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Versions: 02 03 04 05 06 07 RFC 7043

Network Working Group                                           J. Abley
Internet-Draft                                  TekSavvy Solutions, Inc.
Intended status: Informational                           August 15, 2013
Expires: February 16, 2014


      Resource Records for EUI-48 and EUI-64 Addresses in the DNS
               draft-jabley-dnsext-eui48-eui64-rrtypes-07

Abstract

   48-bit Extended Unique Identifiers (EUI-48) and 64-bit Extended
   Unique Identifiers (EUI-64) are address formats specified by the IEEE
   for use in various layer-2 networks, e.g.  Ethernet.

   This document describes two new DNS resource record types, EUI48 and
   EUI64, for encoding Ethernet addresses in the DNS.

   This document describes potentially severe privacy implications
   resulting from indiscriminate publication of link-layer addresses in
   the DNS.  EUI-48 or EUI-64 addresses SHOULD NOT be published in the
   public DNS.  This document specifies an interoperable encoding of
   these address types for use in private DNS namespaces, where the
   privacy concerns can be constrained and mitigated.

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 http://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 February 16, 2014.

Copyright Notice

   Copyright (c) 2013 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



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   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
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   described in the Simplified BSD License.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  The EUI48 Resource Record  . . . . . . . . . . . . . . . . . .  5
     3.1.  EUI48 RDATA Wire Format  . . . . . . . . . . . . . . . . .  5
     3.2.  EUI48 RR Presentation Format . . . . . . . . . . . . . . .  5
     3.3.  Example  . . . . . . . . . . . . . . . . . . . . . . . . .  5
   4.  The EUI64 Resource Record  . . . . . . . . . . . . . . . . . .  6
     4.1.  EUI64 RDATA Wire Format  . . . . . . . . . . . . . . . . .  6
     4.2.  EUI64 RR Presentation Format . . . . . . . . . . . . . . .  6
     4.3.  Example  . . . . . . . . . . . . . . . . . . . . . . . . .  6
   5.  Example Use-Case: IP Address Tracking in DOCSIS Networks . . .  7
   6.  DNS Protocol Considerations  . . . . . . . . . . . . . . . . .  8
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  9
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . . 10
   9.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
     10.1. Normative References . . . . . . . . . . . . . . . . . . . 12
     10.2. Informative References . . . . . . . . . . . . . . . . . . 12
     10.3. Informative References . . . . . . . . . . . . . . . . . . 12
   Appendix A.  Editorial Notes . . . . . . . . . . . . . . . . . . . 13
     A.1.  RRType Parameter Allocation Template . . . . . . . . . . . 13
     A.2.  Change History . . . . . . . . . . . . . . . . . . . . . . 14
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 16
















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1.  Introduction

   The Domain Name System (DNS) is described in [RFC1034] and [RFC1035].
   This base specification defines many Resource Record Types (RRTypes),
   and subsequent specifications have defined others.  Each defined
   RRType provides a means of encoding particular data in the DNS.

   48-bit Extended Unique Identifiers (EUI-48) [EUI48] and 64-bit
   Extended Unique Identifiers (EUI-64) [EUI64] are address formats
   specified by the IEEE for use in various layer-2 networks, e.g.
   Ethernet.

   This document defines two new RRTypes, EUI48 and EUI64 for encoding
   EUI-48 and EUI-64 addresses in the DNS.

   There are potentially severe privacy implications resulting from the
   indiscriminate publication of link-layer addresses in the DNS (see
   Section 8).  This document recommends that EUI-48 or EUI-64 addresses
   SHOULD NOT be published in the public DNS.  This document specifies
   an interoperable encoding of these address types for use in private
   DNS namespaces, where the privacy implications can be constrained and
   mitigated.





























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2.  Terminology

   This document uses capitalised keywords such as MUST and MAY to
   describe the requirements for using the registered RRTypes.  The
   intended meaning of those keywords in this document are the same as
   those described in [RFC2119].  Although these keywords are often used
   to specify normative requirements in IETF Standards, their use in
   this document does not imply that this document is a standard of any
   kind.










































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3.  The EUI48 Resource Record

   The EUI48 Resource Record (RR) is used to store a single EUI-48
   address in the DNS.

   The Type value for the EUI48 RRType is 108 (decimal).

   The EUI48 RR is class-independent.

   The EUI48 RR has no special Time-to-Live (TTL) requirements.

3.1.  EUI48 RDATA Wire Format

   The RDATA for an EUI48 RR consists of a single, 6-octet EUI48-Address
   field, encoded in network (big-endian) order.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          EUI48-Address                        |
      |                               +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

3.2.  EUI48 RR Presentation Format

   The Address field MUST be represented as six two-digit hexadecimal
   numbers separated by hyphens.  The hexadecimal digits "A" through "F"
   MAY be represented in either upper or lower case.

3.3.  Example

   The following EUI48 RR stores the EUI-48 unicast address 00-00-5e-00-
   53-2a.

     host.example. 86400 IN EUI48 00-00-5e-00-53-2a















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4.  The EUI64 Resource Record

   The EUI64 RR is used to store a single EUI-64 address in the DNS.

