OPC UA Deep Dive (Part 3): Exploring the OPC UA Protocol

This Part 3 article of Team82’s OPC UA Deep Dive series provides a concise technical overview of the OPC UA protocol: its three-layer architecture (application, session, transport), message types (HEL, OPN, MSG, CLO), message framing and header fields, transport options and common ports, secure channel/session establishment, security modes/policies, and authentication considerations. It is an informational/protocol-focused guide rather than a report of an incident or active threat.