title: Send message to everyone connected to LAN
body: <p>I want to send a message to everyone(broadcast) in my subnet(LAN) so as to prevent them using Internet due to repair work that's going to happen. How do i do that ? I can't use "wall" because no one is logged on some server.<br>
  I want to send a packet that opens a new Tab in web browser and displays message that stop using Internet during a certain duration.   </p>