Firewall Rule Review

 

A Firewall Rule Review is a detailed inspection of firewall rules to ensure they are secure, effective, optimized, and aligned with your organization’s security policies and compliance requirements. The goal is to reduce the attack surface, eliminate unnecessary access, and enforce least privilege principles.

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🔍 Firewall Rule Review – Table Format

Here's a standard review table you can use to audit firewall rules:

#	Rule Name / ID	Source	Destination	Port / Service	Action	Risk Level	Status	Comments / Recommendations
1	Allow-HTTP	10.0.10.0/24	192.168.1.10	TCP 80	Allow	Medium	OK	Restrict to known internal web servers only
2	Allow-SSH-All	Any	10.0.1.5	TCP 22	Allow	High	Needs Revision	Limit SSH to trusted IPs or jump servers
3	Deny-All	Any	Any	Any	Deny	Low	OK	Proper default deny rule
4	Temporary-Test	192.168.100.0/24	10.10.10.10	Any	Allow	High	Expired	Remove or disable—temporary rule is outdated
5	DNS-Outbound	Internal Network	8.8.8.8	UDP 53	Allow	Medium	OK	Consider local resolver to reduce external lookup
6	Admin-Access	Office IPs	Firewall Mgmt IP	HTTPS (TCP 443)	Allow	Low	OK	Limit to specific subnets, confirm 2FA is used
7	Web-Server-DMZ	Any	DMZ Web Server IP	TCP 443	Allow	Medium	OK	Ensure WAF is in place; apply Geo-IP filter

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✅ Key Review Areas

1. Rule Justification
• Is the rule necessary?
• Who requested it and when?
2. Scope Minimization
• Are “ANY” or wide subnets used?
• Can it be narrowed to specific IPs or ports?
3. Rule Order Optimization
• Is the rule placed efficiently to avoid processing delays or incorrect matches?
4. Temporary Rules
• Are there any test/migration rules still active?
5. Shadowed / Redundant Rules
• Is there a rule that will never be triggered because of a previous rule?
6. Logging & Monitoring
• Are logs being generated for accepted and denied traffic?
• Are critical rules monitored in the SIEM?

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🛠 Tools to Assist with Rule Review

Tool	Purpose
Tufin	Automated rule analysis and risk scoring
FireMon	Rule cleanup, compliance enforcement
AlgoSec	Flow simulation and firewall optimization
Nipper	Configuration analysis for multiple firewall types
Manual CLI/GUI Review	For Cisco ASA, Palo Alto, Fortinet, Check Point etc.

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📄 Deliverables from a Firewall Rule Review

Document	Description
Rulebase Audit Report	List of rules, risks, and recommendations
Exception Report	Temporary or high-risk rules that require formal exceptions
Change Recommendation Log	Detailed actions for rule modifications or removals
Before/After Comparison	Optional, after implementing rule changes
Compliance Mapping Sheet	Maps firewall rules to frameworks like ISO, PCI, NIST

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Would you like a customizable Excel template for rule reviews, or help reviewing a rulebase from a specific firewall vendor (e.g., Palo Alto, Fortinet, Cisco ASA)?