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BackWhat is Purdue Model in Operational Technology (OT)?
The Purdue Model is a reference architecture that organizes industrial control systems (ICS) into hierarchical levels based on their operational functions and communication requirements. Developed to support manufacturing and industrial automation, the Purdue Model helps organizations separate operational technology (OT) from information technology (IT), improving visibility, reliability, and cybersecurity.
The model is widely used in industries such as manufacturing, energy, oil and gas, water treatment, pharmaceuticals, and utilities. By defining clear boundaries between industrial assets and enterprise systems, the Purdue Model reduces unnecessary communication and helps limit the spread of cyber threats across industrial environments.
Why the Purdue Model matters
Industrial environments contain systems with different operational requirements. PLCs, sensors, and safety systems prioritize real-time control, while enterprise applications focus on business operations and data analytics. Placing all these systems on a flat network increases the risk of cyberattacks spreading across the environment.
The Purdue Model helps organizations:
- Segment IT and OT networks.
- Reduce the attack surface across industrial environments.
- Improve visibility into industrial assets.
- Limit lateral movement during cyberattacks.
- Support secure remote access and data exchange.
- Strengthen industrial cybersecurity architectures.
Network segmentation based on the Purdue Model is a common recommendation in OT security frameworks.
Purdue Model levels
The Purdue Model divides industrial environments into logical levels, each serving a specific operational purpose.
| Purdue level | Function |
|---|---|
| Level 0 | Physical processes, sensors, actuators, and field devices |
| Level 1 | Basic control systems, including PLCs and RTUs |
| Level 2 | Supervisory control systems such as HMIs and SCADA servers |
| Level 3 | Manufacturing operations, historians, and production management systems |
| Level 3.5 | Industrial DMZ that separates OT from enterprise IT networks |
| Level 4 | Enterprise IT systems such as ERP, email, and business applications |
| Level 5 | External networks, cloud services, and internet-connected resources |
Communication is typically controlled between adjacent levels to reduce security risks and maintain operational stability.
Purdue Model and industrial cybersecurity
The Purdue Model supports a defense-in-depth approach by separating critical operational systems from enterprise networks. Security teams can apply different controls at each level, including firewalls, network segmentation, access control, monitoring, and secure remote access.
While modern industrial environments increasingly exchange data with cloud platforms and IIoT services, many organizations continue to use the Purdue Model as the foundation for OT network design and then extend it to accommodate newer technologies.
How Hexnode supports Purdue Model environments
Hexnode XDR helps organizations secure the Windows endpoints that operate across Purdue Model environments, including engineering workstations, operator terminals, jump servers, and administrative systems. It collects endpoint telemetry, detects suspicious activity, and provides centralized visibility into threats and incidents, helping security teams identify compromised endpoints before attackers can move deeper into the OT network.
Hexnode XDR also supports response actions such as endpoint isolation and incident investigation. While it does not enforce Purdue Model segmentation or monitor industrial protocols directly, it strengthens the security of managed endpoints that interact with industrial control systems across multiple Purdue levels.
FAQs
Yes. Although cloud computing, IIoT, and edge computing have introduced new communication patterns, the Purdue Model remains a widely used framework for network segmentation and industrial cybersecurity planning.
Level 3.5 is the Industrial Demilitarized Zone (IDMZ), which acts as a buffer between enterprise IT and OT networks. It enables controlled communication while reducing direct exposure of industrial systems to enterprise or internet-based threats.
