The secure_tunnel module implements a "Line Protocol". When this protocol is chosen by a Line, it sends data received via TLS out on the Line. It sends data received on the Line out via TLS when it receives <Enter> or fills its 80 character buffer.
As delivered in the SDK, the module listens for a TLS connection on all interfaces addressed to the LOCAL_PORT 10001. When the connection is established, it sends "Connected" to the Line. Subsequently it listens to the line for data to send out via TLS. The #define REMOTE_ADDRESS must be commented out to operate in this listening mode.
Be sure to add "secure_tunnel" TLS Credential in TLS Credential Management
Alternately, you can change the #define REMOTE_ADDRESS to either an IP address or a host name to operate in a connect mode. In this case you must also set the #define REMOTE_PORT. When the connection is established, it sends "Connected" to the Line.
Build it from project "secureTunnelDemo".