Q240870: "Access Denied" When SP5 RRAS Client Access SP5 RRAS Server

Article: Q240870
Product(s): Microsoft Windows NT
Version(s): 4.0,4.0 SP4,4.0 SP5
Operating System(s): 
Keyword(s): kbWinNT400PreSP7Fix
Last Modified: 08-MAY-2002

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The information in this article applies to:

- Microsoft Windows NT Server versions 4.0, 4.0 SP5 
- Microsoft Windows NT Server, Enterprise Edition versions 4.0, 4.0 SP4, 4.0 SP5 
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SYMPTOMS
========

When you attempt to make a Point-to-Point Tunneling Protocol (PPTP) connection
from a Windows NT 4.0 Service Pack 5 (SP5) client to a Windows NT 4.0 SP5 PPTP
server running Remote Access Services (RAS) or Routing and Remote Access
Services (RRAS), the initial authentication attempt may not succeed and may
display an "Error 5: Access Denied" error message. This problem can also occur
if RRAS is configured to forward Microsoft Challenge-Handshake Authentication
Protocol (MS-CHAP) version 2 authentication requests to a Remote Authentication
Dial-In User Service (RADIUS) server.

CAUSE
=====

This behavior is caused by a problem in Rasrad.dll, in which the challenge from
the RRAS server to the client is incorrectly formatted. This problem results in
the client rejecting the challenge and disconnecting the session.

RESOLUTION
==========

A supported fix is now available from Microsoft, but it is only intended to
correct the problem described in this article and should be applied only to
systems experiencing this specific problem.

To resolve this problem, contact Microsoft Product Support Services to obtain the
fix. For a complete list of Microsoft Product Support Services phone numbers and
information on support costs, please go to the following address on the World
Wide Web:

  http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS

NOTE: In special cases, charges that are normally incurred for support calls may
be canceled, if a Microsoft Support Professional determines that a specific
update will resolve your problem. Normal support costs will apply to additional
support questions and issues that do not qualify for the specific update in
question.

The English-language version of this fix should have the following file
attributes or later:

  Date      Time    Version      Size    File name     Platform
  -------------------------------------------------------------
  07/27/99  09:28a                41,744 Rasrad.dll    x86
  07/27/99  09:26a                68,368 Rasrad.dll    Alpha



STATUS
======

Microsoft has confirmed this to be a problem in the Microsoft products that are
listed at the beginning of this article.

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

For additional information, click the article numbers below to view the articles
in the Microsoft Knowledge Base:

  Q189594 RRAS Upgrade for WinNT Server 4.0 Hotfix Pack 3.0 Release Notes

  Q189595 Performance and Security Upgrade for WinNT 4.0 Release Notes

  Q222060 Err Msg: 'Error 5: Access Denied' When Using PPTP with RAS

To enable MS-CHAP with RADIUS authentication, you must add the following registry
value:

  Key: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Rasman\PPP\CHAP

  Value Name: OfferMSCHAP
  Type: DWORD
  Data Value: 0x00000001 - Once this is enabled, every incoming Point-to-Point
  Protocol (PPP) connection is offered MS-CHAP, and MS-CHAP is used to
  authenticate each PPP user against the RADIUS server that your RAS server is
  using.

Additional query words: IAS mschap

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Keywords          : kbWinNT400PreSP7Fix 
Technology        : kbWinNTsearch kbWinNT400search kbWinNTSsearch kbWinNTSEntSearch kbWinNTSEnt400sp5 kbWinNTSEnt400sp4 kbWinNTSEnt400 kbWinNTS400sp5 kbWinNTS400search kbWinNTS400
Version           : :4.0,4.0 SP4,4.0 SP5
Hardware          : ALPHA x86
Issue type        : kbbug
Solution Type     : kbfix

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