Introduction
Mosquitto is a lightweight open source message broker that complies with the MQTT (Message Queuing Telemetry Transport) protocol. It is commonly used for messaging between IoT (Internet of Things) devices. The following is a detailed introduction to Mosquitto:
Features
- Lightweight: Mosquitto is designed to be suitable for devices with limited resources and can run on small servers and single-board computers.
- Support multiple platforms: It can run on multiple operating systems such as Linux, Windows, and macOS.
- Multi-user: Supports multiple client connections and can handle a large number of concurrent sessions.
- Support QoS levels: Supports three quality of service (QoS) levels of MQTT, allowing users to choose the reliability of message delivery according to their needs.
- QoS 0: At most once delivery
- QoS 1: At least once delivery
- QoS 2: Only once delivery
- Persistence: Supports persisting messages to disk to facilitate restoring session status after restart.
Usage scenarios
- IoT applications: widely used in smart home, industrial automation, environmental monitoring and other fields, devices can efficiently transmit messages through low-bandwidth networks.
- Mobile applications: support low-power devices to reduce battery consumption and achieve real-time data transmission.
- Inter-node communication: In distributed systems, Mosquitto can be used for asynchronous communication between different nodes.
Components
- Broker: The core of Mosquitto is the message broker (Broker), which is responsible for receiving, filtering, storing and forwarding messages. All communications are carried out through the Broker.
- Client: The application or device connected to the Broker can be a publisher, a subscriber, or both.
Security
- Authentication and authorization: Supports user authentication through username and password, and can control access to topics.
- SSL/TLS encryption: Supports encrypted connections to protect the security of data transmission.
Installation and use
- Installation: Mosquitto can be installed through Docker, package management tools (such as apt, yum) or compiled source code.
- Configuration: You can easily customize its behavior through configuration files, such as connection parameters, authentication, etc.
- Command line tools: mosquitto_pub and mosquitto_sub command line tools are provided for quick publishing and subscription of messages.

Community and Support
Mosquitto has an active development community with rich documentation and support channels. Developers can find resources, solve problems or contribute code from GitHub or official documents.
In summary, Mosquitto is a powerful and flexible message broker, which is very suitable for IoT and distributed application scenarios that require efficient communication. Its lightweight and ease of use make it a popular choice for developers and enterprises.
Related environment
Use MQTTX software and an actual serial port server for connection and communication. The serial port server uses the single serial port server of ebyte company for connection.
Mosquitto deployed system: Debian 12
Use SSH remote server for installation, SSH opens root privileges or uses sudo privileges for deployment (it is not recommended to use root privileges directly in formal deployment scenarios).

Related addresses
Mosquitto official website: https://mosquitto.org
Debian official website: https://www.debian.org
MQTTX official website: https://mqttx.app
Serial port server: https://www.ebyte.com/product/2124.html
For the use of serial port server, please refer to:
http://cloud.video.taobao.com/play/u/null/p/1/e/6/t/1/462554329255.mp4

Installation and deployment of Mosquitto
First, install the Mosquitto tool on the server or device. You can find the installation method on the Mosquitto official website. Here we demonstrate a simple installation on a Debian 12 system. The installation is relatively simple, and you can refer to the official guide for installation.
Most open source systems have added Mosquitto to the source, and you can directly use apt-get install mosquitto to install it.