MQTT

MQTT is two different things in MeshSat and it is worth keeping them apart.

As a transport

The bridge can publish to and subscribe from any MQTT broker you point it at, so messages flow between MeshSat and anything else that speaks MQTT: home automation, an existing telemetry pipeline, another site.

As the link to the Hub

The bridge's connection to the Hub is also MQTT, over a WebSocket, with a client certificate as the identity. That is a separate thing from the transport above and is configured separately. See Connect a bridge.

Topics

Topics follow meshsat/{device}/... for the default account and meshsat/{account}/{device}/... for every other one. The suffix says what the message is: mo/raw, mo/decoded, position, telemetry, sos, status/health and so on.

A bridge is told its own prefix when it is provisioned rather than working it out, so a bridge belonging to one account cannot publish into another's namespace by guessing a topic.