[Docs] [txt|pdf] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: (draft-gont-tsvwg-source-quench) 00 01 02 03 04 05 06 RFC 6633

Transport Area Working Group (tsvwg)                             F. Gont
Internet-Draft                                                   UTN/FRH
Updates: 792, 1122, 1812                               December 22, 2011
(if approved)
Intended status: Standards Track
Expires: June 24, 2012


               Deprecation of ICMP Source Quench messages
                 draft-ietf-tsvwg-source-quench-03.txt

Abstract

   This document formally deprecates the use of ICMP Source Quench
   messages by transport protocols, formally updating RFC 792, RFC 1122,
   and RFC 1812.  Additionally, it requests that the status of RFC 1016
   be changed to "Historic".

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
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on June 24, 2012.

Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as



Gont                      Expires June 24, 2012                 [Page 1]

Internet-Draft      Deprecation of ICMP Source Quench      December 2011


   described in the Simplified BSD License.


Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  ICMP Source Quench messages . . . . . . . . . . . . . . . . . . 3
   3.  Updating RFC 1122 . . . . . . . . . . . . . . . . . . . . . . . 4
   4.  Updating RFC 1812 . . . . . . . . . . . . . . . . . . . . . . . 4
   5.  Clarification for UDP, SCTP, and DCCP . . . . . . . . . . . . . 5
   6.  General Advice to Transport Protocols . . . . . . . . . . . . . 5
   7.  Changing the status of RFC 1016 to Historic . . . . . . . . . . 5
   8.  Security Considerations . . . . . . . . . . . . . . . . . . . . 5
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 6
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . . . 6
     11.1.  Normative References . . . . . . . . . . . . . . . . . . . 6
     11.2.  Informative References . . . . . . . . . . . . . . . . . . 7
   Appendix A.  Survey of support of ICMP Source Quench in some
                popular TCP/IP implementations . . . . . . . . . . . . 7
   Appendix B.  Changes from previous versions of the draft (to
                be removed by the RFC Editor before publishing
                this document as an RFC) . . . . . . . . . . . . . . . 8
     B.1.   Changes from draft-ietf-tsvwg-source-quench-01 . . . . . . 8
     B.2.   Changes from draft-ietf-tsvwg-source-quench-00 . . . . . . 8
     B.3.   Changes from draft-gont-tsvwg-source-quench-01 . . . . . . 8
     B.4.   Changes from draft-gont-tsvwg-source-quench-00 . . . . . . 8
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . . 8























Gont                      Expires June 24, 2012                 [Page 2]

Internet-Draft      Deprecation of ICMP Source Quench      December 2011


1.  Introduction

   The ICMP specification [RFC0792] defined the ICMP Source Quench
   message (type 4, code 0), which was meant as a mechanism for
   congestion control.  ICMP Source Quench has been known to be an
   ineffective (and unfair) antidote for congestion, and generation of
   ICMP Source Quench messages by routers has been formally deprecated
   by [RFC1812] since 1995.  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, formally updating
   [RFC0792], [RFC1122], and [RFC1812].  Additionally, it requests that
   the status of [RFC1016] be changed to "Historic".  The rationale for
   these specification updates is:

   o  Processing of ICMP Source Quench messages by routers has been
      deprecated for more than 20 years [RFC1812].

   o  Virtually all popular host implementations have removed support
      for ICMP Source Quench messages since (at least) 2005 [RFC5927].

   o  Widespread deployment of ICMP filtering makes it impossible to
      rely on ICMP Source Quench messages for congestion control.

   o  The IETF has moved away from ICMP Source Quench messages for
      congestion control (note e.g. the development of ECN [RFC3168],
      and the fact that ICMPv6 [RFC4443] does not even specify a Source
      Quench message).

   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] defined the ICMP Source Quench
   message (type 4, code 0), which was meant to provide a mechanism for
   congestion control.  The Host Requirements RFC [RFC1122] stated in
   Section 4.2.3.9 that hosts MUST react to ICMP Source Quench messages
   by slowing transmission on the connection, and further added that the
   RECOMMENDED procedure was to put the corresponding connection in the
   slow-start phase of TCP's congestion control algorithm [RFC5681].

