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OPTWALL: A Hierarchical Traffic-Aware Firewall. Mehmud Abliz, Subrata Acharya, Bryan Mills, Taieb Znati University of Pittsburgh, PA. Albert Greenberg, Microsoft Research, WA Jia Wang, Zihui Ge, AT&T Research, NJ. Introduction
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OPTWALL: A Hierarchical Traffic-Aware Firewall Mehmud Abliz, Subrata Acharya, Bryan Mills, Taieb ZnatiUniversity of Pittsburgh, PA Albert Greenberg, Microsoft Research, WA Jia Wang, Zihui Ge, AT&T Research, NJ • Introduction • The overall efficiency, reliability, and availability of a firewall is crucial in enforcing and administrating security. • The continuous growth of the Internet, coupled with increasing sophistication of the attacks, is placing stringent performance demands of firewall. Main approach for improving firewalls – rule optimization. Yet optimizing firewalls is hard, because • NP hard problem, hence not suitable for large number of rules • Need to maintain policy integrity OPTWALL Results Splits rule set hierarchically into multiple rule sets to reduce the average time for matching a packet to a rule. Provides an adaptation scheme which can dynamically change priority of a rule based on the traffic. How does a typical firewall works A typical present day firewall enforces its security policies via a set of multi-dimensional packet filters (usually a list of rules). Traffic gets filtered by this list following the “first hit” principle. • OPTWALLSplitting Approaches • Optimal Approach (A*) • Heuristic Solution (Greedy) • Initial filter determination • Hit count - Hit count • Hit count – Maximum distance • Random – Random • Maximum distance – Maximum distance • Our Goal • Improve the performance of firewall via • Reducing the average time the firewall spend on matching a packet to a rule in its rule set • Preserve the semantics of the original rule set • Efficiently prevent attacks, especially denial of service attack, via maintaining the optimality of the rule set as traffic patterns and rule sets change • Conclusion • Study the problem of decentralized multi- dimensional firewall optimization • Present OPTWALL, a hierarchical traffic aware framework for firewall optimization • Adaptive anomaly detection/counteraction mechanism • Nearly 35% improvement in operational cost of firewalls in worst case for a heavily loaded firewall operation • Evaluation Metric • Cost of a rulei • cost (rulei) = hit-count (rulei) * sum (size ( rulei)...size (rulei-1)) This work has been accepted to NDSS 2007. Poster designed by Mehmud Abliz.
