One document matched: draft-gont-tsvwg-source-quench-00.txt
Transport Area Working Group F. Gont
(tsvwg) UTN/FRH
Internet-Draft September 24, 2010
Updates: 792, 1122
(if approved)
Intended status: Standards Track
Expires: March 28, 2011
Deprecation of ICMP Source Quench messages
draft-gont-tsvwg-source-quench-00.txt
Abstract
This document formally deprecates the use of ICMP Source Quench
messages by transport protocols.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on March 28, 2011.
Copyright Notice
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Internet-Draft Deprecation of ICMP Source Quench September 2010
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. ICMP Source Quench messages . . . . . . . . . . . . . . . . . . 3
3. Updating RFC 792 and RFC 1122 . . . . . . . . . . . . . . . . . 3
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 4
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 4
7.1. Normative References . . . . . . . . . . . . . . . . . . . 4
7.2. Informative References . . . . . . . . . . . . . . . . . . 5
Appendix A. Survey of support of ICMP Source Quench in some
popular TCP/IP implementations . . . . . . . . . . . . 5
Appendix B. Changes from previous versions of the draft (to
be removed by the RFC Editor before publishing
this document as an RFC) . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 5
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Internet-Draft Deprecation of ICMP Source Quench September 2010
1. Introduction
The ICMP specification [RFC0792] defines the ICMPv4 Source Quench
message (type 4, code 0), which is meant as a mechanism for
congestion control. ICMP Source Quench is known to be an ineffective
(and unfair) antidote for congestion, and generation of ICMP Source
Quench messages by routers has been deprecated by [RFC1812] for a
long time. However, reaction to ICMP Source Quench messages in
transport protocols has never been formally deprecated.
This document formally deprecates reaction to ICMP Source Quench
messages by transport protocols such as TCP.
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].
2. ICMP Source Quench messages
The ICMP specification [RFC0792] defines the ICMP Source Quench
message (type 4, code 0), which is meant to provide a mechanism for
congestion control. The Host Requirements RFC [RFC1122] states in
Section 4.2.3.9 that hosts MUST react to ICMP Source Quench messages
by slowing transmission on the connection, and further adds that the
RECOMMENDED procedure is to put the corresponding connection in the
slow-start phase of TCP's congestion control algorithm [RFC5681].
[RFC1812] notes that research suggests that ICMP Source Quench is an
ineffective (and unfair) antidote for congestion, and formally
deprecates the generation of ICMP Source Quench messages by routers,
stating that routers SHOULD NOT send ICMP Source Quench messages in
response to congestion.
[RFC5927] discusses the use of ICMP Source Quench messages for
performing "blind throughput-reduction" attacks, and notes that most
TCP implementations silently ignore ICMP Source Quench messages.
We note that TCP implements its own congestion control mechanisms
[RFC5681] [RFC3168], that do not depend on ICMP Source Quench
messages.
3. Updating RFC 792 and RFC 1122
If an ICMP Source Quench message is received by a transport-protocol
instance (e.g., a TCP connection), it SHOULD be silently ignored.
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Internet-Draft Deprecation of ICMP Source Quench September 2010
4. Security Considerations
ICMP Source Quench messages can be leveraged for performing blind
throughput-reduction attacks against TCP and similar protocols. This
attack vector, along with possible countermeasures, have been
discussed in great detail in [RFC5927] and [CPNI-TCP].
Silently ignoring ICMP Source Quench messages, as specified in this
document, eliminates the aforementioned attack vector.
5. IANA Considerations
This document has no actions for IANA. The RFC-Editor can remove
this section before publication of this document as an RFC.
6. Acknowledgements
This document has benefited from discussions within the TCPM Working
Group while working on [RFC5927].
7. References
7.1. Normative References
[RFC0792] Postel, J., "Internet Control Message Protocol", STD 5,
RFC 792, September 1981.
[RFC0793] Postel, J., "Transmission Control Protocol", STD 7,
RFC 793, September 1981.
[RFC1122] Braden, R., "Requirements for Internet Hosts -
Communication Layers", STD 3, RFC 1122, October 1989.
[RFC1812] Baker, F., "Requirements for IP Version 4 Routers",
RFC 1812, June 1995.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3168] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition
of Explicit Congestion Notification (ECN) to IP",
RFC 3168, September 2001.
[RFC5681] Allman, M., Paxson, V., and E. Blanton, "TCP Congestion
Control", RFC 5681, September 2009.
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7.2. Informative References
[CPNI-TCP]
CPNI, "Security Assessment of the Transmission Control
Protocol (TCP)", http://www.cpni.gov.uk/Docs/
tn-03-09-security-assessment-TCP.pdf, 2009.
[FreeBSD] The FreeBSD Project, "http://www.freebsd.org".
[Linux] The Linux Project, "http://www.kernel.org".
[NetBSD] The NetBSD Project, "http://www.netbsd.org".
[OpenBSD] The OpenBSD Project, "http://www.openbsd.org".
[RFC5927] Gont, F., "ICMP Attacks against TCP", RFC 5927, July 2010.
Appendix A. Survey of support of ICMP Source Quench in some popular
TCP/IP implementations
A large number of implementations completely ignore ICMP Source
Quench messages meant for TCP connections. This behavior has been
implemented in, at least, Linux [Linux] since 2004, and in FreeBSD
[FreeBSD], NetBSD [NetBSD], and OpenBSD [OpenBSD] since 2005.
Appendix B. Changes from previous versions of the draft (to be removed
by the RFC Editor before publishing this document as an
RFC)
Author's Address
Fernando Gont
Universidad Tecnologica Nacional / Facultad Regional Haedo
Evaristo Carriego 2644
Haedo, Provincia de Buenos Aires 1706
Argentina
Phone: +54 11 4650 8472
Email: fernando@gont.com.ar
URI: http://www.gont.com.ar
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