Microsoft KB Archive/219283

= Using MS-CHAP with RADIUS authentication =

Article ID: 219283

Article Last Modified on 11/1/2006

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APPLIES TO


 * Microsoft Windows NT Server 4.0 Standard Edition
 * Microsoft Routing and Remote Access Service Update for Windows NT Server 4.0

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This article was previously published under Q219283



Important This article contains information about how to modify the registry. Make sure to back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify 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 Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

To enable MS-CHAP with RADIUS authentication, follow these steps to add a registry value:  Start Registry Editor (Regedt32.exe). Locate the following key in the registry:

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

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

DWORD: OfferMSCHAP

Value: 0x00000001

 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.

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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.

Note We recommend that you use MS-CHAP version 2. For more information, visit the following Microsoft Web site:

http://www.microsoft.com/technet/isa/2004/help/FW_MSChap.mspx?mfr=true

Additional query words: mschap

Keywords: kbbug kbfix KB219283

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