Mosquitto is a lightweight open source message broker that Implements MQTT versions 3.1 and 3.1.1.
It is written in C by Roger Light, and is available as a free download for Windows and Linux and is an Eclipse project.
The main website is here.
Installing The Broker
To use it you will first need to install it.
- How to Install The Mosquitto MQTT Broker on Linux (Ubuntu)
- How to Install The Mosquitto MQTT Broker on Windows
Starting and Stopping The Broker
Depending on the install it will probably be started automatically on system startup.
On Windows you can stop the service if it is running by using the control panel>admin>services.
You can also the net command:
net stop mosquitto
On Linux use:
sudo service mosquitto stop
Starting from command line is the best option when testing and to do that use:
Windows
mosquitto -v #start in verbose mode
Linux
sudo mosquitto -v #start in verbose mode
To see other start options use:
mosquitto -h
By default the broker will start listening on port 1883. You can change that by editing the configuration file-mosquitto.conf See Quick Guide to The Mosquitto.conf File With Examples
Alternatively you can use a command line switch to specify the port e.g.
mosquitto -p 1884
You can run Multiple brokers on the same machine by starting them on different ports See this video- on running multiple brokers.
Mosquitto Client Scripts
The mosquitto install includes the client scripts.
There is a simple subscriber client
mosquitto_sub
and a publisher client
mosquitto_pub
They are useful for some quick tests. See Using The Mosquitto_pub and Mosquitto_sub Client Tools- Examples
Other Tutorials
- Understanding and Configuring Logging – Mosquitto Broker Configuration
- Restrictions
- Mosquitto Username and Password Authentication -Configuration and Testing
- Mosquitto SSL Configuration -MQTT TLS Security
- Mosquitto MQTT Bridge-Usage and Configuration
- Configure Mosquitto Bridge With SSL Encryption- Examples
- Configuring and Testing Mosquitto MQTT Topic
Port is above 1024, no need to use sudo on Linux
Hi Steve.
Thanks for your publications. I recently had a question for you and your answer was very helpful. I have another one. I installed Mosquitto broker in Raspberry Pi. After a lot of problems I finally managed to have it running. I have one application (IoTView by an industrial software manufacturer) who is accessing the broker, suscribing and publishing. At the same time I have another application (Web Studio) from the same manufacturer running on a PC, acting as a server who records the information on a database. On the tests, only one of them (IoTView) could run with no problems, while the other one stop working. I have been doing modifications for several months thinking the problem was on the application. Yesterday the manufacturer let me know the problem was on the Broker running on Raspberry Pi. It could not attend two connections at the same time…. Since you know this subject more than anyone I know, I would like your opinion. Is that so? It makes no sense for me that the broker on Raspberry Pi can attend only one connection at the same time. Is there not a parameter whom I can modify to alter this? The manufacturer reccomendation was to switch and install a broker on the Server. The PC running windows.
Hi
I run Mosquitto on Pi with multiple connections. Are you using different client names for the clients? The client ID needs to be unique.
Also start the broker with the -v option so you can see the connections and responses.
rgds
steve