FIX: Problems with Web Browser if ISA Server 2000 Is Chained to an Upstream Web Proxy Server (317822)


The information in this article applies to:

  • Microsoft Internet Security and Acceleration Server 2000
This article was previously published under Q317822
IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry

SYMPTOMS

If Internet Security and Acceleration (ISA) Server 2000 is chained to an upstream Web proxy server, you may experience unexpected delays, incomplete pages, random authentication warning messages, and so forth, when you browse the Web.

This behavior does not occur if the upstream proxy server requires NTLM authentication and the routing rule on the downstream server is configured to provide Integrated Authentication credentials to the upstream Web proxy server.

CAUSE

This behavior can occur if all of the following conditions are true:
  • The downstream ISA Server computer is configured to require integrated authentication (NTLM).

    -and-
  • The upstream Web proxy server is not configured to require authentication (anonymous).

    -and-
  • You are using Internet Explorer as your client browser.
Under certain circumstances, Internet Explorer sends an extraneous NTLM authentication header on a connection that has already been authenticated with the downstream ISA Server computer by using integrated authentication. This may cause the downstream ISA Server computer to pass those credentials to the upstream Web proxy server. Because these credentials are for the downstream ISA Server computer, the upstream proxy server may return unexpected delays or responses because it is unable to process the NTLM credentials. The downstream ISA Server computer then passes this HTTP response back to the Web browser, resulting in unexpected delays, authentication warning messages, or other effects on the client computer (running Internet Explorer).

RESOLUTION

Note that you must have ISA Server 2000 Service Pack 1 (SP1) installed on your computer before you apply the following fix.

For additional information about how to obtain ISA Server 2000 SP1, click the article number below to view the article in the Microsoft Knowledge Base:

313139 How to obtain the Latest Internet Security and Acceleration Server 2000 Service Pack

A supported fix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Apply it only to computers that are experiencing this specific problem. This fix may receive additional testing. Therefore, if you are not severely affected by this problem, Microsoft recommends that you wait for the next %1 that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS

NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The typical support costs will apply to additional support questions and issues that do not qualify for the specific update in question.


The English-language version of this fix should have the following file attributes or later: 
   Date        Time      Version       Size     File name  
   --------------------------------------------------------
   27-Feb-2002 14:10:00  3.0.1200.170  383,760  W3proxy.exe

STATUS

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

MORE INFORMATION

WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

To implement the functionality in this fix and then enable it, follow these steps after you have installed the fix:
  1. Stop the Web Proxy service.
  2. Start Registry Editor.
  3. Locate and select the following registry key:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W3Proxy\Parameters

  4. Create a new DWORD value named RemoveAllProxyAuthorization. Give this new value a data value of 1.
  5. Restart the Web Proxy service.
To revert to the original configuration, either remove the RemoveAllProxyAuthorization registry value or change its data value to 0 (zero). After you make either change, restart the Web Proxy service.

REFERENCES

For additional information, click the article numbers below to view the articles in the Microsoft Knowledge Base:

297080 Incomplete HTML Pages and Random Authentication Prompts If ISA Server Is Chained to Upstream Proxy

312176 Heavy NTLM Authentication Traffic Occurs Between Internet Explorer and the Proxy Server

Modification Type:MajorLast Reviewed:4/7/2006
Keywords:kbQFE KBHotfixServer kbbug kbfix KB317822
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