What is DMZ in SCADA Network: Definition and Use Cases

In a SCADA network, a DMZ (Demilitarized Zone) is a separate network zone that acts as a buffer between the corporate IT network and the SCADA control systems. It helps protect critical industrial devices by isolating them from direct access, allowing controlled communication and reducing security risks.

How It Works

Think of a DMZ in a SCADA network like a security checkpoint between two important areas: the office network and the industrial control systems. It creates a middle ground where only certain data and commands can pass through under strict rules.

This setup prevents direct access from the corporate network to the SCADA devices, which are often sensitive and critical for operations. The DMZ hosts servers like data historians or application gateways that collect and share information safely without exposing the control systems to potential threats.

By isolating these zones, the DMZ acts like a protective wall, reducing the chance that a cyber attack on the office network can reach the SCADA systems and cause damage.

Example

This example shows a simple firewall rule configuration that allows only specific traffic from the corporate network to the DMZ, and from the DMZ to the SCADA network.

bash

firewall-cmd --permanent --zone=dmz --add-source=192.168.10.0/24
firewall-cmd --permanent --zone=dmz --add-port=502/tcp
firewall-cmd --permanent --zone=internal --add-source=192.168.20.0/24
firewall-cmd --permanent --zone=internal --add-port=102/tcp
firewall-cmd --reload

Output

success
success
success
success
success

When to Use

Use a DMZ in SCADA networks when you need to securely connect corporate IT systems with industrial control systems without exposing critical devices directly. It is essential in environments where data needs to flow between office and control networks but security risks must be minimized.

Common use cases include:

• Allowing remote monitoring of SCADA data without risking control system access
• Hosting data historians or application servers that collect SCADA data for analysis
• Separating internet-facing services from sensitive control devices

Key Points

• A DMZ isolates SCADA systems from corporate networks to improve security.
• It acts as a controlled buffer zone for data exchange.
• Firewalls and strict rules govern traffic between zones.
• Helps prevent cyber attacks from reaching critical industrial devices.

Key Takeaways

A DMZ in SCADA networks protects critical control systems by isolating them from corporate networks.

It acts as a secure middle zone allowing controlled data flow between IT and SCADA systems.

Firewalls and strict access rules are essential to enforce DMZ security.

Use DMZs when remote monitoring or data collection is needed without exposing SCADA devices.

Proper DMZ setup reduces the risk of cyber attacks on industrial control systems.