   The Type value for the EUI64 RR is 109 (decimal).

   The EUI64 RR is class-independent.

   The EUI64 RR has no special TTL requirements.

4.1.  EUI64 RDATA Wire Format

   The RDATA for an EUI64 RR consists of a single, 8-octet Address
   field, encoded in network (big-endian) order.

       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          EUI-64 Address                       |
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

4.2.  EUI64 RR Presentation Format

   The Address field MUST be represented as eight two-digit hexadecimal
   numbers separated by hyphens.  The hexadecimal digits "A" through "F"
   MAY be represented in either upper or lower case.

4.3.  Example

   The following EUI64 RR stores the EUI-64 address 00-00-5e-ef-10-00-
   00-2a.

     host.example. 86400 IN EUI64 00-00-5e-ef-10-00-00-2a

















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5.  Example Use-Case: IP Address Tracking in DOCSIS Networks

   Canadian cable Internet subscribers are assigned IP addresses using
   DHCP, using a DHCP server operated by a cable company.  In the case
   where a cable company provides last-mile connectivity to a subscriber
   on behalf of a third party company (reseller), the DHCP server
   assigns addresses from a pool supplied by the reseller.  The reseller
   retains knowledge of the EUI-48 address of the DOCSIS modem supplied
   to the subscriber, but has no direct knowledge of the IP addresses
   assigned.  In order for the reseller to be able to map the IP address
   assigned to a subscriber to that EUI-48 address (and hence to the
   subscriber identity), the cable company can make available
   information from the DHCP server which provides that (EUI-48, IP)
   address mapping.

   Cable companies in Canada are required [NTRE038D] to make this
   address mapping available using the DNS.  Zones containing the
   relevant information are published on DNS servers, access to which is
   restricted to the resellers corresponding to particular sets of
   subscribers.  Subscriber address information is not published in the
   public DNS.

   Existing DNS schemas for the representation of (EUI-48, IP) mapping
   used by Canadian cable companies are varied and inefficient; in the
   absence of a RRType for direct encoding of EUI-48 addresses,
   addresses are variously encoded into owner names or are published in
   TXT records.

   The specification in this document facilitates a more efficient,
   consistent and reliable representation of (EUI-48, IP) mapping than
   was previously available.




















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6.  DNS Protocol Considerations

   The specification of the new RRTypes in this document has no effect
   on the address resolution behaviour of any previously existing
   network processes or protocols.  Proposals or specifications to
   modify or augment address resolution processes or protocols by making
   use of these RRTypes should specify how any address conflicts or use
   of multiple EUI48/EUI64 RRs are handled.











































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7.  IANA Considerations

   IANA has assigned the RRType value 108 (decimal) for EUI48 and 109
   (decimal) for EUI64.  This document directs the IANA to confirm that
   the corresponding entries in the "Resource Record (RR) TYPEs" sub-
   registry match the following data:

           +-------+-------+-------------------+---------------+
           | Type  | Value | Meaning           | Reference     |
           +-------+-------+-------------------+---------------+
           | EUI48 | 108   | an EUI-48 address | this document |
           |       |       |                   |               |
           | EUI64 | 109   | an EUI-64 address | this document |
           +-------+-------+-------------------+---------------+





































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8.  Security Considerations

   There are privacy concerns with the publication of link-layer
   addresses in the DNS.  EUI-48 and EUI-64 addresses with the Local/
   Global bit zero [RFC5342] (referred to in [RFC4291] as the universal/
   local bit) are intended to represent unique identifiers for network
   connected equipment, notwithstanding many observed cases of
   duplication due to manufacturing errors, unauthorised use of OUIs,
   and address spoofing through configuration of network interfaces.
   Publication of EUI-48 or EUI-64 addresses in the DNS may result in
   privacy issues in the form of unique trackable identities that in
   some cases may be permanent.

   For example, although IP addresses and DNS names for network devices
   typically change over time, EUI-48 and EUI-64 addresses configured on
   the same devices are normally far more stable (in many cases,
   effectively invariant).  Publication of EUI-48 addresses associated
   with user devices in a way that could be mapped to assigned IP
   addresses would allow the behaviour of those users to be tracked by
   third parties, regardless of where and how the user's device is
   connected to the Internet.  This might well result in a loss of
   privacy for the user.

   The publication of EUI-48 or EUI-64 addresses associated with
   deployed equipment, using the mechanism described in this document or
   any other mechanism, has the potential to facilitate MAC cloning --
   that is, facilitate link-layer attacks against deployed devices, e.g.
   to disrupt service or intercept data.

   These concerns can be mitigated by restricting access to DNS zones
   containing EUI48 or EUI64 RRs to specific, authorised clients and by
   provisioning them in DNS zones that exist in private namespaces only.

   This document recommends that EUI-48 or EUI-64 addresses SHOULD NOT
   be published in the public DNS.
















