AWS Firewall Manager (FMS) | Overview.

AWS Firewall Manager (FMS) - Overview.

Scope:

• The Concept of AWS Firewall Manager,
•  Core Architecture & Flow (A fits into AWS Security Ecosystem),
• Table of Key Components in Architecture & Description,
• Table for Supported Services/Layers, Policy Types & Description,
•  How aws firewall manager Works (Step-by-Step),
• Sample Use Cases,
• Table for Integration Services & Roles,
• Best Practices.

 The Concept of AWS Firewall Manager

• AWS Firewall Manager (FMS) is a Centralized Security Management Service.
• AWS Firewall Manager (FMS) lets twtech:
•  Define and enforce security policies for:
•  AWS WAF, 
• AWS Shield Advanced, 
• VPC security groups, 
• Route 53 Resolver DNS Firewall, 
• AWS Network Firewall
•  Automatically apply those policies across all accounts and resources in twtech AWS Organization (via AWS Organizations).
•  Maintains consistent protection for new and existing resources without manual setup in every account.

 Core Architecture & Flow (A fits into AWS Security Ecosystem):

Table of Key Components in Architecture & Description:

Component	Description
Admin Account	The central account (designated via AWS Organizations) that defines and manages policies.
Member Accounts	Other accounts in the org where FMS applies and enforces policies.
Policies	Define rules and targets for specific AWS services (e.g., WAF Web ACLs or Shield protections).
Compliance Reports	Show which resources are protected, missing policies, or are non-compliant.

 Table for Supported Services/Layers, Policy Types & Description

Service / Layer	Firewall Manager Policy Type	Description
AWS WAF	Web ACL Policy	Applies WAF Web ACLs to CloudFront, ALBs, or API Gateways.
AWS Shield Advanced	Shield Policy	Enrolls resources into Shield Advanced protection automatically.
Security Groups	Security Group Policy	Manages common rules or audits unused/permissive SGs.
AWS Network Firewall	Network Firewall Policy	Deploys centralized firewall rules in VPCs.
Route 53 Resolver DNS Firewall	DNS Firewall Policy	Enforces DNS filtering rules organization-wide.
Third-party Firewalls (via Marketplace)	Custom Policy	Integrate vendor-managed security controls.

 How aws firewall manager Works (Step-by-Step)

1. Enable AWS Organizations
• Create or use an existing AWS Organization.
• Designate the management account.
2. Enable Firewall Manager
• Choose an admin account for Firewall Manager.
3. Define a Policy
• Choose policy type (e.g., WAF, Shield, SG, NF, etc.).
• Define rules and scope (resource type, tags, regions).
4. Automatic Enforcement
• FMS identifies all matching resources across member accounts.
• It automatically applies and maintains policies.
• New resources matching the scope are automatically protected.
5. Compliance Monitoring
• FMS dashboards and reports show compliant vs. non-compliant resources.
• Integrates with AWS Security Hub for centralized visibility.

 Sample Use Cases

Scenario	How FMS Helps
Consistent WAF protection	Apply a single WAF Web ACL to all CloudFront distributions.
DDoS protection for all apps	Automatically enroll new ALBs into Shield Advanced.
Restrict open Security Groups	Detect and optionally remediate overly permissive SGs (e.g., 0.0.0.0/0:22).
Centralized VPC Firewalling	Apply AWS Network Firewall policies to all new VPCs.
DNS threat filtering	Apply Route 53 DNS Firewall rulesets org-wide.

 Table for Integration Services & Roles

Service	Integration Role
AWS Organizations	Enables multi-account enforcement
AWS Config	Tracks compliance state
AWS Security Hub	Aggregates findings
CloudWatch & EventBridge	Sends compliance alerts
AWS Shield Advanced	Manages DDoS coverage
AWS WAF / Network Firewall	Enforces rule sets

Best Practices

1. Use AWS Organizations with SCPs → Ensure accounts cannot disable FMS or change policies locally.
2. Tag resources consistently → FMS uses tags to determine which resources a policy applies to.
3. Integrate with Security Hub → Centralize compliance visibility across all AWS services.
4. Enable Shield Advanced via FMS → Automatically cover all critical workloads.
5. Test policies in one OU first → Then expand gradually across OUs for safe rollout.