MQTT Broker on Brainy Pi

MQTT is standard messaging protocol for IOT devices. It was designed as an extremely lightweight messaging transport. It is ideal for connecting remote devices with a small footprint. This protocol is used in a wide variety of industries.

Today, we are going to create a MQTT broker using BrainyPi.

A broker is a middle man which allows the MQTT clients to communicate. The broker receives the messages from clients, filters them by topic and then forwards them to the subscribers.

1. A brainyPI or RaspberryPI
2. keyboard
3. mouse

1. lets start by updating the operating system and then we will proceed with the installation.
2. After installation, run the systemctl command to check the status of the service.

sudo apt update
sudo apt upgrade
sudo apt install mosquitto mosquitto-clients
sudo systemctl status mosquitto

After running the first command, open up another session and run the following commands

mosquitto_sub -h localhost -t "mqtt/brainypi"

Open up another terminal session and run the commands below

mosquitto_pub -h localhost -t "mqtt/brainypi" -m "Hello world"

In the first window, you should see "Hello World" printed. Here, we first created a subscriber of the topic "mqtt/brainypi" and then we published a message for the same topic.

Now, that our setup is tested. We shall enable auto startup of the service so that in case of restart the service should restart automatically.

sudo systemctl enable mosquitto.service

4.1 By default, mqtt has stopped allowing remote connections.

4.2 We can change this behavior easily by editing the config file.

4.3 Run the following command to open the file.

sudo nano /etc/mosquitto/mosquitto.conf

4.4 Scroll to the bottom of the file, and add the following.

listener 1883
allow_anonymous true

4.5 This will enable "no authentication" method. This method is generally not recommended

4.6 Restart the service to apply the changes.

sudo systemcl restart mosquitto

5.1 We'll start by creating a password for a user.

sudo mosquitto_passwd -c /etc/mosquitto/passwd replace_this_with_your_name

5.2 Now, that we have created a password for the username. We need to tell MQTT to use it as default authentication method.

5.3 We can achieve the above by editing the configuration file

sudo nano /etc/mosquitto/mosquitto.conf

5.4 Add the following lines at the top of the file

per_listener_settings true

5.5 Add the following lines to the end of the file. These will tell Mosquitto where the password file lies.

allow_anonymous false
listener 1883
password_file /etc/mosquitto/passwd

We can add more users by running the command below

mosquitto_password passwd <username>

7.1 Last time we tested the configuration was without using username/password authentication.

mosquitto_sub -d -t brainypi -u <username> -P password@23

7.2 Sending the message

mosquitto_pub -d -t testTopic -m "Hello world!" -u dhruv -P password@23

8.1 MQTT can have multiple clients. To add them just run the commands below.

mosquitto_pub -h IP_ADDRESS_BRAINYPI -d -t testTopic -m "Hello world!" -u dhruv -P password@23

8.2 Remember to change the relevant details like ip address, topic name, username, and password.