Install MQTT Broker on Raspberry Pi

Download GPG Key and add it

curl -O http://repo.mosquitto.org/debian/mosquitto-repo.gpg.key
sudo apt-key add mosquitto-repo.gpg.key
rm mosquitto-repo.gpg.key

Download mosquitto repo list

cd /etc/apt/sources.list.d/
sudo wget http://repo.mosquitto.org/debian/mosquitto-wheezy.list

Update all the packages

sudo apt-get update

List mosquitto packages available

sudo apt-cache search mosquitto

Or just install:

sudo apt-get install mosquitto