title: Create WindowsIdentity using just a domain and username
body: <p>I am building a site that gets user information using the WindowsIdentity of the current user.  The main info I get from this is the ssid.</p>
  
  <p>I do this for the current users as follows</p>
  
  <pre><code>IntPtr logonToken = WindowsIdentity.GetCurrent().Token;
  WindowsIdentity windowsId = new WindowsIdentity(logonToken);
  string ssid = windowsId.User.ToString();
  </code></pre>
  
  <p>What I need to do now, and am failing at, is getting the ssid for any arbitrary username that exists on the domain.</p>
  
  <p>I tried WindowsIdentity(string), but that gave me a SecurityException</p>
  
  <blockquote>
    <p>The name provided is not a properly formed account name.</p>
  </blockquote>