Date Added: Apr 2011
The authors propose Dialog-based Payload Aggregation (DPA) that extracts relevant payload data from TCP/IP packet streams based on sequence numbers in the TCP header for improved intrusion detection performance. Typical network-based Intrusion Detection Systems (IDSs) like Snort, which use rules for matching payload data, show severe performance problems in high-speed networks. Their detailed analysis based on live network traffic reveals that most of the signature matches either occur at the beginning of TCP connections or directly after direction changes in the data streams. Their DPA approach exploits protocol semantics intrinsic to bidirectional communication, i.e., most application layer protocols rely on requests and associated responses with a direction change in the data stream in between.