Internet DRAFT - draft-ietf-6man-default-iids
draft-ietf-6man-default-iids
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, 5072, 5121 (if D. Thaler
approved) Microsoft
Intended status: Standards Track W. Liu
Expires: March 29, 2017 Huawei Technologies
September 28, 2016
Recommendation on Stable IPv6 Interface Identifiers
draft-ietf-6man-default-iids-16
Abstract
This document changes the recommended default IID generation scheme
for cases where SLAAC is used to generate a stable IPv6 address. It
recommends using the mechanism specified in RFC7217 in such cases,
and recommends against embedding stable link-layer addresses in IPv6
Interface Identifiers. It formally updates RFC2464, RFC2467,
RFC2470, RFC2491, RFC2492, RFC2497, RFC2590, RFC3146, RFC3572,
RFC4291, RFC4338, RFC4391, RFC5072, and RFC5121. This document does
not change any existing recommendations concerning the use of
temporary addresses as specified in RFC 4941.
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
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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 21, 2017.
Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
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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
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Generation of IPv6 Interface Identifiers with SLAAC . . . . . 4
4. Future Work . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
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 stable 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
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 stable link-
layer address in an IPv6 IID have been known for some time now, and
are discussed in great detail in [RFC7721]. They include:
o Network activity correlation
o Location tracking
o Address scanning
o Device-specific vulnerability exploitation
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More generally, the reuse of identifiers that have their own
semantics or properties across different contexts or scopes can be
detrimental for security and privacy
[I-D.gont-predictable-numeric-ids]. In the case of traditional
stable IPv6 IIDs, some of the security and privacy implications are
dependent on the properties of the underlying link-layer addresses
(e.g., whether the link-layer address is ephemeral or randomly
generated), while other implications (e.g., reduction of the entropy
of the IID) depend on the algorithm for generating the IID itself.
In standardized recommendations for stable IPv6 IID generation meant
to achieve particular security and privacy properties, it is
therefore necessary to recommend against embedding stable link-layer
addresses in IPv6 IIDs.
Furthermore, 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 changes the
recommended default IID generation scheme for generating stable IPv6
addresses with SLAAC to that specified in [RFC7217], and recommends
against embedding stable link-layer addresses in IPv6 Interface
Identifiers, such that the aforementioned issues are mitigated. That
is, this document simply replaces the default algorithm that is
recommended to be employed when generating stable IPv6 IIDs.
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.
In a variety of scenarios, addresses that remain stable for the
lifetime of a host's connection to a single subnet, are viewed as
desirable. For example, stable addresses may be viewed as beneficial
for network management, event logging, enforcement of access control,
provision of quality of service, or for server or routing interfaces.
Similarly, stable addresses (as opposed to temporary addresses
[RFC4941]) allow for long-lived TCP connections, and are also usually
desirable when performing server-like functions (i.e., receiving
incoming connections).
The recommendations in this document apply only in cases where
implementations otherwise would have configured a stable IPv6 IID
containing a link layer address. For example, this document does not
change any existing recommendations concerning the use of temporary
addresses as specified in [RFC4941], nor do the recommendations apply
to cases where SLAAC is employed to generate non-stable IPv6
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addresses (e.g. by embedding a link-layer address that is
periodically randomized), nor does it introduce any new requirements
regarding when stable addresses are to be configured. Thus, the
recommendations in this document simply improve the security and
privacy properties of stable addresses.
2. Terminology
Stable address:
An address that does not vary over time within the same network
(as defined in [RFC7721]).
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].
3. Generation of IPv6 Interface Identifiers with SLAAC
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 for stable IPv6 address generation that is more
efficient and does not address the security and privacy
considerations discussed in Section 1. The choice of whether to
enable the security- and privacy-preserving mechanism or not SHOULD
be configurable in such a case.
By default, nodes SHOULD NOT employ IPv6 address generation schemes
that embed a stable link-layer address in the IID. In particular,
this document RECOMMENDS that nodes do not generate stable IIDs with
the schemes specified in [RFC2464], [RFC2467], [RFC2470], [RFC2491],
[RFC2492], [RFC2497], [RFC2590], [RFC3146], [RFC3572], [RFC4338],
[RFC4391], [RFC5121], and [RFC5072].
4. 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 "Compression Format for IPv6 Datagrams over IEEE 802.15.4-Based
Networks" [RFC6282]
o "Transmission of IPv6 Packets over IEEE 802.15.4 Networks"
[RFC4944]
o "Neighbor Discovery Optimization for IPv6 over Low-Power Wireless
Personal Area Networks (6LoWPANs)"[RFC6775]
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o "Transmission of IPv6 Packets over ITU-T G.9959 Networks" [RFC7428]
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 stable IIDs
based on a node's link-layer address.
5. 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.
6. Security Considerations
This recommends against the (default) use of predictable Interface
Identifiers in IPv6 addresses. It recommends [RFC7217] as the
default scheme for generating IPv6 stable addresses with SLAAC, such
that the security and privacy issues of IIDs that embed stable link-
layer addresses are mitigated.
7. Acknowledgements
The authors would like to thank (in alphabetical order) Bob Hinden,
Ray Hunter and Erik Nordmark, 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, Philip
Homburg, Jahangir Hossain, Jonathan Hui, Christian Huitema, Ray
Hunter, Erik Kline, Sheng Jiang, Roger Jorgensen, Dan Luedtke, Kerry
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, James Woodyatt, and Juan Carlos Zuniga, for providing
valuable comments on earlier versions of this document.
8. References
8.1. 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>.
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[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>.
[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>.
[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>.
[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>.
[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>.
[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>.
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[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>.
[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>.
[RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy
Extensions for Stateless Address Autoconfiguration in
IPv6", RFC 4941, DOI 10.17487/RFC4941, September 2007,
<http://www.rfc-editor.org/info/rfc4941>.
[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>.
[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>.
[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>.
[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>.
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[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>.
[RFC7428] Brandt, A. and J. Buron, "Transmission of IPv6 Packets
over ITU-T G.9959 Networks", RFC 7428,
DOI 10.17487/RFC7428, February 2015,
<http://www.rfc-editor.org/info/rfc7428>.
8.2. Informative References
[I-D.gont-predictable-numeric-ids]
Gont, F. and I. Arce, "Security and Privacy Implications
of Numeric Identifiers Employed in Network Protocols",
draft-gont-predictable-numeric-ids-00 (work in progress),
February 2016.
[Microsoft]
Davies, J., "Understanding IPv6, 3rd. ed", page 83,
Microsoft Press, 2012, <http://it-ebooks.info/book/1022/>.
[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>.
[RFC7721] Cooper, A., Gont, F., and D. Thaler, "Security and Privacy
Considerations for IPv6 Address Generation Mechanisms",
RFC 7721, DOI 10.17487/RFC7721, March 2016,
<http://www.rfc-editor.org/info/rfc7721>.
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
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Alissa Cooper
Cisco
707 Tasman Drive
Milpitas, CA 95035
US
Phone: +1-408-902-3950
Email: alcoop@cisco.com
URI: https://www.cisco.com/
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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