Runtime : Ensure that a random PSK secret compatible with stunnel is generated if -s commandline switch is used. Stunnel service is restarted after generation, using spawn_subprocess. TODO : give stunnel restart command as a commandline parameter.

<?xml version='1.0' encoding='utf-8'?>
<ModbusServerNode xmlns:xsd="http://www.w3.org/2001/XMLSchema" Local_Port_Number="1502" Local_IP_Address="127.0.0.1"/>