title: Can websocket access devices behind firewall/router once connection is setup?
body: <p>I'm wondering whether my server can access the devices behind firewall using web sockets, once the connection is established by that device (as the server is accessible by that devices)?</p>
  
  <p>I've read <a href="https://stackoverflow.com/questions/36484813/how-to-make-request-from-server-to-devices-behind-router">this answer</a>, that has mentioned this same scenario, but from the answer it's not clear that whether the server can access the devices behind router or not. </p>
  
  <p>If this is possible, I want to use socket.io to first initiate the connection by client to server and then making clients accessible from server to further communication.</p>
  
  <p>I would have tried this by my self, but I don't have such setup available rightnow. Thanks!</p>