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windowmqttmosquitto

Which version of MQTT is Mosquitto broker hosting

Good day

I would like to host MQTT V1.3 or V1.3.1 with Mosquitto on Windows. The client I am connecting with only supports V1.3 and V1.3.1 while Mostquitto also supports V5.

How do I configure or how can I determine what version of MQTT has been hosted?

Thank you

Solution

  • The CONNECT packet is the first thing sent over the connection and includes a "Protocol Level" (v3.0 & 3.1 = 3 (cannot differentiate these two versions), v3.11 = 4, v5 = 5).

    The broker will process this and, if it does not support the requested level, respond with 'Unsupported Protocol Version' and disconnect.

    If the broker supports multiple versions of the protocol it will use the "Protocol Level" to determine which version of the protocol to use for the specific connection (it's quite possible to have v3.1.1 and v5 clients connected to Mosquitto at the same time).