Microsoft KB Archive/917557

= FIX: You may experience slow performance when you use Integrated Windows authentication together with the Kerberos authentication protocol in IIS 6.0 =

Article ID: 917557

Article Last Modified on 12/3/2007

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APPLIES TO


 * Microsoft Internet Information Services 6.0

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Important This article contains information about how to modify the registry. Make sure that you 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 may experience slow performance on a computer that is running Microsoft Internet Information Services (IIS) 6.0. This problem occurs when the following conditions are true:
 * You use Integrated Windows authentication together with IIS 6.0.
 * You use the Kerberos authentication protocol to authenticate the user on the Web site.

Note Visitors to a Web site that is hosted on the computer may also experience slow performance. This problem is more likely to occur if the visitors have limited bandwidth.



CAUSE
When you use the Kerberos authentication protocol, IIS 6.0 requires the client to be reauthenticated for each HTTP request. This behavior causes an increase in network traffic.

This behavior differs from Microsoft Internet Information Services (IIS) 5.0. In IIS 5.0, a client that is authenticated by Kerberos after an initial HTTP request stays authenticated for the duration of the HTTP Keep-Alive session.



Service pack information
To resolve this problem, obtain the latest service pack for Windows Server 2003. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

889100 How to obtain the latest service pack for Windows Server 2003

Prerequisites
You must have Windows Server 2003 Service Pack 1 (SP1) installed to apply this hotfix.

Registry 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 the operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

After you apply this hotfix, you must add and configure the EnableKerbAuthPersist registry value. To do this, follow these steps:  Click Start, click Run, type regedit, and then click OK. Locate and then click the following registry subkey:

 On the Edit menu, point to New, and then click DWORD Value. Type EnableKerbAuthPersist for the entry name, and then press ENTER. Right-click EnableKerbAuthPersist, and then click Modify. In the Value data box, type 1 to enable the hotfix, and then click OK.

Note To return the IIS service to the default behavior, type a non-zero value other than 1.</li> Exit Registry Editor.</li> Restart the IIS service. To do this, follow these steps: <ol style="list-style-type: lower-alpha;"> Click Start, click Run, type cmd, and then click OK.</li> Type the following commands. Press ENTER after each command:

net stop iisadmin

net start iisadmin

</li></ol> </li></ol>

Restart requirement
If the IIS service is running when you apply this hotfix, you must restart the IIS service.

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 item in Control Panel.

Windows Server 2003, x86
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STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section. This problem was first corrected in Windows Server 2003 Service Pack 2.

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MORE INFORMATION
After you enable the EnableKerbAuthPersist registry value and restart the IIS service, IIS 6.0 no longer requires the client to reauthenticate for each HTTP request. Clients only have to reauthenticate if they make another HTTP request by using a different client TCP port. This scenario occurs when a new HTTP Keep-Alive session must be established. For more information about HTTP Keep-Alive sessions, visit the following Internet Engineering Task Force (IETF) Web site:

http://www.ietf.org/rfc/rfc2616.txt

For more information about software update terminology, 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

Additional query words: AuthPersistence AuthPersistSingleRequest

Keywords: kbbug kbfix kbqfe kbpubtypekc kbhotfixserver kbwinserv2003presp2fix kbwinserv2003sp2fix KB917557

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