Open Source Firewall Policy Analyzer Calculator
Measure policy quality with transparent weighted scoring. Spot redundant, shadowed, risky, and overly broad rules. Plan cleaner changes with evidence, exports, graphs, and summaries.
Firewall Policy Inputs
Example Data Table
| Metric | Example Value |
|---|---|
| Total Rules | 320 |
| Shadowed Rules | 24 |
| Redundant Rules | 31 |
| Overly Permissive Rules | 17 |
| Unused Rules | 29 |
| Critical Assets Affected | 15 |
| Monthly Change Frequency | 14 |
| Documentation Quality | 68% |
| Days Since Review | 120 |
| Exception Rules | 11 |
| Calculated Risk Score | 16.39 |
| Calculated Health Score | 90.41 |
| Calculated Policy Efficiency | 91.25% |
| Calculated Review Hours | 38.85 |
| Risk Band | Low |
Formula Used
This analyzer uses a weighted scoring model. Each policy weakness is converted into a normalized ratio, then multiplied by a severity weight.
Risk Score = (Shadow Ratio × 15) + (Redundant Ratio × 10) + (Permissive Ratio × 25) + (Unused Ratio × 10) + (Exception Ratio × 10) + (Critical Exposure × 15) + (Review Age Penalty × 10) + (Change Pressure × 5)
Health Score = 100 − Risk Score + Documentation Bonus
Policy Efficiency = 100 − average of shadowed, redundant, and unused rule percentages
Cleanup Priority Index = (Shadowed × 1.5) + (Redundant × 1.2) + (Unused × 1.1) + (Overly Permissive × 2.0) + (Exception Rules × 1.3)
Estimated Review Hours = (Total Rules × 0.08) + (Shadowed × 0.20) + (Overly Permissive × 0.30) + (Critical Assets × 0.15) + (Exception Rules × 0.10)
The model is vendor-neutral. It works well for open rule reviews, audit preparation, cleanup planning, and change control prioritization.
How to Use This Calculator
- Enter the total number of active firewall rules.
- Add counts for shadowed, redundant, overly permissive, unused, and exception rules.
- Enter how many critical assets are exposed by risky policy paths.
- Add monthly change volume, documentation quality, and days since the last full review.
- Click Analyze Policy to generate the score summary.
- Review the chart to see which factors contribute most.
- Download the results as CSV for records.
- Use the PDF button to save a formatted report snapshot.
FAQs
1. What does this calculator measure?
It estimates firewall policy quality using weighted risk factors. It highlights shadowing, redundancy, broad permissions, stale reviews, documentation gaps, and cleanup effort.
2. Is this tied to one firewall vendor?
No. The scoring model is vendor-neutral. You can use it with many platforms as long as you can count policy conditions and rule quality indicators.
3. Why are permissive rules weighted more heavily?
Broad allow rules often create larger blast radius. They can expose many services or hosts, so the model assigns them stronger penalty weight.
4. What is a shadowed rule?
A shadowed rule is effectively hidden by an earlier rule. Traffic matches the earlier rule first, so the later rule never has practical effect.
5. How should I interpret the Health Score?
Higher health means better policy maintainability and lower calculated risk. Good documentation can raise health, but large policy issues still reduce it.
6. Can this replace a full rule recertification?
No. It is a planning and triage tool. Use it to prioritize reviews, then confirm findings with logs, owners, change records, and formal approvals.
7. What input source is best for this analyzer?
Use exports from rule review platforms, SIEM reports, hit counts, policy recertification notes, and configuration comparisons from your environment.
8. When should I rerun the calculation?
Rerun it after major rule changes, quarterly audits, cleanup projects, exception reviews, or whenever business-critical assets are newly exposed.