Network Engineering
Firewall Rule Analyzer
Enter firewall rules to check for wildcard source/destination, evaluation order conflicts, missing implicit deny, and common security misconfigurations.
No data is transmitted — everything runs locallyTool
About this tool
Firewall Rule Analyzer
The Firewall Rule Analyzer checks rule sets for wildcard sources/destinations, evaluation order conflicts, shadowed deny rules, and missing implicit deny-all.
• Audit firewall rules for 0.0.0.0/0 source before a security review
• Check whether a deny rule is shadowed by an earlier allow rule
• Verify that an implicit deny-all is effective at the end of a ruleset
• Detect unnecessarily broad port ranges in a firewall configuration
Next step
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Open Bandwidth-Delay Product Calculator →
FAQ
What does this tool tell you?
The Firewall Rule Analyzer checks rule sets for wildcard sources/destinations, evaluation order conflicts, shadowed deny rules, and missing implicit deny-all.
What affects the result most?
Rule evaluation order: first-match-wins (iptables, pf) vs last-match-wins (legacy ACLs). Allow/deny logic: explicit allow required; implicit deny-all at end is best practice. Source/destination validation: 0.0.0.0/0 matches everything — flag for review.
How should I use the result?
Treat the tool's output as a first-pass check, not a proof of correctness. A clean pass means no issues in the patterns this tool recognizes; a failure points to a specific problem you can investigate in your source. The underlying spec is the authoritative source for edge cases.