Browse Prior Art Database

Protection of BGP Sessions via the TCP MD5 Signature Option (RFC2385)

IP.com Disclosure Number: IPCOM000002957D
Original Publication Date: 1998-Aug-01
Included in the Prior Art Database: 2000-Sep-13
Document File: 5 page(s) / 11K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

A. Heffernan: AUTHOR

Abstract

This memo describes a TCP extension to enhance security for BGP. It defines a new TCP option for carrying an MD5 [RFC1321] 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.

This text was extracted from a ASCII Text document.
This is the abbreviated version, containing approximately 26% of the total text.

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 [RFC1321] 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

during the lifetime of a particular connection so long as this change

was synchronized on both ends (although retransmission can become

problematical in some TCP implementations with changing passwords).

Finally, there is no negotiation for the use of this option in a

connection, rather it is purely a matter of site policy whether or

not its connections use the option.

2.0 Proposal

Every segment sent on a TCP connection to be protected against

spoofing will contain the 16-byte MD5 digest produced by applying the

MD5 algorithm to these items in the following order:

1. the TCP pseudo-header (in the order: source IP address,

destination IP address, zero-padded protocol number, and

segment length)

2. the TCP header, excluding options, and assuming a checksum of

zero

3. the TCP segment data (if any)

4. an independently-specified key or password, known to both TCPs

and presumably connection-specific

The header and pseudo-header are in network byte order. The nature

of the ke...