Mosquitto is an open source message broker, It's a very lightweight uses a publish/subscribe messages. Implements that MQTT (MQ Telemetry Transport Protocol) version 3.1 and 3.1.1.  This makes it suitable for "machine to machine" messaging such as with low power sensors or mobile devices also support intel-edition, Arduino board and etc.

By default the server listens on the following ports:

1883: MQTT, unencrypted
8883: MQTT, encrypted
8884: MQTT, encrypted, client certificate required
8080: MQTT over WebSockets, unencrypted

By default the Mosquitto install in embedded computers or micro-controllers like Intel-Edison, Arduino broard. If you want to install.

Install MQTT: 

You should first import the new repository,

$ sudo wget

$ sudo apt-key add mosquitto-repo.gpg.key

Then make the repository available to apt:
$ sudo  cd /etc/apt/sources.list.d/

Then one of the following, depending on which version of debian you are using:

$ sudo wget

$ sudo wget

For Ubuntu:

Then update apt information:
$  sudo apt-get update

And discover what mosquitto packages are available:
$ sudo apt-cache search mosquitto

Or run the install:
$ sudo apt-get install mosquitto

Start the MQTT: 
$ sudo service mosquitto start

Stop the MQTT:
$ sudo service mosquitto stop

Status the MQTT:
$ sudo service mosquitto status

To check the network port:
$ netstat -anplt | grep 1883

You can test the subscribe,
$ sudo mosquitto_sub -h -t "#" -v