Deprecation of Type 0 Routing Headers in IPv6
RFC 5095
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RFC - Proposed Standard
(December 2007; No errata)
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2015-10-14
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RFC 5095 (Proposed Standard)
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Jari Arkko
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Network Working Group J. Abley
Request for Comments: 5095 Afilias
Updates: 2460, 4294 P. Savola
Category: Standards Track CSC/FUNET
G. Neville-Neil
Neville-Neil Consulting
December 2007
Deprecation of Type 0 Routing Headers in IPv6
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Abstract
The functionality provided by IPv6's Type 0 Routing Header can be
exploited in order to achieve traffic amplification over a remote
path for the purposes of generating denial-of-service traffic. This
document updates the IPv6 specification to deprecate the use of IPv6
Type 0 Routing Headers, in light of this security concern.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Deprecation of RH0 . . . . . . . . . . . . . . . . . . . . . . 3
4. Operations . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4.1. Ingress Filtering . . . . . . . . . . . . . . . . . . . . . 3
4.2. Firewall Policy . . . . . . . . . . . . . . . . . . . . . . 3
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 4
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5
8.1. Normative References . . . . . . . . . . . . . . . . . . . 5
8.2. Informative References . . . . . . . . . . . . . . . . . . 5
Abley, et al. Standards Track [Page 1]
RFC 5095 Deprecation of RH0 December 2007
1. Introduction
[RFC2460] defines an IPv6 extension header called "Routing Header",
identified by a Next Header value of 43 in the immediately preceding
header. A particular Routing Header subtype denoted as "Type 0" is
also defined. Type 0 Routing Headers are referred to as "RH0" in
this document.
A single RH0 may contain multiple intermediate node addresses, and
the same address may be included more than once in the same RH0.
This allows a packet to be constructed such that it will oscillate
between two RH0-processing hosts or routers many times. This allows
a stream of packets from an attacker to be amplified along the path
between two remote routers, which could be used to cause congestion
along arbitrary remote paths and hence act as a denial-of-service
mechanism. An 88-fold amplification has been demonstrated using this
technique [CanSecWest07].
This attack is particularly serious in that it affects the entire
path between the two exploited nodes, not only the nodes themselves
or their local networks. Analogous functionality may be found in the
IPv4 source route option, but the opportunities for abuse are greater
with RH0 due to the ability to specify many more intermediate node
addresses in each packet.
The severity of this threat is considered to be sufficient to warrant
deprecation of RH0 entirely. A side effect is that this also
eliminates benign RH0 use-cases; however, such applications may be
facilitated by future Routing Header specifications.
Potential problems with RH0 were identified in 2001 [Security]. In
2002 a proposal was made to restrict Routing Header processing in
hosts [Hosts]. These efforts resulted in the modification of the
Mobile IPv6 specification to use the type 2 Routing Header instead of
RH0 [RFC3775]. Vishwas Manral identified various risks associated
with RH0 in 2006 including the amplification attack; several of these
vulnerabilities (together with other issues) were later documented in
[RFC4942].
A treatment of the operational security implications of RH0 was
presented by Philippe Biondi and Arnaud Ebalard at the CanSecWest
conference in Vancouver, 2007 [CanSecWest07]. This presentation
resulted in widespread publicity for the risks associated with RH0.
This document updates [RFC2460] and [RFC4294].
Abley, et al. Standards Track [Page 2]
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