How to Force Routing and Remote Access to Use PAP

 Last reviewed: September 3, 1997
Article ID: Q172216
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 4.0

SUMMARY

This article discusses the method for forcing a Routing and Remote Access (RRAS) server for Windows NT 4.0 to authenticate RAS clients using PAP instead of CHAP, SPAP, or MS-CHAP. This may be necessary, depending on your RAS clients or some third-party authentication solutions.

MORE INFORMATION

If your RRAS server is configured to "Allow any authentication including clear text," a RAS client is able to connect with PAP, SPAP, CHAP, or MS- CHAP depending on what the client supports. Normally, a Microsoft RAS client will attempt to connect with CHAP or MS-CHAP, if that is valid for the RAS server to which it is connecting.

To force a RAS client to use PAP, you must delete the SPAP and CHAP registry keys from your RAS Server using the following steps:

WARNING: Using Registry Editor incorrectly can cause serious, system-wide problems that may require you to reinstall Windows NT to correct them. Microsoft cannot guarantee that any problems resulting from the use of Registry Editor can be solved. Use this tool at your own risk.

  1. Start Registry Editor (Regedt32.exe).

  2. Go to the following subkey: 

          HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\RasMan\PPP

  3. Click SPAP, click Edit, and click Delete.

  4. Click Yes to confirm the deletion.

  5. Click CHAP, click Edit, and click Delete.

  6. Click Yes to confirm the deletion.

  7. Close Registry Editor and stop and restart the Routing and Remote Access Service.

NOTE: This will not work on normal Windows NT RAS servers, only Windows NT 4.0 RAS servers that have Routing and Remote Access installed. If you delete these registry keys on a normal RAS server, the RAS services will fail to start after you restart.

The following two scenarios require the above steps to force RAS clients to use PAP authentication:

  • You are using a PPP client that can only use PAP, but does not notify the RAS server that it needs to use PAP during the LCP negotiation.

    -or-

  • You are using the new Radius client included in the Routing and Remote Access Service Update. Many Radius servers do not accept the attribute 60 CHAP Challenge that the Radius Client sends to the Radius server when authenticating a RAS client using CHAP. This is a valid attribute according to RFC 2058: "Remote Authentication Dial In User Service (RADIUS)"; however, many older Radius servers cannot handle this newer attribute.

For additional information, please see the following article(s) in the Microsoft Knowledge Base: 

   ARTICLE-ID: Q136634
   TITLE     : Remote Access Services Authentication Summary

Keywords          : nthowto ntnetserv ntrouter NTSrv kbnetwork
Version           : WinNT:4.0
Platform          : winnt
Issue type        : kbhowto kbinfo
Solution Type     : kbworkaround

================================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.

Last reviewed: September 3, 1997
© 1998 Microsoft Corporation. All rights reserved. Terms of Use.