Connecting objects in the IoT such as cars, homes, and machines exposes lots of sensitive data. Therefore, IoT security is a key concern and an important challenge for any IoT application. Since some of the data generated is not meant for the public, it should be protected by the five pillars of IT security: Confidentiality, Integrity, Availability, Authenticity, Non-Repudiation. This presentation explores how the five pillars of IT security can be implemented to secure IoT applications using MQTT.