Overview
MQTT over TCP is the standard, unencrypted transport protocol for MQTT connections. HiveMQ CE listens on port 1883 by default for TCP connections.
Configuration
Basic TCP Listener
<hivemq>
<listeners>
<tcp-listener>
<port>1883</port>
<bind-address>0.0.0.0</bind-address>
</tcp-listener>
</listeners>
</hivemq>
Configuration Options
| Option | Description | Default |
|---|
port | TCP port number | 1883 |
bind-address | Network interface to bind | 0.0.0.0 (all interfaces) |
name | Listener name for identification | auto-generated |
Multiple Listeners
<hivemq>
<listeners>
<tcp-listener>
<port>1883</port>
<bind-address>0.0.0.0</bind-address>
<name>default-listener</name>
</tcp-listener>
<tcp-listener>
<port>1884</port>
<bind-address>192.168.1.100</bind-address>
<name>internal-listener</name>
</tcp-listener>
</listeners>
</hivemq>
Connecting Clients
Python (paho-mqtt)
import paho.mqtt.client as mqtt
def on_connect(client, userdata, flags, rc):
print(f"Connected with result code {rc}")
client = mqtt.Client()
client.on_connect = on_connect
client.connect("localhost", 1883, 60)
client.loop_forever()
Java (HiveMQ MQTT Client)
import com.hivemq.client.mqtt.mqtt5.Mqtt5BlockingClient;
import com.hivemq.client.mqtt.mqtt5.Mqtt5Client;
public class MqttExample {
public static void main(String[] args) {
Mqtt5BlockingClient client = Mqtt5Client.builder()
.identifier("my-client")
.serverHost("localhost")
.serverPort(1883)
.buildBlocking();
client.connect();
System.out.println("Connected!");
}
}
JavaScript (MQTT.js)
const mqtt = require('mqtt');
const client = mqtt.connect('mqtt://localhost:1883');
client.on('connect', () => {
console.log('Connected!');
});
Mosquitto CLI
# Subscribe
mosquitto_sub -h localhost -p 1883 -t "test/topic"
# Publish
mosquitto_pub -h localhost -p 1883 -t "test/topic" -m "Hello"
Security Considerations
TCP transport is unencrypted. Credentials and message payloads are transmitted in plain text. Use TLS for production deployments.
When to Use TCP
- ✅ Development and testing
- ✅ Trusted internal networks
- ✅ Already encrypted at network layer (VPN)
- ❌ Public networks
- ❌ Sensitive data
- ❌ Compliance requirements
Firewall Configuration
Linux (iptables)
sudo iptables -A INPUT -p tcp --dport 1883 -j ACCEPT
sudo iptables-save
Linux (firewalld)
sudo firewall-cmd --permanent --add-port=1883/tcp
sudo firewall-cmd --reload
Docker
docker run -d --name hivemq-ce -p 1883:1883 hivemq/hivemq-ce
Next Steps
TLS Transport
Secure your MQTT connections with TLS/SSL
Connecting Clients
More client connection examples
Configuration Guide
Advanced listener configuration
WebSocket Transport
MQTT over WebSocket
