IPv6 maintenance Working Group (6man) F. Gont
Internet-Draft SI6 Networks / UTN-FRH
Updates: 2464, 2467, 2470, 2491, 2492, A. Cooper
2497, 2590, 3146, 3572, 4291, Cisco
4338, 4391, 4944, 5072, 5121 D. Thaler
(if approved) Microsoft
Intended status: Standards Track W. Liu
Expires: February 20, 2016 Huawei Technologies
August 19, 2015
Recommendation on Stable IPv6 Interface Identifiers
draft-ietf-6man-default-iids-06
Abstract
The IPv6 addressing architecture defines Modified EUI-64 format
Interface Identifiers, and the existing IPv6 over various link-layers
specify how such identifiers are derived from the underlying link-
layer address (e.g., an IEEE LAN MAC address) when employing IPv6
Stateless Address Autoconfiguration (SLAAC). The security and
privacy implications of embedding link-layer addresses in the
Interface Identifier have been known and understood for some time
now, and some popular IPv6 implementations have already deviated from
such schemes to mitigate these issues. This document changes the
recommended default Interface Identifier generation scheme for SLAAC
to that specified in RFC7217, and recommends against embedding link-
layer addresses in IPv6 Interface Identifiers. It formally updates
RFC2464, RFC2467, RFC2470, RFC2491, RFC2492, RFC2497, RFC2590,
RFC3146, RFC3572, RFC4291, RFC4338, RFC4391, RFC4944, RFC5072, and
RFC5121, which require IPv6 Interface Identifiers to be derived from
the underlying link-layer address. Additionally, this document
provides advice about the generation of Interface Identifiers with
other address configuration mechanisms, such as Dynamic Host
Configuration Protocol version 6 (DHCPv6) and manual configuration.
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
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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 20, 2016.
Copyright Notice
Copyright (c) 2015 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. 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.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Generation of IPv6 Interface Identifiers with SLAAC . . . . . 4
4. Generation of IPv6 Interface Identifiers with DHCPv6 . . . . 4
5. Generation of IPv6 Interface Identifiers with Manual
Configuration . . . . . . . . . . . . . . . . . . . . . . . . 5
6. Future Work . . . . . . . . . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
8. Security Considerations . . . . . . . . . . . . . . . . . . . 5
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
10.1. Normative References . . . . . . . . . . . . . . . . . . 6
10.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
[RFC4862] specifies Stateless Address Autoconfiguration (SLAAC) for
IPv6 [RFC2460], which typically results in hosts configuring one or
more "stable" addresses composed of a network prefix advertised by a
local router, and an Interface Identifier (IID) [RFC4291] that
typically embeds a link-layer address (e.g., an IEEE LAN MAC
address).
In some network technologies and adaptation layers, the use of an IID
based on a link-layer address may offer some advantages. For
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example, the IP-over-IEEE802.15.4 standard in [RFC6775] allows for
compression of IPv6 addresses when the IID is based on the underlying
link-layer address.
The security and privacy implications of embedding a link-layer
address in an IPv6 IID have been known for some time now, and are
discussed in great detail in
[I-D.ietf-6man-ipv6-address-generation-privacy]; they include:
o Network activity correlation
o Location tracking
o Address scanning
o Device-specific vulnerability exploitation
Some popular IPv6 implementations have already deviated from the
traditional stable IID generation scheme to mitigate the
aforementioned security and privacy implications [Microsoft].
As a result of the aforementioned issues, this document recommends
the implementation of an alternative scheme ([RFC7217]) as the
default stable IID generation scheme for SLAAC, such that the
aforementioned issues are mitigated.
NOTE: [RFC4291] defines the "Modified EUI-64 format" for IIDs.
Appendix A of [RFC4291] then describes how to transform an IEEE
EUI-64 identifier, or an IEEE 802 48-bit MAC address from which an
EUI-64 identifier is derived, into an IID in the Modified EUI-64
format.
Finally this document provides advice about the generation of
Interface Identifiers with other address configuration mechanisms,
such as Dynamic Host Configuration Protocol version 6 (DHCPv6) and
manual configuration.
2. Terminology
Stable address:
An address that does not vary over time within the same network
(as defined in [I-D.ietf-6man-ipv6-address-generation-privacy]).
