An Efficient Pattern Matching Algorithm for Intrusion Detection Systems

Intrusion detection systems are treated as vital elements of protective measures to computer systems and networks from abuse. The drastic increase in network speed and detection workloads necessitates the need for highly efficient Network Intrusion Detection Systems(NIDS). Since most NIDSs need to check for a large number of known attack patterns in every packet, pattern matching becomes the most significant part of signature-based NIDSs in terms of processing and memory resources. To support segmentation of network traffic and to detect fragmented attacks, we propose a method which performs both 'partial' and 'full' pattern matching using the data structure CDAWG (Compact Direct Acyclic Word Graph). In the present work, we designed and implemented an efficient string matching algorithm using CDAWG structure. Experimental results show that this algorithm is 2.5 times faster than the currently used Aho-Corasick algorithm.