Installing Mosquitto
sudo add-apt-repository ppa:mosquitto-dev/mosquitto-ppa
sudo apt-get update
sudo apt-get install mosquitto mosquitto-clients
Installing Certbot for Let’s Encrypt Certificates
sudo add-apt-repository ppa:certbot/certbot
sudo apt-get update
sudo apt-get install certbot
Running Certbot
sudo ufw allow 80
sudo ufw allow 443
sudo certbot certonly --standalone
Enter your domain : mqtt.example.com
Setting up Certbot Automatic Renewals
sudo crontab -e
. . .
15 3 * * * certbot renew --noninteractive --post-hook "systemctl restart mosquitto"
Configuring MQTT Passwords
sudo mosquitto_passwd -c /etc/mosquitto/passwd sammy
sudo nano /etc/mosquitto/conf.d/default.conf
allow_anonymous false
password_file /etc/mosquitto/passwd
sudo systemctl restart mosquitto
Configuring MQTT SSL
sudo nano /etc/mosquitto/conf.d/default.conf
. . .
listener 1883 localhost
listener 8883
certfile /etc/letsencrypt/live/mqtt.example.com/cert.pem
cafile /etc/letsencrypt/live/mqtt.example.com/chain.pem
keyfile /etc/letsencrypt/live/mqtt.example.com/privkey.pem
sudo systemctl restart mosquitto
sudo ufw allow 8883
References
https://www.digitalocean.com/community/tutorials/how-to-install-and-secure-the-mosquitto-mqtt-messaging-broker-on-ubuntu-16-04