Microsoft KB Archive/240870

= "Access Denied" When an SP5 RRAS Client Access an SP5 RRAS Server with OfferMSCHAP =

Article ID: 240870

Article Last Modified on 11/1/2006

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APPLIES TO


 * Microsoft Windows NT Server 4.0 Standard Edition
 * Microsoft Windows NT 4.0 Service Pack 5
 * Microsoft Windows NT Server 4.0 Enterprise Edition
 * Microsoft Windows NT 4.0 Service Pack 4
 * Microsoft Windows NT 4.0 Service Pack 5

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This article was previously published under Q240870



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 that is described in this article. Apply it only to computers that are 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 about support costs, visit the following Microsoft Web site:

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

NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual 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 that this is 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:

189594 RRAS Upgrade for WinNT Server 4.0 Hotfix Pack 3.0 Release Notes

189595 Performance and Security Upgrade for WinNT 4.0 Release Notes

222060 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

Keywords: kbbug kbfix kbqfe kbhotfixserver KB240870

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