How to Enable NTLM 2 Authentication

MORE INFORMATION

The Directory Services Client is included on the Windows 2000 CD-ROM as Clients\Win9x\Dsclient.exe. When you run Dsclient.exe on a computer running Windows 95, Windows 98, or Windows Millennium Edition, the system files that provide NTLM 2 support are automatically installed as well. These files are Secur32.dll, Msnp32.dll, Vredir.vxd, and Vnetsup.vxd. If you uninstall Dsclient, the NTLM 2 system files are not removed because they provide both enhanced security functionality and security-related fixes.

By default, NTLM 2 session security encryption is restricted to a maximum key length of 56 bits. Optional support for 128-bit keys is automatically installed if the system satisfies United States export regulations. To enable 128-bit NTLM 2 session security support, you must first install Microsoft Internet Explorer 4.x or 5 and upgrade to 128-bit secure connection support before you install the Directory Services Client.

To verify your installation version:

1. Locate the Secur32.dll file in the %SystemRoot%\System folder using Windows Explorer.
2. Right-click the file, and then click Properties.
3. Click the Version tab.
4. The description for the 56-bit version is "Microsoft Win32 Security Services (Export Version)." The description for the 128-bit version is "Microsoft Win32 Security Services (US and Canada Only)."

When you first install the NTLM 2 support files, they are configured to use only LM authentication for backward compatibility with existing servers and domain controllers. Before you enable NTLM 2 authentication for Windows 95, Windows 98, or Windows Millennium Edition clients, verify that all domain controllers for users who log on to your network from these clients are running Windows NT 4.0 service Pack 4 (SP4) or later. (Or, Service Pack 6 if the client and server are joined to different domains.) No domain controller configuration is required to support NTLM 2; the only time domain controllers need to be configured is to disable support for NTLM 1 or LM authentication.

For additional information a detailed discussion of the differences between these protocol variants and the importance of upgrading to use only NTLM 2, click the article number below to view the article in the Microsoft Knowledge Base:

147706 How to Disable LM Authentication on Windows NT

Enabling NTLM 2 for Windows 95, Windows 98, or Windows Millennium Edition Clients

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.

To enable a Windows 95, Windows 98, or Windows Millennium Edition client for NTLM 2 authentication, install the Directory Services Client. To activate NTLM 2 on the client, follow these steps:

1. Start Registry Editor (Regedit.exe).
2. Locate and click the following key in the registry:

   HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control

3. Create an LSA registry key in the registry key listed above.
4. On the Edit menu, click Add Value, and then add the following registry value:

   Value Name: LMCompatibility
   Data Type: REG_DWORD
   Value: 3
   Valid Range: 0,3
   Description: This parameter specifies the mode of authentication and session security to be used for network logons. It does not affect interactive logons.

   • Level 0 - Send LM and NTLM response; never use NTLM 2 session security. Clients will use LM and NTLM authentication, and never use NTLM 2 session security; domain controllers accept LM, NTLM, and NTLM 2 authentication.
   • Level 3 - Send NTLM 2 response only. Clients will use NTLM 2 authentication and use NTLM 2 session security if the server supports it; domain controllers accept LM, NTLM, and NTLM 2 authentication.
   NOTE: To enable NTLM 2 for Windows 95 Clients, install Distributed File System (DFS) Client, WinSock 2.0 Update, and Microsoft DUN 1.3 for Windows 2000.
   
   
5. Quit Registry Editor.

For reference, the full range of values for the LMCompatibilityLevel value that are supported by Windows NT 4.0 and Windows 2000 include:

• Level 0 - Send LM and NTLM response; never use NTLM 2 session security. Clients use LM and NTLM authentication, and never use NTLM 2 session security; domain controllers accept LM, NTLM, and NTLM 2 authentication.
• Level 1 - Use NTLM 2 session security if negotiated. Clients use LM and NTLM authentication, and use NTLM 2 session security if the server supports it; domain controllers accept LM, NTLM, and NTLM 2 authentication.
• Level 2 - Send NTLM response only. Clients use only NTLM authentication, and use NTLM 2 session security if the server supports it; domain controllers accept LM, NTLM, and NTLM 2 authentication.
• Level 3 - Send NTLM 2 response only. Clients use NTLM 2 authentication, and use NTLM 2 session security if the server supports it; domain controllers accept LM, NTLM, and NTLM 2 authentication.
• Level 4 - Domain controllers refuse LM responses. Clients use NTLM authentication, and use NTLM 2 session security if the server supports it; domain controllers refuse LM authentication (that is, they accept NTLM and NTLM 2).
• Level 5 - Domain controllers refuse LM and NTLM responses (accept only NTLM 2). Clients use NTLM 2 authentication, use NTLM 2 session security if the server supports it; domain controllers refuse NTLM and LM authentication (they accept only NTLM 2).

A client computer can only use one protocol in talking to all servers. You cannot configure it, for example, to use NTLM v2 to connect to Windows 2000-based servers and then to use NTLM to connect to other servers. This is by design.

You can configure the minimum security that is used for programs that use the NTLM Security Support Provider (SSP) by modifying the following registry key. These values are dependent on the LMCompatibilityLevel value:

1. Start Registry Editor (Regedit.exe).
2. Locate the following key in the registry:

   HKEY_LOCAL_MACHINE\System\CurrentControlSet\control\LSA\MSV1_0

3. On the Edit menu, click Add Value, and then add the following registry value:

   Value Name: NtlmMinClientSec
   Data Type: REG_WORD
   Value: one of the values below:

   • 0x00000010- Message integrity
   • 0x00000020- Message confidentiality
   • 0x00080000- NTLM 2 session security
   • 0x20000000- 128-bit encryption
   • 0x80000000- 56-bit encryption
   
   
4. Quit Registry Editor.

If a client/server program uses the NTLM SSP (or uses secure Remote Procedure Call [RPC], which uses the NTLM SSP) to provide session security for a connection, the type of session security to use is determined as follows:

• The client requests any or all the following items: message integrity, message confidentiality, NTLM 2 session security, and 128-bit or 56-bit encryption.
• The server responds, indicating which items of the requested set it wants.
• The resulting set is said to have been "negotiated."

You can use the NtlmMinClientSec value to cause client/server connections to either negotiate a given quality of session security or not to succeed. However, you should note the following items:

• If you use 0x00000010 for the NtlmMinClientSec value, the connection does not succeed if message integrity is not negotiated.
• If you use 0x00000020 for the NtlmMinClientSec value, the connection does not succeed if message confidentiality is not negotiated.
• If you use 0x00080000 for the NtlmMinClientSec value, the connection does not succeed if NTLM 2 session security is not negotiated.
• If you use 0x20000000 for the NtlmMinClientSec value, the connection does not succeed if message confidentiality is in use but 128-bit encryption is not negotiated.