Network intrusion detection using machine learning approaches: Addressing data imbalance

Cybersecurity has become a significant issue. Machine learning algorithms are known to help identify cyberattacks such as network intrusion. However, common network intrusion datasets are negatively affected by class imbalance: the normal traffic behaviour constitutes most of the dataset, whereas intrusion traffic behaviour forms a significantly smaller portion. A comparative evaluation of the performance is conducted of several classical machine learning algorithms, as well as deep learning algorithms, on the well-known National Security Lab Knowledge Discovery and Data Mining dataset for intrusion detection. More specifically, two variants of a fully connected neural network, one with an autoencoder and one without, have been implemented to compare their performance against seven classical machine learning algorithms. A voting classifier is also proposed to combine the decisions of these nine machine learning algorithms. All of the models are tested in combination with three different resampling techniques: oversampling, undersampling, and hybrid sampling. The details of the experiments conducted and an analysis of their results are then discussed.