title: Using Windows Authentication inside my own login form
body: <p>I have WPF application that has a login form. I would like to make all existing windows users that belong to some specific group able to log into my application.</p>
  
  <p>So what I need is a way after the user have given his username and password to see if this is a user, belonging to the wanted group, and that the password is correct. The feedback I can use to decide if the user gets logged in or not.</p>