Rule Set Input
Add multiple rules, then run detection. Priorities are evaluated from lowest to highest.
Example Data Table
These examples demonstrate shadowing, contradiction, and overlap patterns.
| Priority | Name | Direction | Source | Destination | Protocol | Ports | Action |
|---|---|---|---|---|---|---|---|
| 10 | Allow HTTPS to Web | Inbound | any | 10.10.20.0/24 | TCP | 443 | Allow |
| 20 | Deny Web Subnet (legacy) | Inbound | any | 10.10.20.0/24 | TCP | any | Deny |
| 30 | Allow Admin SSH | Inbound | 10.0.5.0/24 | 10.10.30.10 | TCP | 22 | Allow |
| 40 | Allow SSH Broad | Inbound | 10.0.0.0/8 | 10.10.30.10 | TCP | 22 | Deny |
Formula Used
Each rule is treated as a set of packets defined by:
- Direction ∈ {Inbound, Outbound, Any}
- Source = CIDR range (network to broadcast)
- Destination = CIDR range (network to broadcast)
- Protocol ∈ {TCP, UDP, ICMP, Any}
- Ports = [pmin, pmax] (for TCP/UDP)
Containment: A contains B if every field in A covers B:
Overlap: A overlaps B if their ranges intersect in every applicable field. Conflict types are then assigned using containment, overlap, action, and priority order.
How to Use This Calculator
- Enter each rule with priority, direction, source, destination, protocol, ports, and action.
- Use any to represent all addresses or all ports.
- Click Detect Conflicts to generate results above the form.
- Review shadowing and contradictions first, then clean duplicates and redundancies.
- Use Download CSV for spreadsheets and Download PDF for shareable reports.
Why rule conflicts matter in real environments
Security teams manage firewalls, cloud security groups, WAF filters, and application allowlists at once. Under time pressure, exceptions pile up and intent becomes unclear. A shadowed deny can leave traffic open, while duplicate allows inflate reviews. This detector compares rules using direction, source, destination, protocol, and ports, then highlights coverage and overlap relationships. The output helps auditors and engineers discuss facts, not assumptions.
Data fields that drive accurate comparisons
Inputs are normalized so different formats still compare correctly. IP values are treated as CIDR ranges, and any maps to 0.0.0.0/0. Ports accept single numbers or ranges, such as 443 or 1000-2000. Protocol selection separates TCP and UDP behavior, and direction distinguishes ingress from egress. Priority is essential because many engines evaluate top to bottom.
How the detector classifies conflicts
Duplicates appear when every match field and the action are identical. Contradictions occur when match fields match but actions differ. Redundancy is reported when an earlier rule fully covers a later rule with the same action, suggesting safe removal. Shadowing is flagged when an earlier covering rule uses a different action, making the later rule effectively unreachable. Overlap conflicts are partial intersections with different actions.
Operational metrics you can track over time
Track counts per deployment window: duplicates, redundancies, shadowed rules, and overlap conflicts. Measure average priority distance for shadowing pairs to learn where policy ordering breaks down. Compare allow versus deny ratios by zone to spot over-permissive segments. CSV exports support dashboards, and periodic PDFs provide evidence for compliance reviews and risk committees. When redundancy stays high, consider templates and centralized ownership. When overlap rises, add pre-deployment linting and peer review. Over time, lower conflict density correlates with faster incident triage and clearer blast-radius analysis during outages and post-change investigations overall.
Recommended remediation workflow for faster hardening
Fix shadowed and contradictory rules first because they change enforcement. Next, remove duplicates and proven redundancies after testing. For overlaps, either split by port or subnet, or adjust priority to align intent. Record a short reason for each edit, then re-run the detector to confirm improved consistency. Repeat after major migrations, vendor changes, and segmentation projects.
FAQs
Does priority change the conflict result?
Yes. Shadowing and redundancy depend on evaluation order. If an earlier rule fully covers a later rule, the later rule may be redundant or unreachable, depending on the action.
What formats are supported for IP ranges?
Use CIDR notation like 10.0.0.0/24, single IPs like 10.0.0.5, or the word any. The detector normalizes inputs to comparable ranges.
How are ports compared across rules?
Ports can be a single value or a range such as 80-90. A range is considered broader than a single port, and overlaps are detected when ranges intersect.
Why do I see overlap conflicts with different actions?
Two rules can match some of the same traffic but apply different actions. This can produce inconsistent behavior across devices or future edits, so it is flagged for review.
Can I use this for cloud security groups?
Yes, as long as your rules can be expressed with direction, CIDR, protocol, and ports. Translate vendor terms into these fields, then compare for redundancy and overlap.
Is the exported PDF suitable for audits?
The PDF includes inputs, detected conflict types, and a timestamp. For formal audits, attach it to the change ticket and keep the underlying rule source as supporting evidence.