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
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3. Generation of IPv6 Interface Identifiers with SLAAC
Link layers MUST define a mechanism that provides mitigation of the
security and privacy implications discussed in Section 1. Nodes
SHOULD implement and employ [RFC7217] as the default scheme for
generating stable IPv6 addresses with SLAAC. A link layer MAY also
define a mechanism that is more efficient and does not address the
security and privacy considerations discussed in Section 1. The
choice of whether to enable privacy or not SHOULD be configurable in
such a case.
By default, nodes SHOULD NOT employ IPv6 address generation schemes
that embed the underlying link-layer address in the IID. In
particular, this document RECOMMENDS that nodes do not generate IIDs
with the schemes specified in [RFC2464], [RFC2467], [RFC2470],
[RFC2491], [RFC2492], [RFC2497], [RFC2590], [RFC3146], [RFC3572],
[RFC4338], [RFC4391], [RFC4944], [RFC5121], and [RFC5072], and
updates these documents with this recommendation.
Some link-layers support locally assigned link-layer addresses
[IEEE-802], such as [IEEE-802.3] and [IEEE-802.11], or random
addresses [BLUETOOTH]. Where IPv6 IIDs are to be derived from link-
layer addresses, it is RECOMMENDED that the random addresses
supported by the link-layer are used, or that pseudo-random locally
assigned link-layer addresses are generated, assigned and used.
Future specifications SHOULD NOT specify IPv6 address generation
schemes that embed the underlying link-layer address in the IID. In
some cases, embedding the link-layer address in the IID may reduce
resource requirements such as energy, bandwidth and number of frames
to carry a given IPv6 packet by facilitating header compression in
constrained devices. In such cases, future specifications MAY
include IPv6 address generation schemes that embed the link-layer
address in the IID, but MUST also specify an alternative IPv6 address
generation scheme that provides mitigation of the security and
privacy implications discussed in Section 1.
4. Generation of IPv6 Interface Identifiers with DHCPv6
By default, DHCPv6 server implementations SHOULD NOT generate
predictable IPv6 addresses (such as IPv6 addresses where the IIDs are
consecutive small numbers). [I-D.ietf-dhc-stable-privacy-addresses]
specifies one possible algorithm that could be employed to comply
with this requirement. Another possible algorithm would be to select
a pseudo-random value chosen from a discrete uniform distribution,
while avoiding the reserved IPv6 Interface Identifiers [RFC5453]
[IANA-RESERVED-IID].
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5. Generation of IPv6 Interface Identifiers with Manual Configuration
Network administrators should be aware of the security implications
of predictable Interface Identifiers
[I-D.ietf-6man-ipv6-address-generation-privacy], and avoid the use of
predictable addresses when the aforementioned issues are of concern.
6. Future Work
At the time of this writing, the mechanisms specified in the
following documents might require updates to be fully compatible with
the recommendations in this document:
o RFC 6282 [RFC6282]
o RFC 4944 [RFC4944]
o RFC 6755 [RFC6775]
Future revisions or updates of these documents should take the issues
of privacy and security mentioned in Section 1 and explain any design
and engineering considerations that lead to the use of IIDs based on
a node's link-layer address.
7. IANA Considerations
There are no IANA registries within this document. The RFC-Editor
can remove this section before publication of this document as an
RFC.
8. Security Considerations
This document recommends [RFC7217] as the default scheme for
generating IPv6 stable addresses with SLAAC, such that the security
and privacy issues of IIDs that embed link-layer addresses are
mitigated.
9. Acknowledgements
The authors would like to thank Erik Nordmark and Ray Hunter for
providing a detailed review of this document.
The authors would like to thank (in alphabetical order) Fred Baker,
Carsten Bormann, Scott Brim, Brian Carpenter, Samita Chakrabarti, Tim
Chown, Lorenzo Colitti, Jean-Michel Combes, Greg Daley, Esko Dijk,
Ralph Droms, David Farmer, Brian Haberman, Ulrich Herberg, Bob
Hinden, Philip Homburg, Jahangir Hossain, Jonathan Hui, Christian
Huitema, Ray Hunter, Sheng Jiang, Roger Jorgensen, Dan Luedtke, Kerry
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Lynn, George Mitchel, Gabriel Montenegro, Erik Nordmark, Simon
Perreault, Tom Petch, Alexandru Petrescu, Michael Richardson, Arturo
Servin, Mark Smith, Tom Taylor, Ole Troan, Tina Tsou, Glen Turner,
Randy Turner, and James Woodyatt, for providing valuable comments on
earlier versions of this document.
