MQTT

What is MQTT?

MQTT stands for MQ Telemetry Transport. It is a publish/subscribe, extremely simple and lightweight messaging protocol, designed for constrained devices and low-bandwidth, high-latency or unreliable networks. The design principles are to minimise network bandwidth and device resource requirements whilst also attempting to ensure reliability and some degree of assurance of delivery. These principles also turn out to make the protocol ideal of the emerging “machine-to-machine” (M2M) or “Internet of Things” world of connected devices, and for mobile applications where bandwidth and battery power are at a premium.

Commands

Subscribing to all broker statuses:

mosquitto_sub -h TARGET_IP -t '$SYS/#' -v

To publish on the sub_topic:

mosquitto_pub -h TARGET_IP -t '<sub_topic>' -m 'Test'

The sub_topic can be found by using the first command. It might be encoded in base64.

To publish on the pub_topic:

mosquitto_pub -h TARGET_IP -t '<pub_topic>' -m 'Test'

The pub_topic, is found in the same way the sub_topic is found. This publisher shows the result of the command you sent while using the mosquitto_pub command.

You might have to publish a message encoded in base64, so be careful!

Example:

Format: base64({"id": " ", "cmd": " ", "arg": " "})

To listen to the pub_topic:

mosquitto_sub -h TARGET_IP -t '<pub_topic>' -v