Firewall Rule Reordering for Packet Processing Delay Reduction
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Solution Overview
Problem
Network firewalls face performance bottlenecks due to complex rule sets and increasing traffic loads, leading to delays and susceptibility to Denial of Service (DoS) attacks, as traditional sequential rule evaluation methods are inefficient and not scalable.
Innovation Solution
The method involves reordering firewall rules to minimize the average number of comparisons required to determine an action while maintaining policy integrity, using a Directed Acyclical Graph (DAG) representation to preserve precedence relationships and sorting rules based on non-increasing probabilities, which can be implemented in hardware, software, or firmware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sequential rule evaluation is used to maintain policy integrity, then security policy correctness is preserved, but packet processing delay increases and performance deteriorates
Solution Approach 1:
The patent pre-calculates and stores the probability of packet matching for each firewall rule before evaluation. This preliminary preparation allows the system to quickly determine which rules are most likely to match incoming packets, enabling optimized evaluation ordering without compromising policy integrity. The pre-computed probabilities guide the reordering process to evaluate high-probability rules first, reducing average processing delay while maintaining correctness.
Solution Approach 2:
The patent dynamically reorders firewall rules based on their matching probabilities, transforming the static sequential evaluation into a dynamic, adaptive process. Rules are reordered so that those with higher probabilities of matching incoming packets are evaluated first, while maintaining the precedence constraints required for policy integrity. This dynamic adaptation allows the system to optimize performance based on actual traffic patterns and rule characteristics.
2Adaptability or versatility
If rule sets become more complex to handle diverse traffic, then security coverage is improved, but processing load increases and scalability deteriorates
Solution Approach 1:
The patent changes the evaluation parameter from simple sequential order to probability-based ordering. By computing and utilizing matching probabilities for each rule, the system can evaluate complex rule sets more efficiently. This parameter change allows the firewall to handle diverse traffic patterns and complex security policies while improving processing throughput, as the optimized evaluation order reduces the average number of rule comparisons needed.
3Reliability
If traditional sequential evaluation is used to ensure security correctness, then policy compliance is maintained, but the system becomes susceptible to DoS attacks and performance degrades
Solution Approach 1:
The system performs preliminary analysis to compute matching probabilities for each rule, identifying which rules are most likely to be encountered in normal traffic versus attack traffic. This preliminary preparation enables the firewall to quickly evaluate high-probability rules first, reducing the processing time for legitimate packets and making the system more resistant to DoS attacks that rely on forcing evaluation of many rules.
Solution Approach 2:
The patent implements dynamic rule reordering that adapts to traffic patterns while maintaining policy compliance. By continuously optimizing the evaluation order based on matching probabilities, the system can respond to varying traffic conditions and attack patterns, maintaining both security correctness and resistance to DoS attacks. The dynamic nature allows the firewall to prevent performance degradation even when facing malicious traffic designed to exploit sequential evaluation.
Data Source
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AI summary
Methods, systems, and computer program products for firewall policy optimization are disclosed. According to one method, a firewall policy including an ordered list of firewall rules is defined. For each rule, a probability indicating a likelihood of receiving a packet matching the rule is determined. The rules are sorted in order of non-increasing probability in a manner that preserves the firewall policy.