RPC UseWinsockForIP Is Only Applicable to UDP and IPX

• Microsoft Windows NT Server versions 4.0 SP2, 4.0 SP3
• Microsoft Windows NT Workstation versions 4.0 SP2, 4.0 SP3
• Microsoft Windows NT Server, Enterprise Edition version 4.0
• Microsoft Windows NT Server version 4.0, Terminal Server Edition

SYMPTOMS

Winsock Proxy lets a Windows Sockets application, running on a private network client, behave as if it were directly connected to a remote Internet server application when, in fact, the Microsoft Proxy Server is the host for this connection. This means that all application-level communications are channeled through a single secured computer -- the gateway computer running Microsoft Proxy Server.

Ordinarily, for datagram packet transfers, the RPC transport DLL bypasses the sendto( ) and recvfrom( ) functions provided in Wsock32.dll, and communicates directly with the underlying device driver. This improves the speed of packet transfers but makes Winsock Proxy features unavailable to the application.

Effective with Windows NT 4.0 with Service Pack 2, the RPC transport checks the registry to see whether to use the function calls provided in Wsock32.dll or to talk directly with the device driver.

NOTE: To use RPC with Winsock Proxy, you must add the following information to the registry:

WARNING: Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.

For information about how to edit the registry, view the "Changing Keys And Values" Help topic in Registry Editor (Regedit.exe) or the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe. Note that you should back up the registry before you edit it.

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Rpc\UseWinsockForIP

REG_DWORD "1"

CAUSE

RPC on Windows NT uses optimization for connection oriented traffic. This optimization includes calling the TDI transport. As a result, RPC bypasses the Winsock proxy.

RESOLUTION

To resolve this problem, obtain the latest service pack for Windows NT 4.0 or Windows NT Server 4.0, Terminal Server Edition. For additional information, please see the following article in the Microsoft Knowledge Base:

Q152734 How to Obtain the Latest Windows NT 4.0 Service Pack

1. Apply Windows NT 4.0 Service Pack 4.
   
   NOTE: The third-party application must also be a Winsock 2.1 LSP (layered service provider).



2. Copy the %SystemRoot%\System32\Rpcltscm.dll file to another name (for example, Rpclts13.dll).



3. For the protocol that is being implemented by the LSP (for example, TCP/IP), replace the reference to Rpcltscm.dll in the registry with the above name. For example,
   
   change:
   
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Rpc\ServerProtocols
   \ncacn_ip_tcp=rpcltscm.dll
   
   to:
   
   HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Rpc\ServerProtocols
   \ncacn_ip_tcp=rpclts13.dll



4. Shut down and restart your computer.

STATUS

Microsoft has confirmed this to be a problem in Windows NT 4.0 and Windows NT Server 4.0, Terminal Server Edition. This problem was first corrected in Windows NT 4.0 Service Pack 4.0 and Windows NT Server 4.0, Terminal Server Edition Service Pack 4.

Keywords : NT4SP4Fix NT4SP4Fea
Version : WinNT:4.0
Platform : winnt
Issue type : kbinfo