While the Purdue Model defines how industrial systems are structured, true cybersecurity comes from how those layers are protected and interconnected. Each level of the model represents not only a functional boundary but also a security boundary.

• Segmentation is key: isolate levels to reduce risk.
• Defense-in-depth approach:
  • Firewalls between IT and OT
  • Network segmentation and VLANs
  • Monitoring and intrusion detection systems
  • Role-based access control (RBAC)