Monitoring abnormal network traffic based on blind source separation approach

摘要

The randomness in network behaviors poses serious challenges for discovering abnormal patterns in network traffic flows. This paper presents a systematic approach for monitoring abnormal network traffic. The DFlow model is proposed to reduce the flow records and extract four features to capture the traffic patterns. The blind source separation method is applied to obtain the routine and abnormal behaviors from those features. A scale space filter is applied to filter the randomness in the traffic flows without affecting the behavior patterns. A threshold is selected based on a systematic criterion to evaluate the degree of abnormality. The contributions of different traffic features to the abnormal behavior detection are analyzed. It is found that the number of connection degree is the most important feature for traffic monitoring. A salient feature of this method is that it is effective for detecting the abnormal behaviors not associated with significant changes in traffic volumes. Another advantage of the new method is that no supervised learning process is needed. This is very important since high quality labeled samples are very difficult to acquire in actual networks especially the data traces associated with attacks. The experimental results based on the actual network data show that the method presented in the paper is effective for monitoring abnormal traffic flows in the gigabytes traffic environment and the accuracy is above 95%.