Internet DRAFT - draft-hain-ipv6-rpf-icmp

draft-hain-ipv6-rpf-icmp






Network Working Group                                            T. Hain
Internet-Draft                                             Cisco Systems
Intended status:  Standards Track                           Oct 15, 2010
Expires:  April 18, 2011


            IPv6 Reverse Path Forwarding ICMP error message
                      draft-hain-ipv6-rpf-icmp-00

Abstract

   This document specifies an icmp error message for use when the IPv6
   source address has failed a reverse-path-forwarding (RPF) check.

   The draft is being discussed on the ipv6@ietf.org list.

Legal

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   This Internet-Draft will expire on April 18, 2011.

Copyright Notice

   Copyright (c) 2010 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
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 4
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 4
   3.  Mechanisms  . . . . . . . . . . . . . . . . . . . . . . . . . . 4
     3.1.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . 4
     3.2.  ReversePathForwarding ICMP Error Message  . . . . . . . . . 4
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
   5.  Security Considerations . . . . . . . . . . . . . . . . . . . . 5
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 6
   7.  Pending comments  . . . . . . . . . . . . . . . . . . . . . . . 6
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 6
     8.1.  Normative References  . . . . . . . . . . . . . . . . . . . 6
     8.2.  Informative References  . . . . . . . . . . . . . . . . . . 6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . . 6




































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1.  Introduction

   A form of ingress traffic filtering commonly known as reverse path
   forwarding check is discussed in RFC 2827 [RFC2827]While the specific
   discussion in that document is focused on protecting against source
   address spoofing attacks by silently dropping the packets, there are
   instances when multi-homed IPv6 nodes have a mismatch between the
   source address and the selected path where the desired action SHOULD
   be to inform and provide a hint.  This document defines an icmp error
   message to inform a source that the packet is being dropped because
   the source address used would not work as a destination for packets
   returning over this path.  To avoid the situation where this
   informational back channel could be used as a denial of service
   attack, these icmp error messages MUST be rate limited.


2.  Terminology

   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.  Mechanisms

3.1.  Overview

3.2.  ReversePathForwarding ICMP Error Message

   Informing the origin that the source prefix is not appropriate for
   the next hop as a symmetric return path.
       0                   1                   2                   3
       0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     Type      |     Code      |          Checksum             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                         Prefix Length                         |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                                                               |
      +                                                               +
      |                 Source Prefix for this Path                   |
      +                                                               +
      |                                                               |
      +                                                               +
      |                                                               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |     MAC-type      |              MAC-length                   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



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      |                                                               |
      +                                                               +
      |                 Message Authentication Code                   |
      +                                                               +
      |                                                               |
      +                                                               +

   IPv6 Fields:

      Destination Address

                           Copied from the Source Address field of the
                           invoking packet.

      ICMPv6 Fields:

      Type           ???? --- 6

      Code           0 - unsigned
                       1 - signed

      Reserved             32-bit reserved field.  Initialized to zero
                           for transmission; ignored on reception.


      MAC-type       0 - unused
                       1 - HMAC-SHA1
                       2 - AES-CMAC
                       ...

      MAC-length    Length of the message authentication option

      MAC           Value of the message authenticator

   The optional authentication covers the source and destination address
   of this specific packet exchange, plus the return-via address.


4.  IANA Considerations

   This specification registers an IPv6 ICMP error message type


5.  Security Considerations

   The IPv6 ICMP RPF-error messages represents a potential denial of
   service attack vector, and therefore these messages MUST be rate
   limited by receivers.



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6.  Acknowledgements

   The general need for some way to inform multi-homed IPv6 nodes about
   an RPF check failure has been discussed in multiple sessions at IETF
   77 and 78.


7.  Pending comments


8.  References

8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

8.2.  Informative References

   [RFC2827]  Abley, J., "Deprecation of Type 0 Routing Headers in
              IPv6", RFC 5095, December 2007.


Author's Address

   Tony Hain
   Cisco Systems
   500 108th Ave NE
   Bellevue, WA  98004
   USA

   Phone:  +1 425 468-1061
   Email:  alh-ietf@tndh.net


















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