I found this code on the MSDN site, from a post thats about a year old.
It does seem to work. However, I'm confused in how to use the impersonated
user.
I'd like to use impersonatedUse r to run some SQL commands. Any idea how I
would do this?
Thanks
Vayse
'************** *************** *************** *************** **************
Imports System
Imports System.Runtime. InteropServices
Imports System.Security .Principal
Imports System.Security .Permissions
Public Class LoginForm
Protected Friend canceled As Boolean = False
Friend Impersonating As Boolean = False
Private Sub btnOK_Click(ByV al sender As System.Object, ByVal e As
System.EventArg s) Handles btnOK.Click
Me.btnOK.Enable d = False
Me.Cursor = Cursors.WaitCur sor
If Impersonate_Use r() Then
Me.txtInfo.Text = My.User.Name
MsgBox("Success !")
End If
Me.btnOK.Enable d = True
Me.Cursor = Cursors.Default
End Sub
Private Function Impersonate_Use r() As Boolean
Dim tbtnOKenHandle As New IntPtr(0)
Dim dupeTbtnOKenHan dle As New IntPtr(0)
Try
Dim userName, domainName As String
domainName = txtDomain.Text
userName = txtUserName.Tex t
Const LOGON32_PROVIDE R_DEFAULT As Integer = 0
'This parameter causes LogonUser to create a primary tbtnOKen.
Const LOGON32_LOGON_I NTERACTIVE As Integer = 2
tbtnOKenHandle = IntPtr.Zero
' Call LogonUser to obtain a handle to an access tbtnOKen.
Dim returnValue As Boolean = LogonUser(userN ame, domainName,
txtPassword.Tex t, LOGON32_LOGON_I NTERACTIVE, LOGON32_PROVIDE R_DEFAULT,
tbtnOKenHandle)
'Set the flag on the form to see if they are impersonating
Impersonating = returnValue
If returnValue = False Then
Dim ret As Integer = Marshal.GetLast Win32Error()
Throw New System.Componen tModel.Win32Exc eption(ret)
Impersonate_Use r = False
Else
' Check the identity.
Debug.Print("Be fore impersonation: " +
WindowsIdentity .GetCurrent().N ame)
' Use the tbtnOKen handle returned by LogonUser.
Dim newId As New WindowsIdentity (tbtnOKenHandle )
Dim impersonatedUse r As WindowsImperson ationContext =
newId.Impersona te()
' Check the identity.
Debug.Print("Af ter impersonation: " +
WindowsIdentity .GetCurrent().N ame)
' Free the tbtnOKens.
If Not System.IntPtr.o p_Equality(tbtn OKenHandle,
IntPtr.Zero) Then
CloseHandle(tbt nOKenHandle)
End If
Impersonate_Use r = True
End If
Catch ex As Exception
MessageBox.Show (("Exception occurred. " + ex.Message),
Application.Pro ductName, MessageBoxButto ns.OK, MessageBoxIcon. Error)
End Try
End Function
Private Sub Cancel_Click(By Val sender As System.Object, ByVal e As
System.EventArg s) Handles btnCancel.Click
canceled = True
Me.Close()
End Sub
Private Declare Auto Function LogonUser Lib "advapi32.d ll" (ByVal
lpszUsername As [String], _
ByVal lpszDomain As [String], ByVal lpszPassword As [String], _
ByVal dwLogonType As Integer, ByVal dwLogonProvider As Integer, _
ByRef phTbtnOKen As IntPtr) As Boolean
<DllImport("ker nel32.dll")_
Public Shared Function FormatMessage(B yVal dwFlags As Integer, ByRef
lpSource As IntPtr, _
ByVal dwMessageId As Integer, ByVal dwLanguageId As Integer, ByRef
lpBuffer As [String], _
ByVal nSize As Integer, ByRef Arguments As IntPtr) As Integer
End Function
Public Declare Auto Function CloseHandle Lib "kernel32.d ll" (ByVal
handle As IntPtr) As Boolean
Public Declare Auto Function DuplicateTbtnOK en Lib "advapi32.d ll" (ByVal
ExistingTbtnOKe nHandle As IntPtr, _
ByVal SECURITY_IMPERS ONATION_LEVEL As Integer, _
ByRef DuplicateTbtnOK enHandle As IntPtr) As Boolean
Private Sub LoginForm_Load( ByVal sender As System.Object, ByVal e As
System.EventArg s) Handles MyBase.Load
Me.txtInfo.Text = My.User.Name
End Sub
End Class
