Software
Mosquitto MQTT broker and clients
Pass small messages between sensors and automations.
What it does
A publisher sends a payload to a topic. The broker forwards it to subscribers. Authentication controls who connects; topic permissions control what they can do.
Connections and compatibility
Use a local-only listener for first experiments. A network listener needs explicit authentication, access rules, and appropriate transport protection.
Choosing one
The free broker and command-line clients can run on an existing computer. Pin the configuration to the major version you install.
Common mistakes
Retained state can be stale, and retained actuator commands can run again after reconnect. Do not expose an unauthenticated broker.
Use it in a tutorial
- Security for your smart home and IoT network — Give a small connected project clear permissions, visible failure states, and a repeatable security check before relying on it.
- MQTT security — Run a loopback-only Mosquitto practice broker, give a sensor and reader different permissions, and test the denied cases.