Microsoft Vendor-specific RADIUS Attributes (RFC2548)
Original Publication Date: 1999-Mar-01
Included in the Prior Art Database: 2019-Feb-11
Internet Society Requests For Comment (RFCs)
This document describes the set of Microsoft vendor-specific RADIUS attributes. This memo provides information for the Internet community.
Network Working Group G. Zorn Request for Comments: 2548 Microsoft Corporation Category: Informational March 1999
Microsoft Vendor-specific RADIUS Attributes
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 (C) The Internet Society (1999). All Rights Reserved.
This document describes the set of Microsoft vendor-specific RADIUS attributes. These attributes are designed to support Microsoft proprietary dial-up protocols and/or provide support for features which is not provided by the standard RADIUS attribute set . It is expected that this memo will be updated whenever Microsoft defines a new vendor-specific attribute, since its primary purpose is to provide an open, easily accessible reference for third-parties wishing to interoperate with Microsoft products.
1. Specification of Requirements
In this document, the key words "MAY", "MUST, "MUST NOT", "optional", "recommended", "SHOULD", and "SHOULD NOT" are to be interpreted as described in .
The following sections describe sub-attributes which may be transmitted in one or more RADIUS attributes of type Vendor-Specific . More than one sub-attribute MAY be transmitted in a single Vendor-Specific Attribute; if this is done, the sub-attributes SHOULD be packed as a sequence of Vendor-Type/Vendor-Length/Value triples following the inital Type, Length and Vendor-ID fields. The Length field of the Vendor-Specific Attribute MUST be set equal to the sum of the Vendor-Length fields of the sub-attributes contained in the Vendor-Specific Attribute, plus six. The Vendor-ID field of the Vendor-Specific Attribute(s) MUST be set to decimal 311 (Microsoft).
Zorn Informational [Page 1]
RFC 2548 Microsoft Vendor-specific RADIUS Attributes March 1999
2.1. Attributes for Support of MS-CHAP Version 1
Microsoft created Microsoft Challenge-Handshake Authentication Protocol (MS-CHAP)  to authenticate remote Windows workstations, providing the functionality to which LAN-based users are accustomed. Where possible, MS-CHAP is consistent with standard CHAP , and the differences are easily modularized. 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 Windows NT 3.5, 3.51 and 4.0, Microsoft Windows95, and Microsoft LAN Manager 2.x networking products. The MS-CHAP format does not require the authenticator to store a clear-text or reversibly encrypted password.
* MS-CHAP provides an authenticator-controlled authentication retry mechanism.
* MS-CHAP provides an authenticator-controlled password changing mechanism.
* MS-CHAP defines an extended set of reason-for-failure codes, returned in the Failure packet Message field.