Microsoft KB Archive/934583

= ISA Server 2006 cannot delegate authentication to a back-end server from a published Web server =

Article ID: 934583

Article Last Modified on 10/31/2007

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APPLIES TO


 * Microsoft Internet Security and Acceleration Server 2006 Standard Edition
 * Microsoft Internet Security and Acceleration Server 2006 Enterprise Edition

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SYMPTOMS
Consider the following scenario:
 * You have a Web server that requires Integrated Windows authentication.
 * A back-end server authenticates the Web server by using Integrated Windows authentication. The back-end server can be a computer that is running Microsoft SQL Server, a file server, or another Web server.
 * You publish the Web server in Microsoft Internet Security and Acceleration (ISA) Server 2006.
 * In the Web listener, you set the authentication method to HTTP Authentication, and then you click to select the Basic check box. Or, you set the authentication method to HTML Form Authentication.
 * In the Web publishing rule, you set the Authentication Delegation settings to use the Negotiate (Kerberos/NTLM) authentication method.

In this scenario, the authentication between the Web server and the back-end server fails. ISA Server 2006 cannot delegate authentication to a back-end server from a published Web server. Depending on the Web server configuration, the client user may see the following different symptoms:  If the Web server is configured to return a custom error page, the client user sees this error page. If you apply HTML form authentication as the authentication method, the client user receives the following error message:

You do not have the permissions required to access this Web site. Please contact the Web site administrator.

Then, the client user is redirected to the logon form. If you apply Basic authentication as the authentication method, the client user is repeatedly prompted for user credentials. If the client user closes the dialog box that contains the prompt, the user receives the following error message:

You do not have permission to view this directory or page due to the access control list (ACL) that is configured for this resource on the Web server.

HTTP Error 401.3 - Unauthorized: Access is denied due to an ACL set on the requested resource.





CAUSE
When ISA Server performs Negotiate (Kerberos/NTLM) delegation, ISA Server requests a Kerberos ticket that cannot be delegated. Then, ISA Server uses the ticket to authenticate the published Web server. The published Web server cannot use the ticket to authenticate the back-end server because the ticket cannot be delegated.



RESOLUTION
To resolve this problem, follow these steps:  Apply the hotfix package that is described in the following Microsoft Knowledge Base article:

934587 Description of the ISA Server 2006 hotfix package: March 30, 2007

 Start Notepad.  Copy and then paste the following text into Notepad.  ' ' Copyright (c) Microsoft Corporation. All rights reserved. ' THIS CODE IS MADE AVAILABLE AS IS, WITHOUT WARRANTY OF ANY KIND. THE ENTIRE ' RISK OF THE USE OR THE RESULTS FROM THE USE OF THIS CODE REMAINS WITH THE ' USER. USE AND REDISTRIBUTION OF THIS CODE, WITH OR WITHOUT MODIFICATION, IS ' HEREBY PERMITTED. 

 ' This script sets authentication schemes that ISA will return for Integrated authentication.  Const SE_VPS_GUID = &quot;{143F5698-103B-12D4-FF34-1F34767DEabc}&quot; Const SE_VPS_NAME = &quot;NegotiateDelegationContextReqFlags&quot; Const SE_VPS_VALUE = 1

Sub SetValue

' Create the root object. Dim root ' The FPCLib.FPC root object Set root = CreateObject(&quot;FPC.Root&quot;)

'Declare the other objects that are needed. Dim array      ' An FPCArray object Dim VendorSets ' An FPCVendorParametersSets collection Dim VendorSet  ' An FPCVendorParametersSet object

' Get references to the array object ' and to the network rules collection. Set array = root.GetContainingArray Set VendorSets = array.VendorParametersSets

On Error Resume Next Set VendorSet = VendorSets.Item( SE_VPS_GUID )

If Err.Number <> 0 Then Err.Clear

' Add the item. Set VendorSet = VendorSets.Add( SE_VPS_GUID ) CheckError WScript.Echo &quot;New VendorSet added... &quot; & VendorSet.Name

Else WScript.Echo &quot;Existing VendorSet found... value- &quot; & VendorSet.Value(SE_VPS_NAME) End If

if VendorSet.Value(SE_VPS_NAME) <> SE_VPS_VALUE Then

Err.Clear VendorSet.Value(SE_VPS_NAME) = SE_VPS_VALUE

If Err.Number <> 0 Then CheckError Else VendorSets.Save false, true CheckError

If Err.Number = 0 Then WScript.Echo &quot;Done with &quot; & SE_VPS_NAME & &quot;, saved!&quot; End If       End If    Else WScript.Echo &quot;Done with &quot; & SE_VPS_NAME & &quot;, no change!&quot; End If

End Sub

Sub CheckError

If Err.Number <> 0 Then WScript.Echo &quot;An error occurred: 0x&quot; & Hex(Err.Number) & &quot; &quot; & Err.Description Err.Clear End If

End Sub

SetValue </li> Save the text file as KB934583.vbs, and then copy the file to the computer that is running ISA Server 2006.</li> Double-click the KB934583.vbs file that you saved in step 4.</li></ol>

<div class="status_section">

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

Keywords: kbtshoot kbprb kbexpertiseinter KB934583

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