10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
December 1998, <http://www.rfc-editor.org/info/rfc2460>.
[RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet
Networks", RFC 2464, DOI 10.17487/RFC2464, December 1998,
<http://www.rfc-editor.org/info/rfc2464>.
[RFC2467] Crawford, M., "Transmission of IPv6 Packets over FDDI
Networks", RFC 2467, DOI 10.17487/RFC2467, December 1998,
<http://www.rfc-editor.org/info/rfc2467>.
[RFC2470] Crawford, M., Narten, T., and S. Thomas, "Transmission of
IPv6 Packets over Token Ring Networks", RFC 2470,
DOI 10.17487/RFC2470, December 1998,
<http://www.rfc-editor.org/info/rfc2470>.
[RFC2492] Armitage, G., Schulter, P., and M. Jork, "IPv6 over ATM
Networks", RFC 2492, DOI 10.17487/RFC2492, January 1999,
<http://www.rfc-editor.org/info/rfc2492>.
[RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins,
C., and M. Carney, "Dynamic Host Configuration Protocol
for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July
2003, <http://www.rfc-editor.org/info/rfc3315>.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, <http://www.rfc-editor.org/info/rfc4291>.
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[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Address Autoconfiguration", RFC 4862,
DOI 10.17487/RFC4862, September 2007,
<http://www.rfc-editor.org/info/rfc4862>.
[RFC7217] Gont, F., "A Method for Generating Semantically Opaque
Interface Identifiers with IPv6 Stateless Address
Autoconfiguration (SLAAC)", RFC 7217,
DOI 10.17487/RFC7217, April 2014,
<http://www.rfc-editor.org/info/rfc7217>.
[RFC2491] Armitage, G., Schulter, P., Jork, M., and G. Harter, "IPv6
over Non-Broadcast Multiple Access (NBMA) networks",
RFC 2491, DOI 10.17487/RFC2491, January 1999,
<http://www.rfc-editor.org/info/rfc2491>.
[RFC2497] Souvatzis, I., "Transmission of IPv6 Packets over ARCnet
Networks", RFC 2497, DOI 10.17487/RFC2497, January 1999,
<http://www.rfc-editor.org/info/rfc2497>.
[RFC2590] Conta, A., Malis, A., and M. Mueller, "Transmission of
IPv6 Packets over Frame Relay Networks Specification",
RFC 2590, DOI 10.17487/RFC2590, May 1999,
<http://www.rfc-editor.org/info/rfc2590>.
[RFC3146] Fujisawa, K. and A. Onoe, "Transmission of IPv6 Packets
over IEEE 1394 Networks", RFC 3146, DOI 10.17487/RFC3146,
October 2001, <http://www.rfc-editor.org/info/rfc3146>.
[RFC3572] Ogura, T., Maruyama, M., and T. Yoshida, "Internet
Protocol Version 6 over MAPOS (Multiple Access Protocol
Over SONET/SDH)", RFC 3572, DOI 10.17487/RFC3572, July
2003, <http://www.rfc-editor.org/info/rfc3572>.
[RFC4338] DeSanti, C., Carlson, C., and R. Nixon, "Transmission of
IPv6, IPv4, and Address Resolution Protocol (ARP) Packets
over Fibre Channel", RFC 4338, DOI 10.17487/RFC4338,
January 2006, <http://www.rfc-editor.org/info/rfc4338>.
[RFC4391] Chu, J. and V. Kashyap, "Transmission of IP over
InfiniBand (IPoIB)", RFC 4391, DOI 10.17487/RFC4391, April
2006, <http://www.rfc-editor.org/info/rfc4391>.
[RFC4944] Montenegro, G., Kushalnagar, N., Hui, J., and D. Culler,
"Transmission of IPv6 Packets over IEEE 802.15.4
Networks", RFC 4944, DOI 10.17487/RFC4944, September 2007,
<http://www.rfc-editor.org/info/rfc4944>.
