# mqtt(): Send messages from a local network to an MQTT broker

From version 3.33, you can use the `mqtt()` destination to publish messages to MQTT brokers.

The mqtt() destination builds on the [MQTT protocol](<https://www.hivemq.com/mqtt-protocol/>), and uses its “[client](<https://www.hivemq.com/blog/seven-best-mqtt-client-tools/>)” and “[broker](<https://www.hivemq.com/hivemq/mqtt-broker/>)” entities.

Note The rest of this chapter and its sections build on your familiarity with the MQTT protocol, the concept of client and broker entities, and how these entities function within an MQTT system. 

## Declaration:
```
       destination d_mqtt { 
          mqtt(
            topic("<topic-name>"), 
            address("tcp://localhost:<port-number>"),   
            fallback_topic("<fallback-topic-name>")
          ); 
        }
    
```

## Example: Using the mqtt() destination in your configuration

The following example illustrates a `mqtt()` destination configured to fetch messages from the `localhost:4444` address, and send them to the broker running on `localhost:4445`, using the `mqtt test/test` topic.
```
 
       @version: 3.32
        @include "scl.conf"
        
          source s_net { 
            network(port(4444)
          ); 
        };
        
          destination d_mqtt { 
            mqtt(topic("test/test"), address("tcp://localhost:4445"), fallback_topic("test/test")
          ); 
        };
                        
        log { 
          source(s_net); 
          destination( d_mqtt); 
        };
    
```

* * *

[Prerequisites to using the mqtt() destination](../../docs/axosyslog-core/chapter-destinations/destination-mqtt-intro/destination-mqtt-prer/index.md)

[Limitations to using the mqtt() destination](../../docs/axosyslog-core/chapter-destinations/destination-mqtt-intro/destination-mqtt-lim/index.md)

[Options of the mqtt() destination](../../docs/axosyslog-core/chapter-destinations/destination-mqtt-intro/destination-mqtt-options/index.md)

[Possible error messages you may encounter while using the mqtt() destination](../../docs/axosyslog-core/chapter-destinations/destination-mqtt-intro/destination-mqtt-error/index.md)

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