Windows-based Authentication

If User.IsInRole("Administrators") Then
    DisplayPrivilegedContent()
End If

The WindowsPrincipal class determines roles by NT group membership. Applications that want to determine their own roles can do so by handling the WindowsAuthentication_OnAuthenticate event in their Global.asax file and attaching their own class that implements System.Security.Principal.IPrincipal to the request, as shown in the following example:

' Create a class that implements IPrincipal
Public Class MyPrincipal : Inherits IPrincipal
  ' Implement application-defined role mappings
End Class

' In a Global.asax file
Public Sub WindowsAuthentication_OnAuthenticate(Source As Object, e As WindowsAuthenticationEventArgs)
  ' Attach a new application-defined class that implements IPrincipal to
  ' the request.
  ' Note that since IIS has already performed authentication, the provided
  ' identity is used.
  e.User = New MyPrincipal(e.Identity)
End Sub

The following sample shows how to access the name of an authenticated user, which is available as User.Identity.Name. Programmers familiar with ASP should note that this value is also still available as the AUTH_USER server variable:

VB Windows Authentication [Run Sample] | [View Source]