Installing MQTT Server

sudo apt-get install mosquitto

Modify the config file at /etc/mosquitto/mosquitto.conf

# Place your local configuration in /etc/mosquitto/conf.d/
#
# A full description of the configuration file is at
# /usr/share/doc/mosquitto/examples/mosquitto.conf.example
pid_file /var/run/mosquitto.pid
persistence true
persistence_location /var/lib/mosquitto/
log_dest file /var/log/mosquitto/mosquitto.log
#include_dir /etc/mosquitto/conf.d
allow_anonymous false
password_file /etc/mosquitto/pwfile
listener 51883

sudo mosquitto_passwd -c /etc/mosquitto/pwfile <username>