RFC 2385 (rfc2385) - Page 1 of 6

Protection of BGP Sessions via the TCP MD5 Signature Option

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Network Working Group                                       A. Heffernan
Request for Comments: 2385                                 cisco Systems
Category: Standards Track                                    August 1998


      Protection of BGP Sessions via the TCP MD5 Signature Option

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (1998).  All Rights Reserved.

IESG Note

   This document describes currrent existing practice for securing BGP
   against certain simple attacks.  It is understood to have security
   weaknesses against concerted attacks.

Abstract

   This memo describes a TCP extension to enhance security for BGP.  It
   defines a new TCP option for carrying an MD5 [RFC 1321] digest in a
   TCP segment.  This digest acts like a signature for that segment,
   incorporating information known only to the connection end points.
   Since BGP uses TCP as its transport, using this option in the way
   described in this paper significantly reduces the danger from certain
   security attacks on BGP.

1.0  Introduction

   The primary motivation for this option is to allow BGP to protect
   itself against the introduction of spoofed TCP segments into the
   connection stream.  Of particular concern are TCP resets.

   To spoof a connection using the scheme described in this paper, an
   attacker would not only have to guess TCP sequence numbers, but would
   also have had to obtain the password included in the MD5 digest.
   This password never appears in the connection stream, and the actual
   form of the password is up to the application.  It could even change





Heffernan                   Standards Track
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