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ICMP Attacks against TCP
RFC 5927

Document type: RFC - Informational (July 2010; No errata)
Document stream: IETF
Last updated: 2013-03-02
Other versions: plain text, pdf, html

IETF State: (None)
Consensus: Unknown
Document shepherd: No shepherd assigned

IESG State: RFC 5927 (Informational)
Responsible AD: Lars Eggert
Send notices to: tcpm-chairs@tools.ietf.org, draft-ietf-tcpm-icmp-attacks@tools.ietf.org

Internet Engineering Task Force (IETF)                           F. Gont
Request for Comments: 5927                                       UTN/FRH
Category: Informational                                        July 2010
ISSN: 2070-1721

                        ICMP Attacks against TCP

Abstract

   This document discusses the use of the Internet Control Message
   Protocol (ICMP) to perform a variety of attacks against the
   Transmission Control Protocol (TCP).  Additionally, this document
   describes a number of widely implemented modifications to TCP's
   handling of ICMP error messages that help to mitigate these issues.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc5927.

Gont                          Informational                     [Page 1]
RFC 5927                ICMP Attacks against TCP               July 2010

Copyright Notice

   Copyright (c) 2010 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
   described in the Simplified BSD License.

   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

Gont                          Informational                     [Page 2]
RFC 5927                ICMP Attacks against TCP               July 2010

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Background . . . . . . . . . . . . . . . . . . . . . . . . . .  5
     2.1.  The Internet Control Message Protocol (ICMP) . . . . . . .  5
       2.1.1.  ICMP for IP version 4 (ICMPv4) . . . . . . . . . . . .  5
       2.1.2.  ICMP for IP version 6 (ICMPv6) . . . . . . . . . . . .  6
     2.2.  Handling of ICMP Error Messages  . . . . . . . . . . . . .  6
     2.3.  Handling of ICMP Error Messages in the Context of IPsec  .  7
   3.  Constraints in the Possible Solutions  . . . . . . . . . . . .  8
   4.  General Counter-Measures against ICMP Attacks  . . . . . . . . 10
     4.1.  TCP Sequence Number Checking . . . . . . . . . . . . . . . 10
     4.2.  Port Randomization . . . . . . . . . . . . . . . . . . . . 11
     4.3.  Filtering ICMP Error Messages Based on the ICMP Payload  . 11
   5.  Blind Connection-Reset Attack  . . . . . . . . . . . . . . . . 12
     5.1.  Description  . . . . . . . . . . . . . . . . . . . . . . . 12
     5.2.  Attack-Specific Counter-Measures . . . . . . . . . . . . . 13
   6.  Blind Throughput-Reduction Attack  . . . . . . . . . . . . . . 16
     6.1.  Description  . . . . . . . . . . . . . . . . . . . . . . . 16
     6.2.  Attack-Specific Counter-Measures . . . . . . . . . . . . . 16
   7.  Blind Performance-Degrading Attack . . . . . . . . . . . . . . 16
     7.1.  Description  . . . . . . . . . . . . . . . . . . . . . . . 16
     7.2.  Attack-Specific Counter-Measures . . . . . . . . . . . . . 18
     7.3.  The Counter-Measure for the PMTUD Attack in Action . . . . 22
       7.3.1.  Normal Operation for Bulk Transfers  . . . . . . . . . 22
       7.3.2.  Operation during Path-MTU Changes  . . . . . . . . . . 24

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