ThingWorx WebSocket-based Edge MicroServer (WS EMS) and Lua Script Resource (LSR) > Additional Configuration of WS EMS > Configuring Edge Settings for Tunneling > Required Setting for the Tunneling Subsystem
  
Required Setting for the Tunneling Subsystem
When attempting to configure tunneling, you must check the configuration for the Tunneling Subsystem of the ThingWorx instance. There is a field where you can specify the host/IP of the end point for the tunnel, called Public host name used for tunnel. The following figure shows the configuration page for the Tunneling Subsystem, with this field highlighted:
Configuring the Tunnel Subsystem
Why do you need to configure this address? Suppose that you start up your ThingWorx instance in Amazon EC2. The default IP address for the Tunneling Subsystem when the ThingWorx instance is running in EC2 might be 10.128.0.x. Unless you change that address, the Tunneling Subsystem will tell the clients to attempt to connect to that address for the tunnel websocket. Since that IP address is a local network address, the tunnel will not work. Therefore, you must populate that configuration field with the external host/IP address that tunnels will use for connections.