Role-based access control (RBAC) multi-role system with four distinct user tiers—Admin, Executive, Coordinator, and Technician—each accessing role-specific modules through a centralized IAM and RBAC engine. Client devices connect via ISP and Internet through a hardened perimeter including external firewall, WAF, and load balancer, then authenticate at the Auth Server before reaching the VPN Gateway and internal firewall. The RBAC Engine enforces least-privilege access, routing authenticated users to their designated modules (Admin, Executive, Coordinator, Technician) with granular permissions to application servers, cache, object storage, and databases. This architecture demonstrates defense-in-depth with network segmentation, centralized identity management, and audit logging for compliance. Fork and customize this diagram on Diagrams.so to model your organization's role hierarchy, add additional user personas, or integrate with your identity provider.