Microsoft KB Archive/257949

= Connectivity to IPSec Clients May Be Lost When You Enable Packet Filters on Server =

Article ID: 257949

Article Last Modified on 2/21/2007

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APPLIES TO


 * Microsoft Windows 2000 Server
 * Microsoft Windows 2000 Advanced Server
 * Microsoft Windows 2000 Professional Edition

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This article was previously published under Q257949



SYMPTOMS
After you enable packet filters on the server, connectivity to IP Security (IPSec) clients may be lost.



CAUSE
This behavior occurs because the Tcpip.sys file does not hand the original packets from Network Driver Interface Specification (NDIS) to IPSec, which causes IPSec to recalculate the hash for a packet that is already unencrypted.



RESOLUTION
To resolve this problem, obtain the latest service pack for Windows 2000. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

260910 How to Obtain the Latest Windows 2000 Service Pack



WORKAROUND
To work around this problem, disable packet filters on the server side host.



STATUS
Microsoft has confirmed that this is a problem in Microsoft Windows 2000.

This problem was first corrected in Windows 2000 Service Pack 1.



MORE INFORMATION
Because the fault is internal to the operating system subsystem, a trace or packet capture does not reveal this problem. Traffic seems to flow normally to the end point, and then disappears into the server without acknowledgement.

For additional information about how to install Windows 2000 and Windows 2000 hotfixes at the same time, click the article number below to view the article in the Microsoft Knowledge Base:

249149 Installing Microsoft Windows 2000 and Windows 2000 Hotfixes

Additional query words: offload traffic fail fails os endpoint

Keywords: kbqfe kbhotfixserver kbbug kbfix kbwin2000sp1fix KB257949

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