Microsoft KB Archive/220965

= XWEB: Outlook Web Access NT Challenge Response Not Working as Expected =

Article ID: 220965

Article Last Modified on 10/28/2006

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APPLIES TO


 * Microsoft Outlook Web Access 5.5
 * Microsoft Exchange Server 5.5 Service Pack 1
 * Microsoft Exchange Server 5.5 Service Pack 2
 * Microsoft Exchange Server 5.5 Service Pack 3
 * Microsoft Exchange Server 5.5 Standard Edition

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This article was previously published under Q220965





SYMPTOMS
When you attempt to log onto Outlook Web Access (OWA) after installing Exchange Server version 5.5 or an Exchange Server 5.5 service pack, you will be prompted for credentials, even though Internet Information Server has been set to use NT Challenge Response (NTCR) for authentication. After entering your Windows NT credentials, OWA should function.



CAUSE
NT Challenge/Response authentication is no longer enabled in the security authentication methods for the IIS server. By default, installing Exchange OWA on an IIS 4.0 server will enable Basic (clear text) authentication and disable NTCR. This only occurs with IIS 4.0 installations, and not with IIS 3.0.



WORKAROUND
If IIS and Exchange Server are installed on the same physical computer, you can re-enable NT Challenge Response if you want it. If security is an issue, you may want to consider installing Secure Sockets Layer(SSL). For more information on enabling SSL, see the documentation for IIS version 4.0.



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

Keywords: kbbug kbpending KB220965

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