OptiClass: An Optimized Classifier for Application Layer Protocols Using Bit Level Signatures

Network traffic classification has many applications, such as security monitoring, quality of service, traffic engineering, etc. For the aforementioned applications, Deep Packet Inspection (DPI) is a popularly used technique for traffic classification because it scrutinizes the payload and provides comprehensive information for accurate analysis of network traffic. However, DPI-based methods reduce network performance because they are computationally expensive and hinder end-user privacy as they analyze the payload. To overcome these challenges, bit-level signatures are significantly used to perform network traffic classification. However, most of these methods still need to improve performance as they perform one-by-one signature matching of unknown payloads with application signatures for classification. Moreover, these methods become stagnant with the increase in application signatures. Therefore, to fill this gap, we propose OptiClass, an optimized classifier for application protocols using bit-level signatures. OptiClass performs parallel application signature matching with unknown flows, which results in faster, more accurate, and more efficient network traffic classification. OptiClass achieves twofold performance gains compared to the state-of-the-art methods. First, OptiClass generates bit-level signatures of just 32 bits for all the applications. This keeps OptiClass swift and privacy-preserving. Second, OptiClass uses a novel data structure called BiTSPLITTER for signature matching for fast and accurate classification. We evaluated the performance of OptiClass on three datasets consisting of twenty application protocols. Experimental results report that OptiClass has an average recall, precision, and F1-score of 97.36%, 97.38%, and 97.37%, respectively, and an average classification speed of 9.08 times faster than five closely related state-of-the-art methods.