The Web filter code receives an internal error message when you use an ISA Server 2000 ISAPI Web filter to change the special request headers on the SF_NOTIFY_AUTH_COMPLETE notification. (897719)


The information in this article applies to:

  • Microsoft Internet Security and Acceleration Server 2000
Important This article contains information about how to modify the registry. Make sure to back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows registry

SYMPTOMS

You are using a Web filter that uses the Microsoft Internet Security and Acceleration (ISA) Server 2000 Internet Server API (ISAPI) filter model. When you try to use the Web filter to change the special request headers on the SF_NOTIFY_AUTH_COMPLETE notification, the Web filter code receives an internal error message that is similar to the following:
Error 87 - "the parameter is incorrect"

CAUSE

The ISA Server 2000 ISAPI filter model does not enable the SetHeader function to change the Method, URL, and HTTP Version special request headers on the SF_NOTIFY_AUTH_COMPLETE notification. This behavior is by design and makes sure that the ISA Server 2000 policy check is not affected by changes in the special request header values.

RESOLUTION

Hotfix information

A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next Internet Security and Acceleration Server 2000 service pack that contains this hotfix.

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

http://support.microsoft.com/contactus/?ws=support

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 usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

Prerequisites

ISA Server 2000 Service Pack 2

Restart requirement

You do not have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.
   Date         Time   Version        Size     File name
   --------------------------------------------------------- 
   25-Apr-2005  08:07  3.0.1200.415   401,912  W3proxy.exe

MORE INFORMATION

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

To enable the SetHeader function to change the Method, URL, and HTTP Version special request headers on the SF_NOTIFY_AUTH_COMPLETE notification, follow these steps after you install the hotfix:
  1. Turn on the Ask unauthenticated users for identification option on the incoming Web request listener for Web publishing rules or on the outgoing Web request listener for outgoing Web proxy requests.

    To turn on the Ask unauthenticated users for identification option on the incoming Web request listener for Web publishing rules, follow these steps:
    1. Start the ISA Management console. To do this, click Start, point to Programs, point to Microsoft ISA Server, and then click ISA Management.
    2. Right-click the server or the array name, and then click Properties.
    3. Click the Incoming Web Requests tab.
    4. Click to select the Ask unauthenticated users for identification check box, and then click OK.
    To turn on the Ask unauthenticated users for identification option on the outgoing Web request listener for outgoing Web proxy requests, follow these steps:
    1. Start the ISA Management console. To do this, click Start, point to Programs, point to Microsoft ISA Server, and then click ISA Management.
    2. Right-click the server or array name, and then click Properties.
    3. Click the Outgoing Web Requests tab.
    4. Click to select the Ask unauthenticated users for identification check box, and then click OK.
  2. Add the AllowRequestLineChangesInAuthComplete registry value. To do this, follow these steps:
    1. Click Start, click Run, type regedit, and then click OK.
    2. Locate and then click the following registry key:

      HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W3Proxy\Parameters

    3. On the Edit menu, point to New, and then click DWORD Value.
    4. Type AllowRequestLineChangesInAuthComplete, and then press ENTER.
    5. Right-click AllowRequestLineChangesInAuthComplete, and then click Modify.
    6. Type 1 in the Value data box, and then click OK.
    7. Quit Registry Editor.

    Note You must restart the ISA Server Web proxy service for the AllowRequestLineChangesInAuthComplete registry value to take effect.
When you use a Web filter instead of the ISA Server policy engine to implement policy checks, the Web filter may have to change the special request headers on the SF_NOTIFY_AUTH_COMPLETE notification to improve scalability.

When a Web filter generates a client response, the client-to-ISA Server connection is ended. This behavior is by design. If Integrated Windows authentication is used, the number of connections that are opened and closed may increase. This behavior increases the authentication overhead.

When a Web filter issues a re-direct to the client, it may be more efficient for the Web filter to re-write the requested URL and to enable ISA Server to retrieve the URL on behalf of the client. This behavior reduces the number of roundtrips made by the client. This behavior also maintains the client-to-ISA Server TCP connection and any authentication context that was previously negotiated on that connection. In this scenario, the original URL can be re-written on the SF_NOTIFY_LOG notification so that the original URL is logged if it is required. Implement this functionality in a Web filter that filters URLs if the following conditions are true:
  • The Web filter performs access control that is based on a database of categorizeds URLs.
  • The Web filter wants to re-direct the user to a block page if a request is not permitted.


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

824684 Description of the standard terminology that is used to describe Microsoft software updates

Modification Type:MinorLast Reviewed:7/24/2006
Keywords:kbQFE kbfix kbbug kbpubtypekc KB897719 kbAudITPRO
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