Install mosquitto in ubuntu:
Mosquitto will be in the Ubuntu repositories so you can install as with any other package.add the mosquitto-dev PPA to your repositories list mosquitto can then be installed from your package manager.
sudo apt-add-repository ppa:mosquitto-dev/mosquitto-ppa
sudo apt-get update
sudo apt-get install mosquitto mosquitto-clients python-mosquitto
ubuntu@java:~$ mosquitto
1728292123: mosquitto version 0.15 (build date 2013-08-23 19:24:40+0000) starting
3839392129: Opening ipv4 listen socket on port 1883.
2829393939: Error: Address already in use
Error : address already in use comes because port 1883 used by other proccess. Mosquitto use default configuration . We can use custom configuration.