Abstract:
Internet of Things (IoT) networks are ubiquitous across industries, homes, and critical
infrastructure due to their automation capabilities. However, IoT devices remain highly
vulnerable to Distributed Denial-of-Service (DDoS) attacks owing to their limited
computational power and inherent heterogeneity. Also, IoT systems often favor usability
over security. While deep learning has shown promise for detecting such attacks, existing
approaches have largely been validated on conventional network datasets using
centralized architectures that create single points of failure. Furthermore, the centralized
approaches raise privacy concerns by requiring raw data transmission to the cloud and
lack preprocessing tailored to IoT-specific protocols such as MQTT. This study aimed to
develop a distributed deep learning framework for DDoS detection in IoT environments.
The specific objectives were to design and implement a distributed detection framework
based on deep learning, and to evaluate and compare its performance against a centralized
paradigm using accuracy, precision, recall, and F1-score. A quantitative experimental
research design using the DoS/DDoS-MQTT-IoT dataset was employed. The proposed
framework integrated three components: a CNN-BiLSTM ensemble model, a three-tier
edge-fog-cloud architecture incorporating federated learning where edge devices
performed preprocessing and fog nodes conducted local training while raw data remained
on premises, and preprocessing adapted to MQTT's publish-subscribe semantics. Model
hyperparameters were held constant across both experimental conditions, and ten-fold
cross-validation was applied. Statistical significance was assessed using a paired t-test
with an alpha level of 0.05. The distributed detection framework achieved 99.68%
accuracy, 99.02% precision, 99.28% recall, and 99.10% F1-score. The distributed
framework demonstrated a 64% lower error rate than the centralized approach (1.35%
versus 3.76%). This improvement was statistically significant as confirmed by a paired t
test over ten-fold cross-validation (p < 0.001). The distributed framework also
outperformed traditional machine learning methods and standalone deep learning models
including CNN alone, BiLSTM alone, and RNN alone. Overall, the distributed approach
exhibits superior accuracy and adaptability compared to centralized detection. It also
provides privacy benefits through federated learning. Future work should validate the
framework on additional IoT protocols and datasets and explore model compression
techniques to further reduce computational requirements on resource-constrained edge
devices.