impersonation in vb.net

13 Feb 2006 4:24 PM

Nadeem Ahmed

Hi,
    I am trying to impersonate a local user on windows 2000 server in vb.net
application using following piece of code

Public Class ADVAPI32
    ' LogonUser call
    Public Declare Auto Function LogonUser Lib "advapi32.dll" _
    (ByVal lpszUserName As String, ByVal lpszDomain As String, _
     ByVal lpszPassword As String, ByVal dwLogonType As Integer, _
     ByVal dwLogonProvider As Integer, ByRef phToken As IntPtr) As Integer
    Public Enum Logon
        Batch = 1
        Interactive = 2
        NetworkCleartext = 8
    End Enum
    Public Enum Provider
        [Default] = 0
        WindowsNT35 = 1
        WindowsNT40 = 2
        Windows2000 = 3
    End Enum
    Public Declare Auto Function CloseHandle Lib "kernel32.dll" _
    (ByVal hObject As IntPtr) As Integer
End Class

when I call following method, providing only user name and password, it
always returns 0.

ADVAPI32.LogonUser(username, domain, password, ADVAPI32.Logon.Interactive,
ADVAPI32.Provider.Default, hUser)

Can you please explain why its returing zero?

Thanks.

13 Feb 2006 4:53 PM

Joe Kaplan (MVP - ADSI)

As the documentation for LogonUser states, it requires the TCB privilege
(act as part of the operating system) under Windows 2000. Only the SYSTEM
account has this by default. XP and 2003 do not have this restriction.

Note that it is a good idea to use Microsoft's sample implementation from
the MSDN docs for WindowsImpersonationContext instead of roling your own
wrapper here.

Joe K.

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"Nadeem Ahmed" <Nadeem Ah***@discussions.microsoft.com> wrote in message
news:52C3119F-BB03-4DC2-8EA1-1058E0F16081@microsoft.com...
> Hi,
>    I am trying to impersonate a local user on windows 2000 server in
> vb.net
> application using following piece of code
>
> Public Class ADVAPI32
>    ' LogonUser call
>    Public Declare Auto Function LogonUser Lib "advapi32.dll" _
>    (ByVal lpszUserName As String, ByVal lpszDomain As String, _
>     ByVal lpszPassword As String, ByVal dwLogonType As Integer, _
>     ByVal dwLogonProvider As Integer, ByRef phToken As IntPtr) As Integer
>    Public Enum Logon
>        Batch = 1
>        Interactive = 2
>        NetworkCleartext = 8
>    End Enum
>    Public Enum Provider
>        [Default] = 0
>        WindowsNT35 = 1
>        WindowsNT40 = 2
>        Windows2000 = 3
>    End Enum
>    Public Declare Auto Function CloseHandle Lib "kernel32.dll" _
>    (ByVal hObject As IntPtr) As Integer
> End Class
>
> when I call following method, providing only user name and password, it
> always returns 0.
>
> ADVAPI32.LogonUser(username, domain, password, ADVAPI32.Logon.Interactive,
> ADVAPI32.Provider.Default, hUser)
>
> Can you please explain why its returing zero?
>
> Thanks.