Internet DRAFT - draft-jabley-dnsext-eui48-eui64-rrtypes
draft-jabley-dnsext-eui48-eui64-rrtypes
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 EUI-48 or EUI-64 addresses SHOULD NOT be published in the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
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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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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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