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Microsoft PPP CHAP Extensions (RFC2433)

IP.com Disclosure Number: IPCOM000003011D
Original Publication Date: 1998-Oct-01
Included in the Prior Art Database: 2000-Sep-13
Document File: 16 page(s) / 32K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

G. Zorn: AUTHOR [+2]

Abstract

The Point-to-Point Protocol (PPP) [1] provides a standard method for transporting multi-protocol datagrams over point-to-point links. PPP defines an extensible Link Control Protocol and a family of Network Control Protocols (NCPs) for establishing and configuring different network-layer protocols.

This text was extracted from a ASCII document.
This is the abbreviated version, containing approximately 9% of the total text.

Network Working Group G. Zorn

Request for Comments: 2433 S. Cobb

Category: Informational Microsoft Corporation

October 1998

Microsoft PPP CHAP Extensions

Status of this Memo

This memo provides information for the Internet community. It does

not specify an Internet standard of any kind. Distribution of this

memo is unlimited.

Copyright Notice

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

IESG Note

The protocol described here has significant vulnerabilities. People

planning on implementing or using this protocol should read section

12, "Security Considerations".

1. Abstract

The Point-to-Point Protocol (PPP) [1] provides a standard method for

transporting multi-protocol datagrams over point-to-point links. PPP

defines an extensible Link Control Protocol and a family of Network

Control Protocols (NCPs) for establishing and configuring different

network-layer protocols.

This document describes Microsoft's PPP CHAP dialect (MS-CHAP), which

extends the user authentication functionality provided on Windows

networks to remote workstations. MS-CHAP is closely derived from the

PPP Challenge Handshake Authentication Protocol described in RFC 1994

[2], which the reader should have at hand.

The algorithms used in the generation of various MS-CHAP protocol

fields are described in an appendix.

2. Introduction

Microsoft created MS-CHAP to authenticate remote Windows

workstations, providing the functionality to which LAN-based users

are accustomed while integrating the encryption and hashing

algorithms used on Windows networks.

Where possible, MS-CHAP is consistent with standard CHAP. Briefly,

the differences between MS-CHAP and standard CHAP are:

* MS-CHAP is enabled by negotiating CHAP Algorithm 0x80 in LCP

option 3, Authentication Protocol.

* The MS-CHAP Response packet is in a format designed for

compatibility with Microsoft's Windows NT 3.5, 3.51 and 4.0, and

Windows95 networking products. The MS-CHAP format does not

require the authenticator to store a clear-text or reversibly

encrypted password.

* MS-CHAP provides authenticator-controlled authentication retry

and password changing mechanisms.

* MS-CHAP defines a set of reason-for-failure codes returned in

the Failure packet Message field.

3. Specification of Requirements

In this document, the key words "MAY", "MUST, "MUST ...