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Defending against Sequence Number Attacks (RFC6528)

IP.com Disclosure Number: IPCOM000214675D
Original Publication Date: 2012-Feb-01
Included in the Prior Art Database: 2012-Feb-02
Document File: 24 page(s) / 27K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

F. Gont: AUTHOR [+2]

Abstract

For a long time, the Internet has experienced a number of off-path attacks against TCP connections. These attacks have ranged from trust-relationship exploitation to denial-of-service attacks [CPNI-TCP]. Discussion of some of these attacks dates back to at least 1985, when Morris [Morris1985] described a form of attack based on guessing what sequence numbers TCP [RFC0793] will use for new connections between two known end-points.

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Internet Engineering Task Force (IETF)                           F. Gont Request for Comments: 6528                        SI6 Networks / UTN-FRH Obsoletes: 1948                                              S. Bellovin Updates: 793                                         Columbia University Category: Standards Track                                  February 2012 ISSN: 2070-1721

                Defending against Sequence Number Attacks

Abstract

   This document specifies an algorithm for the generation of TCP    Initial Sequence Numbers (ISNs), such that the chances of an off-path    attacker guessing the sequence numbers in use by a target connection    are reduced.  This document revises (and formally obsoletes) RFC    1948, and takes the ISN generation algorithm originally proposed in    that document to Standards Track, formally updating RFC 793.

Status of This Memo

   This is an Internet Standards Track document.

   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).  Further information on    Internet Standards is available in 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/rfc6528.

Copyright Notice

   Copyright (c) 2012 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.

 Gont & Bellovin              Standards Track                    [Page 1]
 RFC 6528        Defending against Sequence Number Attacks  February 2012

 Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2    2.  Generation of Initial Sequence Numbers . . . . . . . . . . . .  3    3.  Proposed Initial Sequence Number Generation Algorithm  . . . .  4    4.  Security Considerations  . . . . . . . . . . . . . . . . . . .  5    5.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . .  6 ...