Revisiting the Relevance of the Industrial DMZ (iDMZ)
If you enter the term “Purdue Model” into your favorite search engine, the resulting images will vary considerably. There’s almost no better way to stir up an Operational Technology (OT) security conversation than to begin debating what belongs on Level 1 or Level 3 of the model. You might even find some diagrams place operator Human-Machine Interfaces at Level 3. Notably, the original 1990 publication defines “operator’s console” as a Level 1 entity.