Firewall Rule Matrix Generator

Firewall change requests often arrive as a few plain-language dependencies: a partner needs HTTPS to an API, an application server needs a database port, or an administrator needs temporary SSH during a migration. The policy that finally enforces that request is stricter than the wording in the ticket. It needs a source, destination, protocol, port or service, direction, action, owner, evidence, logging choice, and a review date that can survive engineering review and audit review.

A rule matrix turns those dependencies into a shared review format before anyone writes platform-specific policy. That matters because firewall platforms do not all express intent the same way. A zone firewall may care about from-zone and to-zone order, a cloud security group may only allow positive rules, a host firewall may need chain direction, and an application-aware firewall may treat a named application differently from a raw TCP port. The matrix gives reviewers one place to ask whether the traffic is narrow enough, whether the owner is accountable, and whether the row can be translated without changing the request's meaning.

Good matrix work separates requested connectivity from proof of safety. A narrow source can still be wrong if it points at the wrong object group. A valid ticket can still describe a stale exception. A service name can hide several ports, while a port number can hide an application that should be controlled by application identity instead of only by Layer 4 matching.

The finished matrix is not a deployment receipt. NAT, routing, object expansion, inherited policies, rule order, service tags, platform defaults, and connection-state behavior can all change the effective result. Treat the matrix as pre-deployment evidence: it should make weak rows visible early, then the final firewall or cloud control plane still needs its own verification.

How to Use This Tool:

Start with the flow rows, then tune the review context so the generated outputs match the platform and audience receiving the handoff.

1. Paste CSV-style text into Flow rows, drag a text or CSV file onto the field, or use Browse. The full column shape accepts source and destination zones, names, CIDRs, protocol, ports, action, application, reason, owner, ticket, expiry, and logging.
2. Use Sample when you want a quick model of the expected row layout. Headers are optional, quoted CSV cells are supported, comment lines beginning with # are ignored, and a shorter legacy source/destination shape can parse when the network fields are clear.
3. Choose Matrix profile and Target platform before interpreting findings. The target platform changes direction, construct, constraint, object, audit, and heatmap pressure guidance for Palo Alto, AWS security group, Azure NSG, Google Cloud VPC firewall, Cisco ASA, FortiGate, Linux host, or generic zone firewall review.
4. Set Object-group mode, Review audience, and Logging and enforcement profile to match the review. These controls affect whether object membership must be expanded, how audience notes are written, and whether logging, monitor-first, temporary-exception, or strict-enforcement findings are raised.
5. Use Default row action and Logging default for blank cells only. Explicit row values still take precedence, so an individual row can still say deny, monitor, off, or start and end.
6. Open Advanced when review IDs, sorting, ownership, or expiry timing need adjustment. Rule ID prefix, Matrix order, Fallback owner, and Expiry warning window change the generated rows without changing the original traffic intent.
7. Fix warning messages before sharing results. Invalid IP/CIDR-looking text is kept as a named object so the row is not lost, but scope findings are weaker until the address is corrected. When parsing succeeds, Normalize rewrites the input into the canonical CSV order for handoff.

Interpreting Results:

Read Risk in Review Matrix together with the matching rows in Rule Audit Queue. The score shows the strongest pressure found for a rule; the audit queue explains the evidence and the practical repair. Object Group Plan and Platform Handoff are translation aids, while the scope heatmap shows which zone pairs concentrate rule count and platform pressure.

A low score is not an approval. It only means the supplied text did not trigger the built-in breadth, service, governance, duplicate, expiry, logging, object-mode, or platform-profile checks. The final firewall, cloud network control, or host policy remains the authority for whether traffic will be allowed or denied.

Technical Details:

A firewall rule matrix is built around a traffic tuple. At minimum, the tuple needs source, destination, protocol or service, and action. Governance fields such as reason, owner, ticket, logging, and review date do not change packet matching, but they change whether a reviewer can defend the rule and revisit it later.

Address precision drives much of the risk. 0.0.0.0/0, ::/0, any, all, and * represent unrestricted scope. IPv4 addresses without a prefix are treated as host routes, IPv6 addresses without a prefix are treated as host-sized IPv6 entries, and CIDR prefixes become broader as the prefix gets shorter. Named objects are carried through the matrix because they may be valid platform objects, but their membership cannot be proven from row text alone.

Private IPv4 classification follows the RFC 1918 blocks 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. Other parsed IPv4 ranges are labeled as public, loopback, link-local, documentation, or multicast/reserved where the address pattern makes that clear. That label is a review clue, not a routing decision.

Formula Core:

Row risk is the strongest finding score for the row, capped at 100. Findings that are present but weaker stay visible in the audit queue without adding together into a larger number.

A broad source finding at 62, a missing owner finding at 18, and a close review-date finding at 38 produce 62/100. An unrestricted any-source, any-destination, any-service allow produces 96/100 because that single finding is stronger than the normal high-risk thresholds.

Rule Core:

Severity uses the highest applicable finding first. If no high-severity finding exists, numeric scores map to Critical at 85 or more, High at 60 or more, Medium at 35 or more, Low above zero, and Clear at zero.

