Defending against Sequence Number Attacks (RFC6528)
Original Publication Date: 2012-Feb-01
Included in the Prior Art Database: 2012-Feb-02
Internet Society Requests For Comment (RFCs)
F. Gont: AUTHOR [+2]
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.
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
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.
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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 ...