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Q310934: Event 51 Logged During Failed Host-Initiated Password Change

Article: Q310934
Product(s): Microsoft SNA Server
Version(s): 
Operating System(s): 
Keyword(s): kbDSupport kbhis2000 kbhis2000bug
Last Modified: 11-JUN-2002

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The information in this article applies to:

- Microsoft Host Integration Server 2000 
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IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

  Q256986 Description of the Microsoft Windows Registry

SYMPTOMS
========

Host-initiated password changes are not replicated to the Windows NT or Windows
2000 accounts database when you are using the password synchronization feature
that is included with Host Integration Server (HIS) 2000.

An event 51 will be logged in the Application Event Log on the Windows NT or
Windows 2000 primary domain controller (PDC) where the SNA WinNT Account
Synchronization (SnaPMP) service is running when this problem occurs:

  Event ID: 51
  Source: SNA Host Security
  Description: The Windows NT Account Synchronization service could not validate
  an RPC request.

This problem only occurs when the following registry entry is set to 1, which is
the default value:

  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SnaPMP\Parameters\ValidateHostRequest

CAUSE
=====

The SNA Host Account Cache service fails to return the user's previous host
password to the SNA WinNT Account Synchronization service so that it can be
validated prior to changing the user's Windows NT or Windows 2000 password. The
password change request cannot be completed if the previous host password is not
available for validation when ValidateHostRequest=1. This results in the event
51 and the failure to change the user's Windows NT/Windows 2000 password.

WORKAROUND
==========

WARNING: If you use Registry Editor incorrectly, you may cause serious problems
that may require you to reinstall your operating system. Microsoft cannot
guarantee that you can solve problems that result from using Registry Editor
incorrectly. Use Registry Editor at your own risk.

If there is no requirement to have a user's previous host password validated by
the HIS 2000 host security components before the user's Windows NT/Windows 2000
password is changed, this functionality can be disabled. The validation of a
user's previous host password can be disabled by modifying the registry as
follows:

1. Start Registry Editor (Regedt32.exe).

2. Locate the ValidateHostRequest value under the following key in the registry:

  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SnaPMP\Parameters\ValidateHostRequest

3. From the Edit menu, click DWORD, type "0" (without the quotation marks), and
  then click OK.

4. Quit Registry Editor.

STATUS
======

Microsoft has confirmed this to be a problem in Microsoft Host Integration
Server 2000.


MORE INFORMATION
================

The ValidateHostRequest parameter was added in SNA Server 3.0 SP1. For
additional information, click the article number below to view the article in
the Microsoft Knowledge Base:

  Q164652 Verify Old Passwords Before Updating SNA Host Account Database

The SnaPMP service can be installed on any Windows NT or Windows 2000 domain
controller (DC), but it only actually runs on the PDC. If the SnaPMP service is
installed on other DCs as well, the ValidateHostRequest parameter should be
configured with the same value in case one of the other DCs is ever promoted or
assumes the PDC role.

The following Knowledge Base article describes another host-initiated password
change problem that occurs with HIS 2000:

  Q310517 Event 1301 Logged During Host-Initiated Password Change

Additional query words:

======================================================================
Keywords          : kbDSupport kbhis2000 kbhis2000bug 
Technology        : kbAudDeveloper kbHostIntegServ2000
Version           : :
Issue type        : kbbug
Solution Type     : kbnofix

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