VPN clients can no longer access internal resources after you install Windows Server 2003 Service Pack 1 on a computer that is running ISA Server 2000 (897651)


The information in this article applies to:

  • Microsoft Windows Server 2003 SP1, when used with:
    • Microsoft Windows Server 2003, Enterprise Edition
    • Microsoft Windows Server 2003, Standard Edition
  • Microsoft Windows Server 2003, Enterprise Edition for Itanium-based Systems
  • Microsoft Windows Server 2003, Standard x64 Edition
  • Microsoft Windows Server 2003, Enterprise x64 Edition
  • 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

After you install Microsoft Windows Server 2003 Service Pack 1 (SP1) on a computer that is running Microsoft Internet Security and Acceleration (ISA) Server 2000, remote virtual private network (VPN) clients who connect to internal resources through ISA Server 2000 can no longer access those resources.

When you perform additional troubleshooting on the client computer, you notice all the following symptoms:
  • The client computer successfully connects to the computer that is running ISA Server 2000 by using the VPN connection.
  • The user is successfully authenticated, and the client computer is successfully registered on the network.
  • The client computer has an IP address assigned to the wide area network (WAN) miniport virtual network adapter.
  • When you use the Ping.exe command to verify network connectivity, you notice that the client computer can only "ping" itself successfully. In this situation, the VPN client computer cannot connect to other computers.

CAUSE

This problem occurs because of a change in Windows Server 2003 SP1. Windows Server 2003 SP1 enables the BootTimeSecurity registry entry. Therefore, after you install Windows Server 2003 SP1, the Windows Server 2003 Ipnat.sys driver drops VPN packets that it receives.

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 Windows Server 2003 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

No prerequisites are required to install this hotfix.

Restart requirement

You must 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.

Windows Server 2003, x86-based versions
   Date         Time   Version        Size     File name
   -----------------------------------------------------
   04-May-2005  02:22  5.2.3790.2437  102,912  Ipnat.sys


Windows Server 2003, x64-based versions
   Date         Time   Version        Size     File name
   -----------------------------------------------------
   04-May-2005  16:42  5.2.3790.2437  155,648  Ipnat.sys


Windows Server 2003, Itanium-based versions
   Date         Time   Version        Size     File name
   -----------------------------------------------------
   04-May-2005  16:42  5.2.3790.2437  349,184  Ipnat.sys

Hotfix installation 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.

After you install this hotfix, you must set the value for the following registry subkey:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\IpNat\Parameters

You must set this value as follows:

Value name: DisableBootTimeSecurity
Value type: REG_DWORD
Value data: 1

WORKAROUND

To work around this problem, remove Windows Server 2003 SP1.

STATUS

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

MORE INFORMATION

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 kbHotfixServer kbFirewall kbBug kbfix kbpubtypekc KB897651 kbAudITPRO
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