title: HTTP/1.1 426 Upgrade Required
body: <p>When trying to connect to localhost (with Terminal), I got this answer:</p>
  
  <blockquote>
    <p>HTTP/1.1 426 Upgrade Required <br>
    Server: WebSocket++/0.3.0-alpha4</p>
  </blockquote>
  
  <p>How can I respond to that to Upgrade?</p>