v6ops Working Group N. Hilliard
Internet-Draft INEX
Intended status: Informational October 10, 2011
Expires: April 12, 2012
A Discard Prefix for IPv6
draft-ietf-v6ops-ipv6-discard-prefix-00
Abstract
Remote triggered black hole filtering describes a method of
mitigating against denial-of-service attacks by selectively
discarding traffic based on source or destination address. This
document explains why a unique IPv6 prefix should be formally
assigned by IANA for the purpose of facilitating IPv6 remote
triggered black hole filtering.
Status of this Memo
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This Internet-Draft will expire on April 12, 2012.
Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved.
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Conventions . . . . . . . . . . . . . . . . . . . . . . . . 3
2. A Discard Prefix for IPv6 . . . . . . . . . . . . . . . . . . . 3
3. Operational Implications . . . . . . . . . . . . . . . . . . . 4
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . . 4
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 4
6.1. Normative References . . . . . . . . . . . . . . . . . . . 4
6.2. Informative References . . . . . . . . . . . . . . . . . . 4
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 5
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1. Introduction
Remote triggered black hole (RTBH) filtering describes a class of
methods of blocking IP traffic to or from a specific destination on a
network. These methods operate by setting the next-hop address of an
IP packet with a specified source or destination address to be a
unicast prefix which is wired locally or remotely to a router's
discard or null interface. Typically, this information is propagated
throughout an autonomous system using a dynamic routing protocol. By
deploying RTBH systems across a network, traffic to or from specific
destinations may be selectively black-holed in a manner which is
efficient, scalable and straightforward to implement. For IPv4, some
networks configure RTBH installations using [RFC1918] address space
or the address blocks reserved for documentation in [RFC5737].
However RTBH configurations are not documentation, but operationally
important features of many public-facing production networks.
Furthermore, [RFC3849] specifies that the IPv6 documentation prefix
should be filtered in both local and public contexts. On this basis,
it is suggested that both private network address blocks and
documentation prefixes described in [RFC5737] are inappropriate for
the purpose of RTBH configurations.
While it could be argued that there are other addresses and address
prefixes which could be used for this purpose (e.g. ::/128), or that
an operator could assign an address block from their own address
space for this purposes, there is currently no operational clarity on
what address block would be appropriate or inappropriate to use for
this purpose. By creating an assigned discard prefix for IPv6, the
IETF will introduce operational clarity and good practice for
implementation of IPv6 RTBH configurations.
1.1. Conventions
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 [RFC2119].
2. A Discard Prefix for IPv6
For the purposes of implementing an IPv6 remote triggered black hole
filter, a unicast address block is required. There are currently no
IPv6 unicast address blocks which are specifically nominated for the
purposes of implementing RTBH filters.
As [RFC5635] describes situations where more than one discard address
may be used for implementing multiple remote triggered black holes, a
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single assigned prefix is not sufficient to cover all likely RTBH
filtering situations. Consequently, an address block is required in
preference to a single address.
3. Operational Implications
This assignment MAY be carried in a dynamic routing protocol within
an autonomous system. The assignment SHOULD NOT be announced to
third party autonomous systems and IPv6 traffic with an destination
address within this prefix SHOULD NOT be forwarded to third party
autonomous systems.
On networks which implement IPv6 remote triggered black holes, some
or all of this network block MAY be configured with a destination of
a discard or null interface on any or all IPv6 routers within the
autonomous system.
4. IANA Considerations
This document directs IANA to record the allocation of the IPv6
address prefix xxxx/64 as a discard-only prefix in the IPv6 Address
Space registry. No end party is to be assigned this prefix. The
prefix should be allocated from ::/3.
5. Security Considerations
As the prefix specified in this document should not normally be
transmitted or accepted over inter-domain BGP sessions, it is
appropriate to label the prefix as a Martian ([RFC3704]) for
inclusion in inter-domain BGP prefix filters.
6. References
6.1. Normative References
[RFC5635] Kumari, W. and D. McPherson, "Remote Triggered Black Hole
Filtering with Unicast Reverse Path Forwarding (uRPF)",
RFC 5635, August 2009.
6.2. Informative References
[RFC1881] Internet Architecture Board and Internet Engineering
Steering Group, "IPv6 Address Allocation Management",
RFC 1881, December 1995.
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[RFC1918] Rekhter, Y., Moskowitz, R., Karrenberg, D., Groot, G., and
E. Lear, "Address Allocation for Private Internets",
BCP 5, RFC 1918, February 1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3704] Baker, F. and P. Savola, "Ingress Filtering for Multihomed
Networks", BCP 84, RFC 3704, March 2004.
[RFC3849] Huston, G., Lord, A., and P. Smith, "IPv6 Address Prefix
Reserved for Documentation", RFC 3849, July 2004.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC5737] Arkko, J., Cotton, M., and L. Vegoda, "IPv4 Address Blocks
Reserved for Documentation", RFC 5737, January 2010.
Author's Address
Nick Hilliard
INEX
4027 Kingswood Road
Dublin 24
IE
Email: nick@inex.ie
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