Security Implications of IPv6 Fragmentation with IPv6 Neighbor Discovery
RFC 6980
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RFC - Proposed Standard
(August 2013; No errata)
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Last updated |
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2015-10-14
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draft-gont-6man-nd-extension-headers
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IETF
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Submitted to IESG for Publication
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Document shepherd |
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Robert Hinden
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(last changed 2012-12-10)
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RFC 6980 (Proposed Standard)
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Brian Haberman
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Internet Engineering Task Force (IETF) F. Gont
Request for Comments: 6980 SI6 Networks / UTN-FRH
Updates: 3971, 4861 August 2013
Category: Standards Track
ISSN: 2070-1721
Security Implications of IPv6 Fragmentation with IPv6 Neighbor Discovery
Abstract
This document analyzes the security implications of employing IPv6
fragmentation with Neighbor Discovery (ND) messages. It updates RFC
4861 such that use of the IPv6 Fragmentation Header is forbidden in
all Neighbor Discovery messages, thus allowing for simple and
effective countermeasures for Neighbor Discovery attacks. Finally,
it discusses the security implications of using IPv6 fragmentation
with SEcure Neighbor Discovery (SEND) and formally updates RFC 3971
to provide advice regarding how the aforementioned security
implications can be mitigated.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6980.
Gont Standards Track [Page 1]
RFC 6980 ND and IPv6 Fragmentation August 2013
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
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. Traditional Neighbor Discovery and IPv6 Fragmentation ...........4
3. SEcure Neighbor Discovery (SEND) and IPv6 Fragmentation .........5
4. Rationale for Forbidding IPv6 Fragmentation in Neighbor
Discovery .......................................................6
5. Specification ...................................................6
6. Operational Advice ..............................................7
7. Security Considerations .........................................7
8. Acknowledgements ................................................8
9. References ......................................................8
9.1. Normative References .......................................8
9.2. Informative References .....................................9
Appendix A. Message Size When Carrying Certificates ...............10
1. Introduction
The Neighbor Discovery Protocol (NDP) is specified in RFC 4861
[RFC4861]. It is used by both hosts and routers. Its functions
include Neighbor Discovery (ND), Router Discovery (RD), address
autoconfiguration, address resolution, Neighbor Unreachability
Detection (NUD), Duplicate Address Detection (DAD), and redirection.
Many of the possible attacks against the Neighbor Discovery Protocol
are discussed in detail in [RFC3756]. In order to mitigate the
aforementioned possible attacks, SEcure Neighbor Discovery (SEND) was
standardized. SEND employs a number of mechanisms to certify the
origin of Neighbor Discovery packets and the authority of routers,
and to protect Neighbor Discovery packets from being the subject of
modification or replay attacks.
Gont Standards Track [Page 2]
RFC 6980 ND and IPv6 Fragmentation August 2013
However, a number of factors, such as the high administrative
overhead of deploying trust anchors and the unavailability of SEND
implementations for many widely deployed operating systems, make SEND
hard to deploy [Gont-DPSC]. Thus, in many general scenarios, it may
be necessary and/or convenient to use other mitigation techniques for
NDP-based attacks. The following mitigations are currently available
for NDP attacks:
o Static Access Control Lists (ACLs) in switches
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