Eclipse Mosquitto* is an open source (EPL/EDL licensed) message broker that implements the MQTT protocol versions 3.1 and 3.1.1. MQTT provides a lightweight method of carrying out messaging using a publish/subscribe model. This makes it suitable for "Internet of Things" messaging such as with low power sensors or mobile devices such as phones, embedded computers or microcontrollers like the Arduino.
$ git clone git@github.com:eclipse/mosquitto.git
$ cd mosquitto
$ cmake .
$ make
$ sudo make install