Testing the MQTT TLS configuration with GUI tools

Now, we will use the MQTT.fx GUI utility to generate another MQTT client that uses an encrypted connection to publish messages to the same topic: sensors/octocopter01/altitude. We have to make changes to the connection options to enable TLS and specify the certificate authority certificate file. Follow these steps:

1. Launch MQTT.fx, select local mosquitto in the drop-down located at the upper-left corner, and click on the configuration icon at the right-hand side of this drop-down and at the left-hand side of the Connect button. MQTT.fx will display the Edit Connection Profiles dialog box with different options for the connection profile named local mosquitto.
2. Go to the Broker Address textbox and enter the IPv4 or IPv6 address that we specified as the value in the Common Namefield when we generated the server.csr file, that is, the server certificate signing request. If you used a host name as the value in the Common Name field instead of an...