Modeling and evaluation of a new IoT security system for mitigating DoS attacks to the MQTT broker

In recent years, technology use has assumed an important role in the support of human activities. Intellectual work has become the main preferred human activity, while structured activities are going to become ever more automatized for increasing their efficiency. For this reason, we assist to the diffusion of ever more innovative devices able to face new emergent problems. These devices can interact with the environment and each other autonomously, taking decisions even without human control. This is the Internet of Things (IoT) phenomenon, favored by low cost, high mobility, high interaction and low power devices. This spread of devices has become uncontrolled, but security in this context continues to increase slowly. The purpose of this work is to model and evaluate a new IoT security system. The context is based on a generic IoT system in the presence of lightweight actuator and sensor nodes exchanging messages through Message Queue Telemetry Transport (MQTT) protocol. This work aims to increase the security of this protocol at application level, particularly mitigating Denial of Service (DoS) attacks. The system is based on the use of a host Intrusion Detection System (IDS) which applies a threshold based packet discarding policy to the different topics defined through MQTT.