The Purdue Model, a hierarchical model used to define OT network segmentation and cybersecurity best practices

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<Image Source: IEC62443-2-1 Reference architecture>

The Purdue Model for Industrial Control Systems (ICS) is a hierarchical model used to define industrial network segmentation and cybersecurity best practices. It was developed from the ISA-95 standard and is widely used in Operational Technology (OT) security frameworks.

Purdue Model – Overview

The Purdue model divides ICS architecture into six layers (Levels 0-5), structuring the communication flow between enterprise IT and industrial OT systems. The segmentation helps enhance security by restricting access between levels.

Purdue Model Levels and Their Functions

LevelFunctionDevices & ComponentsSecurity Considerations
Level 5 Enterprise NetworkCorporate operationsERP, Cloud Services, Email Servers, Internet AccessHigh risk from cyberattacks. Needs strong firewalls, endpoint security, and VPNs.
Level 4 Business/DMZIT-OT communication, data analysis, remote accessIT Databases, File Servers, Remote Access VPNsSegregation from OT networks via a firewall & DMZ. Only limited, monitored access.
Level 3 Operations
& Control Center
Centralized process monitoring & data exchangeHistorian, SCADA Servers, Remote Access Terminals, RTDB(Real-Time DB), PIMS(Plant Information Management System)Strict user authentication, endpoint protection, and network monitoring required.
Level 2
Process Control Network
Automated control, real-time monitoringHMI, EWS(Engineering Workstations), HIS, OPC ServersNetwork segmentation, intrusion detection (IDS), and least privilege access.
Level 1
Field Control(I/O)
Direct interface with industrial processesPLC, DCS ControllersProtection against unauthorized physical access and network threats.
Level 0 – Physical ProcessReal-world industrial operationsActuators, Motors, Valves, Pumps, Robots, Temperature & Pressure SensorsRequires tamper-proofing, physical security, and real-time monitoring.


#CPS #OT #XIoT #IoT #IIoT #IoMT #CPSSecurity #OTSecurity #IoTSecurity #CPS보안 #OT보안 #IoT보안

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