How to disable the IP Spoof Detection feature in ISA Server 2004, ISA Server 2006, Microsoft Forefront Threat Management Gateway Medium Business Edition or Windows Essential Business Server 2008

Applies to: Microsoft Forefront Threat Management Gateway Medium Business Edition

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:
322756 How to back up and restore the registry in Windows

INTRODUCTION


By default, the IP Spoof Detection feature is enabled in Microsoft Internet Security and Acceleration (ISA) Server 2004, in Microsoft Internet Security and Acceleration (ISA) Server 2006, in Microsoft Forefront Threat Management Gateway Medium Business Edition, and in Windows Essential Business Server 2008. Although there is no way to disable this feature in the ISA Microsoft Management Console (MMC) snap-in, you can disable this feature in the Windows registry.

More Information


To have us enable the IP Spoof Detection feature is for you, go to the "Fix it for me" section. If you’d rather enable the IP Spoof Detection feature yourself, go to the "Let me fix it myself" section.

Fix it for me

To enable the IP Spoof Detection feature automatically, click the Fix this problemlink. Then, click
Run in the File Downloaddialog box and follow the steps in this wizard.





Note this wizard may be in English only; however, the automatic fix also works for other language versions of Windows.

NoteIf you are not on the computer that has the problem, you can save the automatic fix to a flash drive or to a CD so that you can run it on the computer that has the problem.

Let me fix it myself

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.

To disable the IP Spoof Detection feature in the Windows registry yourself, follow these steps:
  1. Click Start, click Run, type regedit, and then click OK.
  2. Locate and then click the following registry subkey:
    HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services/FwEng/Parameters
    If the Parameters subkey is not displayed, follow these steps to create this subkey:
    1. Click theFwEng subkey.
    2. On the Edit menu, point to New, and then click Key.
    3. To name the key, type Parameters, and then press ENTER.
  3. Right-click Parameters, point to New, and then click DWORD Value.
  4. To name the value, type DisableSpoofDetection, and then press ENTER.
  5. Right-click DisableSpoofDetection, and then click Modify.

  6. In the Value data box, type 1, and then click OK.



    Warning This setting disables IP Spoof Detection. To enable IP Spoof Detection, set the DisableSpoofDetection value to 0. This is the default value.
  7. Exit Registry Editor, and then restart the ISA Server 2004/2006 Engine from the command line, with the command net stop fweng /y to stop the ISA Server Kernel Mode service and all depending services. After the engine stopped sucessfully start the Microsoft Firewall Service and the depended services with the command net start fwsrv.

References


For more information, click the following article numbers to view the articles in the Microsoft Knowledge Base:
284811 How to disable the IP spoofing detection feature in Internet Security and Acceleration Server 2000
832659 The IP Spoof Detection feature in ISA Server 2000 may drop legal packets on systems that have multiple external interfaces
833786 Steps that you can take to help identify and to help protect yourself from deceptive (spoofed) Web sites and malicious hyperlinks