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ClearBlade IoT Core supports the MQTT protocol by running a managed broker that listens to the port mqtt.googleapis.com: 8883. Port 8883 is the standard TCP port reserved with IANA for secure MQTT connections. Connections to this port must use TLS transport, which is supported by open source clients like Eclipse Paho.
If port 8883 is blocked by your firewall, you can also use port 443: mqtt.googleapis.com: 443.
Note: The MQTT standard is defined for implementing a full publish/subscribe broker. However, the managed MQTT bridge run by ClearBlade IoT Core does not support all publish/subscribe operations, such as creating arbitrary topics that devices can use to send messages between them. (Filtering can be accomplished with downstream processes running on Cloud Pub/Sub.) ClearBlade IoT Core uses a predefined set of topics and specific topic formats.
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