L4 L7 Verb-Based Firewall Context Accumulation
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Solution Overview
Problem
Traditional firewalls only process data packets based on information from headers, missing critical insights from payloads, which limits their filtering capabilities and efficiency.
Innovation Solution
Implementing an L4, L7, and verb-based firewall in a software-defined network that processes and enforces rules on both Layer 4 and Layer 7 data, including payloads, using a virtual network interface card executed by a hypervisor, allowing for multi-facet filtering and dynamic Deep Packet Inspection (DPI) analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional firewalls only process header data, then processing speed is maintained, but filtering accuracy and security effectiveness deteriorate
Solution Approach 1:
The patent implements selective DPI analysis where packets are subjected to partial or full deep packet inspection based on matching rules. Not all packets undergo complete payload analysis - only those that match specific L7 protocol patterns or require verb-based rule evaluation. This partial action approach maintains processing speed for simple packets while achieving high filtering accuracy for complex security threats.
Solution Approach 2:
The firewall processing is segmented into multiple layers: L4 transport layer processing for basic header analysis, L7 application layer processing for protocol-specific analysis, and verb-based rule processing for application-specific commands. Each layer handles specific aspects of packet inspection, allowing parallel processing paths that maintain speed while improving accuracy through comprehensive multi-layer analysis.
2Reliability
If deep packet inspection is performed on all packets, then filtering accuracy improves, but processing overhead and time consumption increase
Solution Approach 1:
The system performs DPI only when necessary - when L7 protocol matching indicates potential security concerns or when verb-based rules require payload analysis. Most routine packets matching L4 rules bypass extensive DPI, reducing processing time while maintaining security effectiveness for suspicious traffic.
Solution Approach 2:
The firewall uses feedback from L4 header analysis to determine the scope of L7 DPI required. If header analysis indicates a packet matches known safe patterns, DPI is minimized or skipped. If headers show potential threats or require application-layer verification, DPI is escalated accordingly, creating an adaptive processing time based on actual security needs.
3Adaptability or versatility
If only Layer 4 rules are enforced, then processing simplicity is maintained, but security coverage and rule granularity deteriorate
Solution Approach 1:
The firewall architecture is segmented into distinct processing modules: L4 transport layer rule engine, L7 application layer protocol parser, and verb-based rule evaluator. Each module handles specific rule types with appropriate granularity - L4 for basic connectivity, L7 for protocol-specific control, and verb-based for application command filtering. This segmentation provides fine-grained security control while keeping each module's complexity manageable.
Solution Approach 2:
The firewall implements a universal ruleset structure where L4, L7, and verb-based rules can be interleaved and combined in a single processing pipeline. The same packet can be evaluated against multiple rule types sequentially, providing versatile security coverage from simple port filtering to complex application command control without requiring separate firewall systems.
Data Source
AI summary
The method for implementing mechanisms for Layer 7 context accumulation for enforcing Layers 4, 7, and verb-based rules is presented. The method comprises: receiving stream data, and identifying a packet in the stream. If the packet includes Layer 7 headers: for each Layer 7 header: determining content of the packet identified by a Layer 7 header's identifier; and parsing the content to extract firewall input data. If one or more rules at least partially match the firewall input data, determining that a particular rule also includes additional information that cannot be found in the firewall input data; performing a DPI on the content to determine whether at least a portion of the additional information is found in the content; extracting additional input data from the content and adding it to the firewall input data; and applying the rules to the firewall input data to process the packet.