Cybersecurity
Operational technology security for control systems, written for the people who actually maintain them.
Written guides in this section
Full references, procedures, and diagnostic guides published under Cybersecurity.
IEC 62443
The international standard series for industrial automation and control system security: how it is organized, what security levels and foundational requirements mean, and how a utility or integrator actually uses it.
11 min readUpdated Sep 5, 2026
OT Risk Assessment
Ranking what could go wrong in a control system and what it would cost: the consequence-first method for utilities, the assets and scenarios to list, likelihood without pretending to know it, the risk matrix, and turning the ranked list into a work plan.
10 min readUpdated Sep 5, 2026
Security Program Basics
What a control system security program is for a utility that has never had one: a named owner, an inventory, a risk assessment, a few policies, baseline controls, training, vendor rules, an exercised incident plan, and a first-year plan for a small staff.
10 min readUpdated Sep 5, 2026
Zones and Conduits
The IEC 62443 way to segment a control system: grouping assets into zones with a shared security level, inventorying every conduit between them, and turning the drawing into firewall rules. With a worked water utility example.
12 min readUpdated Sep 5, 2026
VLAN Segmentation
Using VLANs to build the zones of a control network on shared switches: what a VLAN separates and what it does not, the zone-to-VLAN mapping, trunks and the native VLAN, routing only through a firewall, and where separate hardware begins.
9 min readUpdated Sep 5, 2026
Industrial DMZ Design
The buffer zone between the business network and the control system: what goes in it, the no-direct-path rule, push-not-pull data flows, the firewall pair, and the services a utility actually needs to place there.
10 min readUpdated Sep 5, 2026
Browse Cybersecurity
OT Security
The fundamentals that everything else rests on.
5 topics
Network Segmentation
Separating the control network from everything else.
5 topics
Remote Access
Letting people in without leaving the door open.
5 topics
Firewalls
Rules, placement, and review.
4 topics
PLC Security
Protecting the device that moves the equipment.
5 topics
SCADA Security
Hardening the supervisory layer.
5 topics
Passwords & Credentials
The most common finding in every OT assessment.
4 topics
Backups
The control that actually gets a plant back online.
5 topics
Change Detection
Knowing when something moved.
3 topics
Incident Response
Planning for the day it happens.
5 topics
Asset Inventory
You cannot protect what you have not listed.
3 topics
Vulnerability Management
Handling advisories on equipment you cannot reboot.
3 topics
Water/Wastewater Cybersecurity
Sector-specific guidance for water and wastewater utilities.
5 topics
Direct contact
Have a controls question?
Reach Eric Sullivan directly about anything on this site, a controls or automation topic, or one of his personal projects.
References to manufacturers, products, model numbers, software platforms, technical specifications, companies, standards organizations, or other organizations are provided for informational purposes and do not imply sponsorship, endorsement, authorization, or affiliation unless expressly stated. Manufacturer specifications must be independently verified against current manufacturer documentation.