One document matched: draft-hain-ipv6-rpf-icmp-00.txt
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.
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Internet-Draft IPv6 RPF ICMP Oct 2010
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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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