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9.  Acknowledgements

   The author acknowledges the contributions of Olafur Gudmundsson, Mark
   Smith, Andrew Sullivan, Roy Arends, Michael StJohns, Donald Eastlake
   III, Randy Bush and John Klensin.














































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10.  References

10.1.  Normative References

   [EUI48]    IEEE, "Guidelines for use of a 48-bit Extended Unique
              Identifier (EUI-48)".

   [EUI64]    IEEE, "Guidelines for use of a 64-bit Extended Unique
              Identifier (EUI-64)".

   [RFC1034]  Mockapetris, P., "Domain names - concepts and facilities",
              STD 13, RFC 1034, November 1987.

   [RFC1035]  Mockapetris, P., "Domain names - implementation and
              specification", STD 13, RFC 1035, November 1987.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC5342]  Eastlake, D., "IANA Considerations and IETF Protocol Usage
              for IEEE 802 Parameters", BCP 141, RFC 5342,
              September 2008.

10.2.  Informative References

   [NTRE038D]
              CRTC Interconnection Steering Committee Network Working
              Group, "Implementation of IP Address Tracking in DOCSIS
              Networks (TIF18)", October 2006.

10.3.  Informative References

   [RFC4291]  Hinden, R. and S. Deering, "IP Version 6 Addressing
              Architecture", RFC 4291, February 2006.

















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Appendix A.  Editorial Notes

   This section (and sub-sections) to be removed prior to publication.

A.1.  RRType Parameter Allocation Template

                   DNS RRTYPE PARAMETER ALLOCATION TEMPLATE

     A. Submission Date: 2013-03-18

     B.1 Submission Type:  [X] New RRTYPE  [ ] Modification to RRTYPE
     B.2 Kind of RR:  [X] Data RR  [ ] Meta-RR

     C. Contact Information for submitter (will be publicly posted):
           Name: Joe Abley
           Email Address: jabley@teksavvy.ca
           International telephone number: +1 519 670 9327
           Other contact handles:

     D. Motivation for the new RRTYPE application.

        The purpose of this RRTYPE application is to allow EUI-48
        and EUI-64 addresses to be stored in the DNS. EUI-48
        addresses are those used, for example, in ethernet.

     E. Description of the proposed RR type.

        See draft-jabley-dnsext-eui48-eui64-rrtypes for a full
        description.

     F. What existing RRTYPE or RRTYPEs come closest to filling that
        need and why are they unsatisfactory?

        The TXT record can be used to store arbitrary, unstructured
        data in the DNS and hence could be used to store EUI-48 and
        EUI-64 addresses. This approach is unsatisfactory for the
        usual reasons, i.e. there is no opportunity for validating
        data before it is stored, and typographical errors must
        consequently be detected after data retrieval.

     G. What mnemonic is requested for the new RRTYPE (optional)?

        EUI48 for EUI-48 addresses; EUI64 for EUI-64 addresses.

     H. Does the requested RRTYPE make use of any existing IANA
        registry or require the creation of a new IANA sub-registry
        in DNS Parameters?  If so, please indicate which registry is
        to be used or created. If a new sub-registry is needed, specify



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        the allocation policy for it and its initial contents. Also
        include what the modification procedures will be.

        No.

     I. Does the proposal require/expect any changes in DNS
        servers/resolvers that prevent the new type from being processed
        as an unknown RRTYPE (see [RFC3597])?

        No.

     J. Comments:

        See draft-jabley-dnsext-eui48-eui64-rrtypes for a complete
        specification.

A.2.  Change History

   00 Initial idea, circulated for the purposes of entertainment.

   01 Presentation format changed from colon-separated to hyphen-
      separated, to better match conventional usage for big-endian
      representations of EUI-48 and EUI-64 addresses.  IEEE trademarks
      acknowledged.  Code-points assigned by expert review.  Other minor
      tweaks and fixes based on early review.

   02 Example EUI64 presentation format in text corrected (colons ->
      hyphens).  Examples changed to use to-be-assigned addresses under
      the IANA OUI.

   03 Example EUI48 and EUI64 addresses changed to match the guidance in
      draft-eastlake-5342bis-00.  "EUI48" corrected to "EUI64" in the
      text of Section 4.1.  Incorporated suggestions on DNS resolution
      and privacy considerations from Michael StJohns and Donald
      Eastlake III.  Added example use case relating to Canadian DOCSIS
      networks.

   04 Incorporated suggestions from John Klensin.  Intended status
      changed to informational from standards track.  Moved examples to
      a more sensible place.

   05 Add emphasis that the publication of link-layer addresses in the
      DNS has potentially severe privacy implications, and is not
      recommended by this document.  Recommend that publication of link-
      layer addresses in the public DNS should not happen at all.
      Various wordsmithing for the purposes of clarity.





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   06 Add text regarding MAC cloning in the Security Considerations
      section.  Make text that mentions the "Global bit" more consistent
      with [RFC5342] and [RFC4291].

   07 Make the "SHOULD NOT publish in the public DNS" recommendation
      stronger.













































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Author's Address

   Joe Abley
   TekSavvy Solutions, Inc.
   470 Moore Street
   London, ON  N6C 2C2
   Canada

   Phone: +1 519 670 9327
   Email: jabley@teksavvy.ca









































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