The platform handoff notes are intentionally conservative. Security groups aggregate allow rules and do not model explicit deny rows the same way as ACLs. Azure NSGs use priority and direction, Google Cloud VPC firewall rules have direction and implied actions, and Palo Alto security policy often needs application-aware review rather than service-only matching. The matrix records those pressure points so the reviewer can translate the row deliberately instead of copying a generic permit line.

Advanced Tips:

• Choose Target platform before judging the highest-risk rows. The same flow can need different follow-up when it becomes an AWS security group rule, an Azure NSG rule, a Palo Alto security policy row, or a Linux host firewall entry.
• Use Matrix order deliberately. Input order preserves change-record parity, Risk first is better for review triage, and Specific first helps spot broad rows that could shadow narrower ones on ordered firewalls.
• Set Object-group mode to Expanded members required when named objects are not trusted evidence yet. That surfaces object-only source and destination values as review findings instead of treating labels as proven scope.
• Match Logging and enforcement profile to the review posture. High-visibility reviews expect stronger logging, temporary exceptions expect review dates, and monitor-before-enforce rows should not be treated as final permits.
• Use Expiry warning window to match the review calendar. The accepted range is 0 to 365 days, and dates inside the window become review findings even when the traffic scope is narrow.
• Run Normalize only after parser warnings are understood. The normalized CSV is useful for handoff, but invalid IP/CIDR-looking values should be corrected first so scope labels and heatmap pressure are meaningful.

Responsible Use Note:

Firewall flow text can expose internal addresses, hostnames, partner ranges, application names, owner teams, ticket numbers, and change windows. The visible workflow parses text and files in the browser and uses local downloads or clipboard actions for exports, but the data can still leak if it is pasted into shared systems or included in a shared page link.

• Use the smallest review slice that contains the traffic under discussion.
• Remove sensitive owner, ticket, hostname, or partner details before sharing output outside the review group.
• Do not treat generated rows as approved firewall changes without checking the final control plane, object membership, NAT, routing, inherited policy, and rule order.

Worked Examples:

Partner HTTPS ingress

A row such as Internet,Partner API,203.0.113.64/27,DMZ,api-lb,10.44.20.20/32,tcp,443,allow,https,Partner API ingress,appsec,CHG-2401,2026-08-31,on creates a scoped allow in Review Matrix. The row has a partner-sized source range, one host destination, TCP 443, a reason, an owner, a ticket, a review date, and logging. The expected follow-up is to confirm that the partner range and destination object are correct in the target platform.

Database access from an application subnet

App,checkout-api,10.44.30.0/24,Data,orders-db,10.44.40.10/32,tcp,5432,allow,postgresql,Checkout reads orders database,platform,CHG-2402,2026-09-30,on is narrow by destination but still touches a watched database port. If the source is broad for the environment, Rule Audit Queue can raise sensitive-service or broad-source evidence, and Object Group Plan should be checked for reusable source and service objects.

Expired break-glass SSH

A migration row from 10.44.99.10/32 to 10.44.40.10/32 on TCP 22 may have a tight source and destination, but an expiry date before today creates a High review-date finding. Risk can therefore be driven by governance evidence rather than address breadth, and the owner should renew, remove, or replace the row before it becomes long-lived access.

AWS security group deny row

If Target platform is AWS security group and a row uses action deny, Platform Handoff warns that the row should not be exported as a security group rule. The denial may belong in a network ACL, AWS Network Firewall policy, or an implicit-deny note depending on the design.

Invalid address cleanup

A source such as 10.44.300.5/32 is kept as named object text and a warning says the value is not valid IP/CIDR. Correct the address, rerun the review, and compare Risk, Object Group Plan, and Rule Scope Heatmap again because scope classification can change after the address parses.

FAQ:

Glossary:

Firewall rule matrix

A row-based review table that keeps each requested traffic flow, action, owner, approval reference, and review status together.

Traffic tuple

The source, destination, protocol, service, and action fields that define what a firewall rule can match.

CIDR

Address notation such as 10.44.20.20/32 or 203.0.113.64/27 that describes a host or network range.

Any service

A row with no effective protocol or port boundary, so the supplied service scope is unrestricted.

Rule shadowing

A condition where an earlier broader row may match traffic before a later narrower row on ordered firewalls.

Implicit deny

A policy behavior where unmatched traffic is blocked even without a visible deny row.

Object group

A reusable source, destination, or service object candidate derived from repeated matrix values.

References:

• Guidelines on Firewalls and Firewall Policy, National Institute of Standards and Technology, September 2009.
• RFC 1918: Address Allocation for Private Internets, RFC Editor, February 1996.
• Security group rules, Amazon VPC User Guide.
• Azure network security groups overview, Microsoft Learn, July 15, 2025.
• VPC firewall rules, Google Cloud Documentation.
• Safely Enable Applications on Default Ports, Palo Alto Networks, May 28, 2026.
• How to allow a service in firewalld, Simplified Guide.
• How to allow a port with iptables, Simplified Guide.