Microsoft KB Archive/922851

= You receive a blank page when your Web browser submits a POST request to an ASP Web site over an ISA Server 2004 access rule that requires client authentication =

Article ID: 922851

Article Last Modified on 12/4/2007

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APPLIES TO


 * Microsoft Internet Security and Acceleration Server 2004 Standard Edition
 * Microsoft Internet Security and Acceleration Server 2004 Enterprise Edition

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SYMPTOMS
When your Web browser program submits a POST request to an Active Server Pages (ASP) Web site through Microsoft Internet Security and Acceleration (ISA) Server 2004, you may receive a blank page in response.



CAUSE
This problem occurs if the following conditions are true:
 * The following rules are configured in ISA Server 2004:
 * A Content Type rule that applies to HTTP traffic is configured. This Content Type rule is evaluated when the POST request is processed.
 * An access rule that enables the POST request to be submitted to the Web server is configured. This access rule requires the client to authenticate.
 * The client sends the POST request to ISA Server 2004 over an unauthenticated TCP connection.
 * The POST request that the client makes is an HTTP 1.1 request.
 * The Web server sends back an &quot;HTTP 100 Continue&quot; response before it sends the &quot;HTTP 200&quot; response together with the response data.

In this scenario, ISA Server 2004 relays the Web server's &quot;HTTP 100 Continue&quot; response to the client as expected. However, ISA Server 2004 incorrectly does not send the &quot;HTTP 407 Proxy Authentication Required&quot; request to the client.



RESOLUTION
To resolve this problem, apply the hotfix that is mentioned in the following Microsoft Knowledge Base article:

922792 Description of the ISA Server 2004 hotfix package: July 13, 2006



WORKAROUND
To work around this problem, configure the client Web browser program to use HTTP 1.0 through proxy connections. To do this in Microsoft Internet Explorer, follow these steps:
 * 1) Start Internet Explorer.
 * 2) On the Tools menu, click Internet Options.
 * 3) In the Internet Options dialog box, click the Advanced tab.
 * 4) Under HTTP 1.1 settings, click to clear the Use HTTP 1.1 through proxy connections check box, and then click OK.



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.



MORE INFORMATION
For more information, click the following article number to view the article in the Microsoft Knowledge Base:

885957 How to install ISA Server hotfixes and updates

Additional query words: 407 Authenticate

Keywords: kbtshoot kbbug kbfix kbfirewall kbprb KB922851

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