Firewall Rule Analysis (VMware vDefend Firewall)

This explains how Firewall Rule Analysis helps teams review, optimize, and clean up firewall rules automatically, either in real time or on a schedule.

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What Rule Analysis Does

• Analyzes firewall rules regularly or on demand

• Detects configuration problems (anomalies)

• Provides detailed reports and guidance

• Helps improve firewall performance, security, and manageability

All parts of a rule are analyzed, including:

• Source

• Destination

• Service

• Profile

• Applied-to scope

• Action (allow/drop/reject)

• Direction

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Types of Firewall Rule Anomalies Detected

1. Duplication

• Two or more rules are exactly the same

• Creates unnecessary clutter

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2. Contradiction

• Rules match the same traffic but have different actions

• Example: one rule allows traffic, another blocks it

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3. Shadowing

• A rule is never used because a higher-priority rule already matches the traffic

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4. Redundancy

• Rules match the same traffic and have the same action, but one is unnecessary

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5. Permissiveness

• Rules that are too open

• Example: source = any, destination = any, service = any, action = allow

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6. Irrelevance

• Rules that never match any traffic

• Often caused by empty or incorrect source, destination, or applied-to fields

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7. Consolidation

• Multiple rules that can be merged into one

• Same action, only one field differs (source, destination, or service)

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Reporting & Scheduling

• Each anomaly type generates a separate CSV report

• Reports can be:

  • Run automatically (weekly by default)

  • Run manually at any time

• Scheduling options:

  • Weekly

  • Monthly

  • Quarterly

• Reports can be downloaded and reviewed offline

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Ignoring Specific Rules

• Certain rules can be excluded from analysis

• Useful for:

  • Temporary rules

  • Known exceptions

• Managed via the “Manage Ignored Rules” option

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Key Benefits

• Cleaner and more efficient firewall configurations

• Reduced misconfigurations and security risks

• Faster audits and troubleshooting

• Easier ongoing firewall maintenance

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Final Takeaway

Firewall Rule Analysis helps eliminate duplicate, conflicting, unused, and risky rules—making your firewall simpler, safer, and easier to manage.

With VMware vDefend Firewall, rule analysis turns complex firewall management into a guided, automated process.