Install Mosquitto MQTT Broker on Raspberry Pi

This tutorial shows how to install the Mosquitto Broker for MQTT communication on a Raspberry Pi board.

You can also run Mosquitto MQTT broker in the cloud. Running the MQTT Mosquitto Broker in the cloud allows you to connect several ESP32/ESP8266 boards and other IoT devices from anywhere using different networks as long as they have an Internet connection.

What is an MQTT Broker?

MQTT stands for Message Queuing Telemetry Transport. MQTT is a simple messaging protocol, designed for constrained devices with low bandwidth. So, it’s the perfect solution to exchange data between multiple IoT devices.

MQTT communication works as a publish and subscribe system. Devices publish messages on a specific topic. All devices that are subscribed to that topic receive the message.

The MQTT broker is responsible for receiving all messages, filtering the messages, deciding who is interested in them, and then publishing the message to all subscribed clients.

There are several brokers you can use. In home automation projects, we use the Mosquitto Broker installed on a Raspberry Pi.

You can also install the Mosquitto broker on your PC (which is not as convenient as using a Raspberry Pi board, because you have to keep your computer running all the time to keep the MQTT connection between your devices alive).

For a more detailed explanation of MQTT communication, check out this article: What is MQTT and How It Works

Prerequisites

Before continuing with this tutorial

• You should be familiar with the Raspberry Pi board – read Getting Started with Raspberry Pi;
• You should have the Raspberry Pi OS installed in your Raspberry Pi – Install Raspberry Pi OS, Set Up Wi-Fi, Enable and Connect with SSH;
• You also need the following hardware:
  • Raspberry Pi board 
  • MicroSD Card – 16GB Class10
  • Raspberry Pi Power Supply (5V 2.5A)

Installing Mosquitto Broker on Raspberry Pi OS

After having your Raspberry Pi board prepared with Raspberry Pi OS, you can continue with this tutorial. 

Let’s install the Mosquitto Broker.

1) Open a new Raspberry Pi terminal window. If you’re running your Raspberry Pi headless, check this tutorial to learn how to establish an SSH connection between your computer and the Raspberry Pi.

2) Run the following command to upgrade and update your system:

sudo apt update && sudo apt upgrade

3) Press Y and Enter. It will take some time to update and upgrade (in my case, it took approximately 10 minutes).

4) To install the Mosquitto Broker enter these next commands:

sudo apt install -y mosquitto mosquitto-clients

5) To make Mosquitto auto start when the Raspberry Pi boots, you need to run the following command (this means that the Mosquitto broker will automatically start when the Raspberry Pi starts):

sudo systemctl enable mosquitto.service

6) Now, test the installation by running the following command:

mosquitto -v

This returns the Mosquitto version that is currently running in your Raspberry Pi. It will be 2.0.11 or above.

It will prompt the following message: “Starting in local only mode. Connections will only be possible from clients running on this machine. Create a configuration file which defines a listener to allow remote access.”

This means that by default, you can’t communicate with the Mosquitto broker from another device (other than your Raspberry Pi). This is applicable for Mosquitto version 2. More information about this topic on the Mosquitto documentation.

“In Mosquitto 2.0 and up, you must choose your authentication options explicitly before clients can connect. In earlier versions, the default is to allow clients to connect without authentication.“

Enable Remote Access/ Authentication

To enable remote access so that we can communicate with other IoT devices, we need to edit/create a configuration file.

In this tutorial, we’ll cover:

• No Authentication
• Authentication with user and password

Choose the section that is more suitable for your scenario. We also recommend taking a look at the documentation for more details.

Mosquitto Broker Enable Remote Access (No Authentication)

1) Run the following command to open the mosquitto.conf file.

sudo nano /etc/mosquitto/mosquitto.conf

2) Move to the end of the file using the arrow keys and paste the following two lines:

listener 1883

allow_anonymous true

 
3) Then, press CTRL-X to exit and save the file. Press Y and Enter.
 
4) Restart Mosquitto for the changes to take effect.

sudo systemctl restart mosquitto

Mosquitto Broker Enable Remote Access (Authentication: user and password)

You can add a user/password authentication to your MQTT broker.

1) Run the following command, but replace YOUR_USERNAME with the username you want to use:

sudo mosquitto_passwd -c /etc/mosquitto/passwd YOUR_USERNAME

I’ll be using the MQTT user sara, so I run the command as follows:

sudo mosquitto_passwd -c /etc/mosquitto/passwd sara

When you run the preceding command with the desired username, you’ll be asked to enter a password. No characters will be displayed while you enter the password. Enter the password and memorize the user/pass combination, you’ll need it later in your projects to make a connection with the broker.

This previous command creates a password file called passwd on the /etc/mosquitto directory.

Now, we need to edit the mosquitto configuration file so that it only allows authentication with the username and password we’ve defined.

2) Run the following command to edit the configuration file:

sudo nano /etc/mosquitto/mosquitto.conf

3) Add the following line at the top of the file (make sure it is at the top of the file, otherwise it won’t work):

per_listener_settings true

4) Add the following three lines to allow connection for authenticated users and tell Mosquitto where the username/password file is located.

allow_anonymous false
listener 1883
password_file /etc/mosquitto/passwd

Your configuration file will look as follows (the new lines are in bold):

# 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

per_listener_settings true

pid_file /run/mosquitto/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 
listener 1883  
password_file /etc/mosquitto/passwd

5) Press CTRL-X, then Y, and finally press Enter to exit and save the changes.

6) Restart Mosquitto for the changes to take effect.

sudo systemctl restart mosquitto

To check if Mosquitto is actually running, you can run the following command:

sudo systemctl status mosquitto

Now, you have authentication with username and password enabled. Remember that everytime you want to communicate with the broker, you’ll need to provide the username and password.

Add More Users/Change Password

To add more users to an existing password file, or to change the password for an existing user, leave out the -c argument:

mosquitto_passwd <password file> <username>

For example, if I want to change the password for the sara user and taking into account that the password file we created was called passwd, the command will be as follows:

sudo mosquitto_passwd /etc/mosquitto/passwd sara

Raspberry Pi IP Address

To use Mosquitto broker later in your projects, you’ll need to know the Raspberry Pi IP address. To retrieve your Raspberry Pi IP address, type the next command in your Pi Terminal window:

hostname -I

In our case, the Raspberry Pi IP address is 192.168.1.144. Save your Raspberry Pi IP address because you’ll need it in future projects.

Testing Mosquitto Broker and MQTT Client

After installing the Mosquitto broker, you should test your installation. You can follow the next tutorial:

• Testing Mosquitto Broker and Client on Raspbbery Pi

Wrapping Up

An MQTT broker is essential if you want to use the MQTT protocol in IoT projects. The MQTT broker receives all MQTT messages and forwards them to all subscribed clients. In this tutorial, you’ve learned how to install the Mosquitto broker on a Raspberry Pi.

Thanks for reading.