A Feature Selection Approach for Network Intrusion Classification: The Bi-Layer Behavioral-Based

Feature selection is a preprocessing step to machine learning, leads to increase the classification accuracy and reduce its complexity. Feature selection methods are classified into two main categories: filter and wrapper. Filter methods evaluate features without involving any learning algorithm, while wrapper methods depend on a learning algorithm for feature evaluation. Variety hybrid Filter and wrapper methods have been proposed in the literature. However, hybrid filter and wrapper approaches suffer from the problem of determining the cut-off point of the ranked features. This leads to decrease the classification accuracy by eliminating important features. In this paper the authors proposed a Hybrid Bi-Layer behavioral-based feature selection approach, which combines filter and wrapper feature selection methods. The proposed approach solves the cut-off point problem for the ranked features. It consists of two layers, at the first layer Information gain is used to rank the features and select a new set of features depending on a global maxima classification accuracy. Then, at the second layer a new subset of features is selected from within the first layer redacted data set by searching for a group of local maximum classification accuracy. To evaluate the proposed approach it is applied on NSL-KDD dataset, where the number of features is reduced from 41 to 34 features at the first layer. Then reduced from 34 to 20 features at the second layer, which leads to improve the classification accuracy to 99.2%.