Abstract
The exponential growth of networked systems has intensified cybersecurity threats, making real-time anomaly detection in network traffic a critical research imperative. This thesis proposes a novel framework for anomaly detection in network traffic leveraging advanced machine learning techniques including deep auto encoders, graph neural networks (GNNs), and transformer-based temporal modeling. Unlike traditional signature-based intrusion detection systems, the proposed approach employs unsupervised learning to establish baseline network behavior patterns from unlabeled traffic data, enabling the identification of zero-day attacks, DDoS floods, and subtle lateral movement activities. The methodology integrates three synergistic components: (1) a multi-scale convolutional auto encoder that captures spatial-temporal traffic patterns across packet, flow, and session levels; (2) a Graph Attention Network (GAT) that models dynamic communication topologies between network entities; and (3) a transformer architecture with positional encoding to capture long-range temporal dependencies in traffic sequences. Feature engineering incorporates 32 network flow metrics (IPFIX-compliant) including packet inter-arrival times, byte distributions, protocol entropy, and flow duration statistics. The reconstruction error from the auto encoder, combined with graph anomaly scores and temporal deviation metrics, feeds into a one-class SVM for final anomaly classification. Evaluation on benchmark datasets (CICIDS2017, UNSW-NB15, and MAWI real-world traces) demonstrates superior performance with 98.2% AUC, 4.1% false positive rate, and 12ms inference latency on 10Gbps traffic. The framework achieves 27% higher F1-score compared to Isolation Forest, 19% improvement over LSTM-based methods, and 3x faster inference than GAN-based approaches. Real-time deployment results on enterprise edge routers confirm scalability to 40Gbps throughput with sub-50ms detection latency. This research advances the state-of-the-art by addressing key limitations of existing methods: lack of multi-scale temporal modeling, inadequate handling of encrypted traffic, and poor generalization across attack families. The proposed solution offers a deployable, hardware-agnostic anomaly detection system suitable for 5G core networks, IoT edge gateways, and cloud security stacks, providing robust defense against evolving cyber threats through continuous adaptation and minimal human supervision.