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Q166730: With Unencrypted Password SP3 Fails to Connect to SMB Server

Article: Q166730
Product(s): Microsoft Windows NT
Version(s): 4.0,4.0 SP3,4.0 SP4
Operating System(s): 
Keyword(s): kbnetworkkbbuglist kbfixlist
Last Modified: 08-AUG-2001

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The information in this article applies to:

- Microsoft Windows NT Workstation versions 4.0, 4.0 SP3, 4.0 SP4 
- Microsoft Windows NT Server versions 4.0, 4.0 SP3 
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SYMPTOMS
========

After upgrading your Windows NT 4.0 computer to Service Pack 3 (SP3), you are
unable to connect to certain non-Microsoft Server Message Block (SMB) servers
and you may receive the following error message:

  System error 1240 has occurred.

  The account is not authorized to login from this station.

CAUSE
=====

Some non-Microsoft SMB servers only support unencrypted (plain text) password
exchanges during authentication.

The SMB client redirector in Windows NT 4.0 Service Pack 3 and later handles
unencrypted passwords differently than previous versions of Windows NT.
Beginning with Windows NT 4.0 Service Pack 3, the SMB redirector does not send
an unencrypted password during authentication to an SMB server unless you add a
specific registry entry.

In previous versions, the client would automatically negotiate downward to
unencrypted (plain text) authentication if requested from the server.

RESOLUTION
==========

Check with the vendor of the SMB server product to see if there is a way to
support encrypted password authentication, or if there is a newer version of the
product that adds this support.

Alternatively, to enable unencrypted (plain text) passwords for the SMB client on
Windows NT 4.0 Service Pack 3 and newer systems, modify the registry in the
following way:

WARNING: Enabling this will allow unencrypted (plain text) passwords to be sent
across the network when authenticating to an SMB server that requests this
option. This can lessen the overall security of an environment and should only
be done after careful consideration of the consequences of plain text passwords
in your specific environment.

WARNING: Using the registry editor incorrectly can cause serious, system-wide
problems that may require you to reinstall Windows NT. Microsoft cannot
guarantee that any problems resulting from the use of the registry editor can be
solved. Use this tool at your own risk.

1. Run Registry Editor (Regedt32.exe).

2. From the HKEY_LOCAL_MACHINE subtree, go to the following key:

  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Rdr\Parameters

3. On the Edit menu, click Add Value.

4. Add the following:

     Value Name: EnablePlainTextPassword
     Data Type: REG_DWORD
     Data: 1

5. Click OK and then quit Registry Editor.

6. Shut down and restart Windows NT.

To enable unencrypted (plain text) passwords in an automated setup, modify the
registry in the following way:

Add the following line to the Product.Add.Reg section of the Update.inf file:

  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Rdr\Parameters,
  "EnablePlainTextPassword", 0x10001, 1


Additional query words: 4.00 VAX log in login 2510

======================================================================
Keywords          : kbnetwork kbbuglist kbfixlist
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNTW400 kbWinNTW400search kbWinNT400search kbWinNTW400sp4 kbWinNTW400sp3 kbWinNTSsearch kbWinNTS400sp3 kbWinNTS400search kbWinNTS400
Version           : :4.0,4.0 SP3,4.0 SP4
Issue type        : kbinfo

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