Connectivity to IPSec Clients May Be Lost When You Enable Packet Filters on Server (257949)

The information in this article applies to:

Microsoft Windows 2000 Server
Microsoft Windows 2000 Advanced Server
Microsoft Windows 2000 Professional

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

Modification Type:	Minor	Last Reviewed:	6/1/2006
Keywords:	kbQFE kbHotfixServer kbbug kbfix kbWin2000SP1Fix KB257949