   [RFC1812] noted that research suggested that ICMP Source Quench was
   an ineffective (and unfair) antidote for congestion, and formally
   deprecated the generation of ICMP Source Quench messages by routers,



Gont                      Expires June 24, 2012                 [Page 3]

Internet-Draft      Deprecation of ICMP Source Quench      December 2011


   stating that routers SHOULD NOT send ICMP Source Quench messages in
   response to congestion.

   [RFC5927] discussed the use of ICMP Source Quench messages for
   performing "blind throughput-reduction" attacks, and noted 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.

      It is interesting to note that ICMPv6 [RFC4443] does not specify a
      "Source Quench" message.


3.  Updating RFC 1122

   This document hereby updates Section 3.2.2.3 of [RFC1122] as follows:

      A host MUST NOT send ICMP Source Quench messages.

      If a Source Quench message is received, the IP layer MAY silently
      discard it.

   Section 4.2.3.9 of [RFC1122] is updated as follows:

      TCP MUST silently discard any received ICMP Source Quench
      messages.

   The consensus of the TSV WG was that there are no valid reasons for a
   host to generate or react to an ICMP Source Quench message in the
   current Internet.  The recommendation that a sender "MUST NOT" send
   an ICMP Source Quench message is because there is no known valid
   reason for a host to generate this message.  The only known impact of
   a sender ignoring this requirement is that it may necessarily consume
   network and endpoint resources.  Discarding ICMP Source Quench
   messages at the internet-layer (rather than at the transport layer)
   is a performance optimization that is permitted by this update.


4.  Updating RFC 1812

   This document hereby updates Section 4.3.3.3 of [RFC1812] as follows:








Gont                      Expires June 24, 2012                 [Page 4]

Internet-Draft      Deprecation of ICMP Source Quench      December 2011


      A router MUST ignore any ICMP Source Quench messages it receives.

   The consensus of the TSV WG was that there are no valid reasons for a
   router to react to ICMP Source Quench messages in the current
   Internet.


5.  Clarification for UDP, SCTP, and DCCP

   UDP did not explicitly specify support for ICMP Source Quench
   messages.  Hereby we clarify that UDP end-points MUST silently
   discard received ICMP Source Quench messages.

   It is understood that SCTP and DCCP did not specify support for
   processing received ICMP Source Quench messages.  Hereby we clarify
   that DCCP and SCTP end-points MUST silently discard received ICMP
   Source Quench messages.


6.  General Advice to Transport Protocols

   If a Source Quench message is received by any other transport-
   protocol instance, it MUST be silently ignored.

   The TSV WG is not aware of any use that requires processing of these
   messages, and therefore expects other transports to follow the
   recommendations in Section 3.  Note that for IETF-specified
   transports, this document formally deprecates reaction to ICMP Source
   Quench messages, and that generation of ICMP Source Quench messages
   has been deprecated for both hosts and routers.  Therefore, future
   applications can not expect to receive these messages.


7.  Changing the status of RFC 1016 to Historic

   This document requests the RFC Editor to change the status of
   [RFC1016] to "Historic".


8.  Security Considerations

   ICMP Source Quench messages could be leveraged for performing blind
   throughput-reduction attacks against TCP and similar protocols.  This
   attack vector, along with possible countermeasures, has been
   discussed in great detail in [RFC5927] and [CPNI-TCP].

   Even though sources "MUST NOT" send ICMP Source Quench Message, there
   are no known security issues that result from receipt of this message



Gont                      Expires June 24, 2012                 [Page 5]

Internet-Draft      Deprecation of ICMP Source Quench      December 2011


   because, as noted in [RFC5927] and [CPNI-TCP], virtually all current
   versions of popular TCP implementations already silently ignore ICMP
   Source Quench messages.  This is also the case for SCTP and DCCP
   implementations.  Receivers should not treat reception as an
   exception, error or logged event.  Receipt of an ICMP Source Quench
   message must not be interpreted as an attempt to attack the receiver.

   Silently ignoring ICMP Source Quench messages, as specified in this
   document, eliminates the aforementioned attack vector.

   If deemed necessary, ICMP Source Quench messages could be filtered at
   firewalls.


9.  IANA Considerations

   IANA is requested to mark ICMP type 4 (Source Quench) as "Deprecated"
   in de ICMP Parameters registry [ICMPPARREG] with a reference to this
   document.


