How to Install and Secure the Mosquitto MQTT Messaging Broker

[MQTT](http://mqtt.org/) is a machine-to-machine messaging protocol, designed to provide lightweight publish/subscribe communication to “Internet of Things” devices. [Mosquitto](https://mosquitto.org/) is a popular MQTT server (or *broker*, in MQTT parlance) that has great community support and is easy to install and configure. In this tutorial, we’ll install Mosquitto, retrieve SSL certificates from Let’s Encrypt, and set up our broker to use SSL to secure our password-protected MQTT communications.