Using MS-CHAP with RADIUS Authentication (219283)



The information in this article applies to:

  • Microsoft Windows NT Server 4.0
  • Microsoft Routing and Remote Access Service Update for Windows NT Server 4.0

This article was previously published under Q219283

IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry

SYMPTOMS

Microsoft Windows NT Routing and Remote Access Server does not offer MS-CHAP authentication when used as a Remote Authentication Dial-In User Service (RADIUS) client.

CAUSE

This is by design because several third-party RADIUS servers do not support MS-CHAP authentication.

RESOLUTION

WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

To enable MS-CHAP with RADIUS authentication, you must add a registry value:
  1. Start Registry Editor (Regedt32.exe).
  2. Locate the following key in the registry:

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

  3. On the Edit menu, click Add Value, and then add the following registry value:

    DWORD: OfferMSCHAP
    Value: 0x00000001

  4. Quit Registry Editor.
After this key is enabled, every incoming PPP connection may be offered MS-CHAP, and MS-CHAP may be used to authenticate each PPP user against the Radius server that your RAS server is using.

STATUS

This behavior is by design.

MORE INFORMATION

Set the registry key located in the "Resolution" section to use MS-CHAP authentication when you use the Microsoft Windows NT Routing and Remote Access Server with either Microsoft RADIUS Server or a third-party Radius server that can offer MS-CHAP authentication.

Modification Type:MajorLast Reviewed:6/11/2002
Keywords:kbbug KB219283