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Q168667: RADIUS: Remote Authentication Dial In User Service

Article: Q168667
Product(s): Microsoft Windows NT
Version(s): winnt:4.0
Operating System(s): 
Keyword(s): kbnetwork
Last Modified: 10-AUG-2001

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The information in this article applies to:

- Microsoft Windows NT Server version 4.0 
- Microsoft Routing and Remote Access Service Update for Windows NT Server version 4.0 
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SUMMARY
=======

RADIUS is an acronym for Remote Authentication Dial In User Service. RADIUS
defines a popular standard used for maintaining and managing remote user
authentication and validation. The new Routing and Remote Access Service (RRAS)
can operate as a RADIUS client. This allows RAS clients and dial-up routers to
be authenticated against a RADIUS server.

MORE INFORMATION
================

RADIUS is defined by RFC 2138. The following is an excerpt from RFC 2138:

  Key features of RADIUS are:

  Client/Server Model

  A Network Access Server (NAS) operates as a client of RADIUS. The client is
  responsible for passing user information to designated RADIUS servers, and
  then acting on the response which is returned.

  RADIUS servers are responsible for receiving user connection requests,
  authenticating the user, and then returning all configuration information
  necessary for the client to deliver service to the user.

  A RADIUS server can act as a proxy client to other RADIUS servers or other
  kinds of authentication servers.

  Network Security

  Transactions between the client and RADIUS server are authenticated through
  the use of a shared secret, which is never sent over the network. In
  addition, any user passwords are sent encrypted between the client and RADIUS
  server, to eliminate the possibility that someone snooping on an unsecure
  network could determine a user's password.

  Flexible Authentication Mechanisms

  The RADIUS server can support a variety of methods to authenticate a user.
  When it is provided with the user name and original password given by the
  user, it can support PPP PAP, CHAP, UNIX login, and other authentication
  mechanisms.

  Extensible Protocol

  All transactions are comprised of variable length Attribute-Length-Value
  3-tuples. New attribute values can be added without disturbing existing
  implementations of the protocol.

Routing and Remote Access RADIUS client supports the following options:

  Acct-Session-Id
  Acct-Session-Time
  Acct-Status-Type
  Callback-Number
  Framed-IP-Address
  Framed-Protocol
  Idle-Timeout
  NAS-Identifier
  NAS-Port
  NAS-Port-Type
  Port-Limit
  Session-Timeout
  User-Name

To enable all of the above RADIUS functionality in RRAS, please obtain the latest
Hotfix Pack for RRAS. For additional information about the Routing and Remote
Access Hotfix Pack 2.0, see the following article in the Microsoft Knowledge
Base:

  Q168469 RRAS Upgrade for WinNT Server 4.0 Hotfix Pack 2.0 Release Notes

The Radius server is included with the Windows NT 4.0 Option Pack

Additional query words: attribute

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Keywords          : kbnetwork 
Technology        : kbWinNTsearch kbWinNT400search kbWinNTSsearch kbWinNTS400search kbWinNTS400 kbAudDeveloper kbRRASNTSearch kbRRASNT400
Version           : winnt:4.0

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