locksense-server

This repository sets up a cloud server for an Internet of Things (IoT) system that serves as an MQTT broker and data storage provider.

Setting Up

1. Clone this Git repository.
2. Install Docker and Docker Compose on the host machine.
3. Configure authentication credentials for the MQTT broker by adding a password file to mqtt-broker/passwd. This file can be created by installing and running the mosquitto_passwd utility, which will then prompt for a password.

   mosquitto_passwd -c mqtt-broker/passwd <username>

4. Find a domain registrar and point your selected domain at the server's IP address.
5. Generate SSL certificates for your domain, then copy the certificates to the mosquitto/certs subdirectory:

   mkdir /mosquitto/certs
   cp -r -L /etc/letsencrypt/live/<domain> /mosquitto/certs

   • Note that the files under /etc/letsencrypt/live/<domain> are symbolic links to those under /etc/letsencrypt/archive/<domain>, so the -L option is used to follow the links and copy the contents of the actual files.
6. Change the ownership and group of the mosquitto/certs subdirectory so that it belongs to user 1883:

   chown -R 1883:1883 /mosquitto/certs

   • This step is necessary because as of V2.0, Mosquitto loads TLS certificates as an unprivileged user instead of the root user. Since the eclipse-mosquitto Docker image runs Mosquitto as user 1883 (mosquitto), this user must be able to access the certificates.
7. Start the application by running docker-compose from the root project directory:

   docker-compose up --detach

Usage

To test the connection to the MQTT broker from any machine, run the following in separate terminals:

mosquitto_sub -h <domain> -p 8883 -u <username> -P <password> -t test 

mosquitto_pub -h <domain> -p 8883 -u <username> -P <password> -t test -m "Hello World!"

Note that connections must be carried out over TLS, so we use the domain name (instead of an IP address) and specify port 8883 (instead of the default 1883).

The MQTT broker can also receive connections via WebSockets over TLS (WSS). Example code using the MQTT.js client library is given below:

const client = mqtt.connect(`wss://${MQTT_HOST}:9001`, {
  username: MQTT_USERNAME,
  password: MQTT_PASSWORD,
});

const topics = ['test', 'helloworld'];
client.on('connect', () => {
  console.log('Connected');
  client.subscribe(topics, (err, granted) => {
    console.log(`Subscribed to topic(s) '${granted.map((grant) => grant.topic).join("', '")}'`);

    client.publish('test', 'This works!', {}, (err) => {
      if (err) {
        console.error('Failed to publish message', err);
      }
    });
  });
});

client.on('message', (topic, message, packet) => {
  console.log(`[${topic}] Received Message:`, message.toString(), packet);
});

References & Links

• Setting up a secure MQTT broker (without Docker)
• Obtaining an SSL certificate from Let's Encrypt