10.  Acknowledgements

   The author of this document would like to thank (in alphabetical
   order) Fred Baker, David Black, Scott Bradner, James Carlson, Antonio
   De Simone, Gorry Fairhurst, Alfred Hoenes, Mahesh Jethanandani,
   Carlos Pignataro, Anantha Ramaiah, Randall Stewart, Dan Wing, and
   Andrew Yourtchenko, for providing valuable feedback on earlier
   versions of this document.

   This document has benefited from discussions within the TCPM Working
   Group while working on [RFC5927].


11.  References

11.1.  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.

   [RFC1016]  Prue, W. and J. Postel, "Something a host could do with
              source quench: The Source Quench Introduced Delay
              (SQuID)", RFC 1016, July 1987.




Gont                      Expires June 24, 2012                 [Page 6]

Internet-Draft      Deprecation of ICMP Source Quench      December 2011


   [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.

   [RFC5681]  Allman, M., Paxson, V., and E. Blanton, "TCP Congestion
              Control", RFC 5681, September 2009.

11.2.  Informative References

   [CPNI-TCP]
              CPNI, "Security Assessment of the Transmission Control
              Protocol (TCP)", 2009, <http://www.cpni.gov.uk/Docs/
              tn-03-09-security-assessment-TCP.pdf>.

   [FreeBSD]  The FreeBSD Project, "http://www.freebsd.org".

   [ICMPPARREG]
              Internet Control Message Protocol (ICMP) Parameters,
              "http://www.iana.org/assignments/icmp-parameters".

   [Linux]    The Linux Project, "http://www.kernel.org".

   [NetBSD]   The NetBSD Project, "http://www.netbsd.org".

   [OpenBSD]  The OpenBSD Project, "http://www.openbsd.org".

   [OpenSolaris]
              OpenSolaris, "http://www.opensolaris.org".

   [RFC3168]  Ramakrishnan, K., Floyd, S., and D. Black, "The Addition
              of Explicit Congestion Notification (ECN) to IP",
              RFC 3168, September 2001.

   [RFC4443]  Conta, A., Deering, S., and M. Gupta, "Internet Control
              Message Protocol (ICMPv6) for the Internet Protocol
              Version 6 (IPv6) Specification", RFC 4443, March 2006.

   [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




Gont                      Expires June 24, 2012                 [Page 7]

Internet-Draft      Deprecation of ICMP Source Quench      December 2011


   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], OpenBSD [OpenBSD], and Solaris 10 since
   2005.  Additionally, OpenSolaris [OpenSolaris] has always shipped
   with support for ICMP Source Quench messages disabled.


Appendix B.  Changes from previous versions of the draft (to be removed
             by the RFC Editor before publishing this document as an
             RFC)

B.1.  Changes from draft-ietf-tsvwg-source-quench-01

   o  Changes deprecation of ICMP SQ from "SHOULD NOT" to "MUST NOT" in
      response of feedback from Scott Bradner and the TSV WG.

B.2.  Changes from draft-ietf-tsvwg-source-quench-00

   o  Discusses the motivation for deprecating ICMP Source Quench
      messages (as suggested by Anantha Ramaiah).

   o  Incorporates IANA considerations such that ICMP Source Quench
      messages are deprecated in the corresponding registry.

B.3.  Changes from draft-gont-tsvwg-source-quench-01

   o  Addresses nits and editorial changes suggested by Gorry Fairhurst.

   o  Added the status of Solaris and OpenSolaris to Appendix A.

   o  Document resubmitted as draft-ietf.

B.4.  Changes from draft-gont-tsvwg-source-quench-00

   o  This revision reflects the recent discussion about ICMP Source
      Quench messages on the tsvwg mailing-list.  A detailed list of the
      changes is available at:
      http://www.ietf.org/mail-archive/web/tsvwg/current/msg10407.html












Gont                      Expires June 24, 2012                 [Page 8]

Internet-Draft      Deprecation of ICMP Source Quench      December 2011


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








































Gont                      Expires June 24, 2012                 [Page 9]


Html markup produced by rfcmarkup 1.109, available from https://tools.ietf.org/tools/rfcmarkup/