Name_: "impl-info"

   *  _Description_: Refers to implementation information that may be
      helpful in diagnosing technical problems with the implementation
      of the context, such as lists of components and their
      implementation versions.

   *  _Reference_: [THIS]

3.  Security considerations

   The security considerations listed in Section 9.6 of [RFC7231] and
   the sections referenced there apply.

   The security considerations listed in Section 11.3 of [RFC7252]
   apply.  As adding another link to "/.well-known/core" does increase



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   the size of a response to a GET request for that resource, the
   mitigation mentioned in that section to limit the amplification
   factor becomes even more important.

   Disclosing information about an implementation can make it easier for
   an attacker to select an attack, or to build automated tools that
   search for promising victims.  Fingerprinting techniques can provide
   information to attackers that is usable in the same way, so adding
   information via self-description may or may not actually exacerbate
   this problem.

4.  References

4.1.  Normative References

   [RFC8288]  Nottingham, M., "Web Linking", RFC 8288,
              DOI 10.17487/RFC8288, October 2017,
              <https://www.rfc-editor.org/info/rfc8288>.

   [THIS]     Bormann, C., "impl-info: A link relation type for
              disclosing implementation information", Work in Progress,
              Internet-Draft, draft-bormann-t2trg-rel-impl-00, 28
              January 2018, <http://www.ietf.org/internet-drafts/draft-
              bormann-t2trg-rel-impl-00.txt>.

4.2.  Informative References

   [I-D.ietf-core-resource-directory]
              Shelby, Z., Koster, M., Bormann, C., Stok, P., and C.
              Amsuess, "CoRE Resource Directory", Work in Progress,
              Internet-Draft, draft-ietf-core-resource-directory-24, 9
              March 2020, <http://www.ietf.org/internet-drafts/draft-
              ietf-core-resource-directory-24.txt>.

   [RFC6690]  Shelby, Z., "Constrained RESTful Environments (CoRE) Link
              Format", RFC 6690, DOI 10.17487/RFC6690, August 2012,
              <https://www.rfc-editor.org/info/rfc6690>.

   [RFC7231]  Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
              Protocol (HTTP/1.1): Semantics and Content", RFC 7231,
              DOI 10.17487/RFC7231, June 2014,
              <https://www.rfc-editor.org/info/rfc7231>.

   [RFC7252]  Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
              Application Protocol (CoAP)", RFC 7252,
              DOI 10.17487/RFC7252, June 2014,
              <https://www.rfc-editor.org/info/rfc7252>.




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Acknowledgements

   The need for implementation information in the CoRE resource
   directory has been identified by Peter van der Stok.  Discussions
   with Peter and with Christian Amsüss (U+0043 U+0068 U+0072 U+0069
   U+0073 U+0074 U+0069 U+0061 U+006E U+0020 U+0041 U+006D U+0073 U+00FC
   U+0073 U+0073) led to the present proposal of employing self-
   description for this purpose.

Author's Address

   Carsten Bormann
   Universität Bremen TZI
   Postfach 330440
   D-28359 Bremen
   Germany

   Phone: +49-421-218-63921
   Email: cabo@tzi.org
































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