In this article, we will delve into understanding Mosquitto MQTT broker log messages, specifically focusing on the NewConnection message. Mosquitto is an open-source MQTT (Message Queuing Telemetry Transport) broker, which is widely used for IoT (Internet of Things) projects. Understanding these log messages can help you troubleshoot and monitor your MQTT-based applications.
Mosquitto MQTT Broker Log Messages
Mosquitto generates log messages to help administrators and developers understand various events and issues related to the MQTT broker. These log messages can be found in the /var/log/mosquitto.log file by default. Analyzing these log messages can provide valuable insights into the system's health and performance.
NewConnection Message
The NewConnection message is generated when a new MQTT client connects to the broker. The log message includes the client's IP address, port number, and the connection protocol (MQTT or Websockets). Let's examine the provided log message:
2024-11-15T11:23:03: New connection from 172.17.0.2:41779 port 1883.
connection match: None
The log message indicates that a new connection was established from the IP address 172.17.0.2 on port 41779. The connection was made using the default MQTT port 1883. The connection match: field shows that there was no matching access control list (ACL) for this connection.
Parsing the Log Message
The log message consists of several fields separated by spaces. Here's a breakdown of the fields in the provided log message:
- Timestamp: The date and time when the event occurred.
- New connection: Indicates that a new connection has been established.
- From: The IP address of the connecting client.
- Port: The port number used by the client to connect.
- Protocol: The communication protocol used for the connection (MQTT or Websockets). In this case, it's MQTT.
- connection match: The result of the access control list (ACL) check. In this example, there was no matching ACL.
Understanding Access Control Lists (ACLs)
Access control lists (ACLs) are used to restrict access to the MQTT broker based on specific conditions. For example, you can restrict access to certain topics or limit the number of connections from a specific IP address. When a new connection is established, the Mosquitto broker checks the ACLs to determine if the connection should be allowed.
In this article, we explored the Mosquitto MQTT broker log messages, specifically focusing on the NewConnection message. We examined the log message fields and their meanings, including the IP address, port number, protocol, and access control list check result. Understanding these log messages can help you monitor and troubleshoot your MQTT-based applications.