Microsoft KB Archive/103826

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User Authentication Fails on LAN Manager Client

Article ID: 103826

Article Last Modified on 11/1/2006


  • Microsoft Windows 3.1 Standard Edition
  • Microsoft Windows NT Advanced Server 3.1

This article was previously published under Q103826


Windows NT does not properly store passwords with extended characters in the Microsoft LAN Manager-compatible password entry in the Security Accounts Manager (SAM) database. This may cause your Microsoft LAN Manager, Remote Access Service (RAS), or Macintosh clients to fail authentication if their passwords contain extended characters.


Each user account has two passwords, both a LAN Manager and a Windows NT-compatible password. Each password is doubly encrypted and stored in the SAM database. The two passwords enable Windows NT to validate your account for both Windows NT and LAN Manager clients.

LAN Manager passwords are not case-sensitive. Before they are encrypted, they are converted to all uppercase letters. Windows NT has no way of making an extended character uppercase in a consistant manner due to the differences in foreign languages and code pages. Because of this, Windows NT stores only makes non-extended characters uppercase; it leaves extended characters alone.

Because Windows NT handles extended characters in this manner, your password may not match up with the one stored on a LAN Manager client.

NOTE: This problem only occurs when a password is originally created from Windows NT User Manager or during initial logon. If the password is created by using the LAN Manager client NET PASSWORD command, it is stored properly in the Windows NT SAM database. Also, if the password is created with PORTUAS, it should be all right.


Microsoft has confirmed this to be a problem in Windows NT and Windows NT Advanced Server version 3.1, and Windows NT Workstation and Server versions 3.1.We are researching this problem and will post new information here in the Microsoft Knowledge Base as it becomes available.


For more information on Windows NT authentication or why RAS must convert the character case of passwords, query on the following words in the Microsoft Knowledge Base:

ras\sfm and password and authentication

For more information on other password authentication problems, see the Knowledge Base article entitled, "RAS\SFM use LAN Manager Password Authentication."

For more information on Windows NT Authentication, see the Knowledge Base Article entitled, "INF: User Authentication with Windows NT."

Additional query words: prodnt

Keywords: kbnetwork KB103826