When two client computers try to use the server message block (SMB) protocol to connect to the same server across a network address translation (NAT) device, the more recent client connection may reset the earlier client connection. If a client and a server that use the SMB protocol over a NAT device are copying files, that session may be reset when another client uses the SMB protocol over the same NAT device to the same server.

Note This problem does not occur when the server is running Microsoft Windows NT 4.0.

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When a new connection is established to a server, the server checks for previous connections from the same client IP address and deletes any previous connections. Because NAT acts as a proxy for the SMB protocol by using the same IP address from the two client connection requests, the earlier connection is terminated.

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Note The latest service pack is not requried to resolve this problem for Microsoft Windows Server 2003-based comptuers.

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: The English version of this fix 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
   ----------------------------------------------------------
   09-Aug-2001  17:35  5.0.2195.4110  1,685,696  Ntkrnlmp.exe
   09-Aug-2001  17:35  5.0.2195.4110  1,685,312  Ntkrnlpa.exe
   09-Aug-2001  17:36  5.0.2195.4110  1,705,984  Ntkrpamp.exe
   09-Aug-2001  17:34  5.0.2195.4110  1,663,424  Ntoskrnl.exe
   09-Aug-2001  17:34  5.0.2195.4110    237,104  Srv.sys
   09-Aug-2001  17:37  5.0.2195.3805     73,488  Srvsvc.dll
				

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Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section. This problem was first corrected in Windows 2000 Service Pack 3.

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This fix applies only to the SMB protocol traffic over TCP NetBIOS port 139. The connectivity problem that is mentioned in this article still occurs on client computers that are running Windows 2000 or later if you make the connection with direct hosting on port 445. By default, Windows 2000 uses this port.

You can establish no more than one direct hosting client connection across a NAT device. If you must have more than one simultaneous SMB protocol, disable either direct hosting on the Windows 2000 file server or on all clients behind the NAT device.

To disable direct hosting on the server:

1.	Start Registry Editor.
2.	Locate and then click the following registry key: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\NetBT\Parameters
3.	Add the following registry value: Value Name: SmbDeviceEnabled Type: REG_DWORD Value Data: 0 The default setting is 1 (enabled)

When you complete these steps, clients must use port 139 NetBIOS over TCP/IP to make a connection.

Note To permit multiple connections over the NAT device, Microsoft recommends that you use Web Distributed Authoring and Versioning (WebDAV). With this technology, you can perform standard file operations on a remote share. For additional information about how to install Windows 2000 and Windows 2000 hotfixes at the same time, click the following article number to view the article in the Microsoft Knowledge Base:

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