Passive Monitoring & Active Collection for a Complete OT Asset Inventory

### Executive Summary This report outlines Dragos’ recommended approach to OT asset inventory: a passive-first architecture using deep packet inspection and network sensors to establish continuous, non-intrusive visibility, supplemented by controlled, read-only active collection (EV Agent) to fill coverage gaps and enrich asset details. It emphasizes the operational constraints of industrial environments, the importance of a living inventory for detection and response, and the benefits to vulnerability management and incident investigations while stressing coordination with operations to avoid disrupting safety or reliability.