Voice & messagingTCP 1883, 8883 Cleartext by default
Port 1883, 8883: MQTT
MQTT
Lightweight publish/subscribe messaging for IoT. 1883 is cleartext; 8883 is MQTT over TLS.
Secure alternative: MQTT over TLS (8883)
How attackers abuse it
- Anonymous brokers letting anyone read sensor data or publish commands.
- Wildcard subscriptions exposing every topic.
How to defend it
- Use 8883 with client authentication.
- Topic-level access control lists.
Exam tip
IoT protocols often trade security for low overhead - assume no authentication unless configured.