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Automatic Proxy Discovery in Internet Explorer with DHCP requires specific permissions

Article ID: 312864 - View products that this article applies to.

This article was previously published under Q312864

SYMPTOMS

You can configure Internet Explorer to use the Automatic Proxy Discovery functionality over Dynamic Host Configuration Protocol (DHCP). This option can direct Web clients to ISA Server's Web proxy service through Web Proxy Autodetect (WPAD) process. In Microsoft Windows 2000, this feature works only for users who are member of the Administrators or Power Users group. In Microsoft Windows XP, the Network Configuration Operators group also has permission to issue DHCP queries.

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CAUSE

DHCP client calls are implemented over a RAW named pipe. For security reasons, specific permissions are set on the named pipe. In Windows 2000, an access control entry (ACE) is set on the pipe for the Administrators and Power Users groups. In Windows XP, an ACE is also set for the Network Configuration Operators group.

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RESOLUTION

Microsoft Windows 2000

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, submit a request to Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site:

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

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

Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

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
   --------------------------------------------------------------
   08-Jul-2003  01:27  5.0.2195.6770      89,360  Dhcpcsvc.dll

Microsoft Windows XP

Service pack information

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

322389

(http://support.microsoft.com/kb/322389/ )

How to obtain the latest Windows XP service pack

Hotfix information

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

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

   Date         Time   Version            Size    File name
   --------------------------------------------------------------
   29-Mar-2004  09:20  5.1.2600.1351     103,936  Dhcpcsvc.dll

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WORKAROUND

To work around this behavior, use one of the following methods:

Make sure that the appropriate user belongs to one of the groups that are listed in the "Symptoms" section of this article.
Use an automatic configuration script instead of Automatic Proxy Discovery.

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STATUS

This behavior is by design. This problem was corrected in Microsoft Windows XP Service Pack 2.

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MORE INFORMATION

For more information about how to configure Automatic Proxy Discovery, click the following article number to view the article in the Microsoft Knowledge Base:

252898

(http://support.microsoft.com/kb/252898/ )

How to enable Proxy Autodiscovery in Windows 2000

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