Installing MQTT

In order to install MQTT on mu linux server machine I took the following steps:

sudo apt update
sudo apt install mosquitto-clients
sudo apt install mosquitto
sudo systemctl status mosquitto to check if mosquitto has been installed
sudo systemctl enable mosquitto to get mosuitto started on system start
sudo mosquitto_passwd -c /etc/mosquitto/passwd david to set a userid and password for authentication to mosquitto (NOT the password to the linux account)
sudo nano /etc/mosquitto/conf.d/default.conf and set the contents to:
```
allow_anonymous false
password_file /etc/mosquitto/passwd
```
sudo systemctl restart mosquitto