A historian creates an unintended second route
A fictional plant separates an enterprise network from a process-control zone through a documented industrial boundary. A historian receives an additional network connection so office users can retrieve reports more easily. Its actual forwarding and service configuration has not been assessed, and a vendor maintains a separate remote-access account. A manager says the original firewall diagram proves the control zone remains isolated. This written review sends no packets and changes no device. Identify the new trust paths and the evidence required to establish the actual architecture, and explain why useful report access should be designed around necessary bounded flows rather than an unexamined bridge between networks.
1. What must be assessed?
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Actual interfaces, forwarding, permitted services, vendor access and the relationship to the intended boundary and process dependencies.
2. What design principle follows?
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Provide only the authorized needed exchanges through an appropriate reviewed boundary, accounting for the full workflow and bypass paths.