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[RFC5121] Patil, B., Xia, F., Sarikaya, B., Choi, JH., and S.
Madanapalli, "Transmission of IPv6 via the IPv6
Convergence Sublayer over IEEE 802.16 Networks", RFC 5121,
DOI 10.17487/RFC5121, February 2008,
<http://www.rfc-editor.org/info/rfc5121>.
[RFC5072] Varada, S., Ed., Haskins, D., and E. Allen, "IP Version 6
over PPP", RFC 5072, DOI 10.17487/RFC5072, September 2007,
<http://www.rfc-editor.org/info/rfc5072>.
[RFC5453] Krishnan, S., "Reserved IPv6 Interface Identifiers",
RFC 5453, DOI 10.17487/RFC5453, February 2009,
<http://www.rfc-editor.org/info/rfc5453>.
[RFC6282] Hui, J., Ed. and P. Thubert, "Compression Format for IPv6
Datagrams over IEEE 802.15.4-Based Networks", RFC 6282,
DOI 10.17487/RFC6282, September 2011,
<http://www.rfc-editor.org/info/rfc6282>.
[RFC6775] Shelby, Z., Ed., Chakrabarti, S., Nordmark, E., and C.
Bormann, "Neighbor Discovery Optimization for IPv6 over
Low-Power Wireless Personal Area Networks (6LoWPANs)",
RFC 6775, DOI 10.17487/RFC6775, November 2012,
<http://www.rfc-editor.org/info/rfc6775>.
10.2. Informative References
[IEEE-802]
IEEE, "802-2014 - IEEE Standard for Local and Metropolitan
Area Networks: Overview and Architecture", 2014,
<https://standards.ieee.org/findstds/
standard/802-2014.html>.
[IEEE-802.3]
IEEE, "802.3-2012 - IEEE Standard for Ethernet", 2012,
<https://standards.ieee.org/findstds/
standard/802.3-2012.html>.
[IEEE-802.11]
IEEE, "IEEE Standard for Information technology --
Telecommunications and information exchange between
systems -- Local and metropolitan area networks --
Specific requirements -- Part 11: Wireless LAN Medium
Access Control (MAC) and Physical Layer (PHY)
Specifications", 2012,
<http://standards.ieee.org/getieee802/
download/802.11-2012.pdf>.
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[BLUETOOTH]
Bluetooth SIG, "BLUETOOTH SPECIFICATION Version 4.2",
2014, <https://www.bluetooth.org/DocMan/handlers/
DownloadDoc.ashx?doc_id=286439>.
[IANA-RESERVED-IID]
IANA, "Reserved IPv6 Interface Identifiers",
<http://www.iana.org/assignments/ipv6-interface-ids>.
[I-D.ietf-6man-ipv6-address-generation-privacy]
Cooper, A., Gont, F., and D. Thaler, "Privacy
Considerations for IPv6 Address Generation Mechanisms",
draft-ietf-6man-ipv6-address-generation-privacy-07 (work
in progress), June 2015.
[I-D.ietf-dhc-stable-privacy-addresses]
Gont, F. and S. LIU, "A Method for Generating Semantically
Opaque Interface Identifiers with Dynamic Host
Configuration Protocol for IPv6 (DHCPv6)", draft-ietf-dhc-
stable-privacy-addresses-02 (work in progress), April
2015.
[Microsoft]
Davies, J., "Understanding IPv6, 3rd. ed", page 83,
Microsoft Press, 2012, <http://it-ebooks.info/book/1022/>.
Authors' Addresses
Fernando Gont
SI6 Networks / UTN-FRH
Evaristo Carriego 2644
Haedo, Provincia de Buenos Aires 1706
Argentina
Phone: +54 11 4650 8472
Email: fgont@si6networks.com
URI: http://www.si6networks.com
Alissa Cooper
Cisco
707 Tasman Drive
Milpitas, CA 95035
US
Phone: +1-408-902-3950
Email: alcoop@cisco.com
URI: https://www.cisco.com/
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Dave Thaler
Microsoft
Microsoft Corporation
One Microsoft Way
Redmond, WA 98052
Phone: +1 425 703 8835
Email: dthaler@microsoft.com
Will Liu
Huawei Technologies
Bantian, Longgang District
Shenzhen 518129
P.R. China
Email: liushucheng@huawei.com
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