IT and OT both use computers and networks, but they exist for different reasons. IT protects information. OT keeps a physical process running safely. That changes almost every security decision.
The key differences
| Topic | Office IT | Operational technology (OT) |
|---|---|---|
| First priority | Confidentiality of data | Safety, then availability of the process |
| Impact of an incident | Data loss, business disruption | Outage, equipment damage, environmental or safety harm |
| System lifetime | 3–5 years | 15–25 years or more |
| Patching | Regular, often automatic | Planned outages, vendor approval, sometimes not possible |
| Restarts | Routine | May trip a plant or interrupt supply |
| Protocols | Modern, authenticated | Industrial protocols, often without authentication |
| Testing | On live systems is common | Must be passive or offline; active scanning can crash devices |
| Ownership | IT department | Operations, engineering and vendors |
| Change | Fast | Controlled by engineering and safety management |
What this means in practice
- Availability comes first. A security control that might stop the process needs engineering approval and a fallback.
- Patch where you can, protect where you can't. When a controller can't be patched, segmentation, monitoring and strict access compensate.
- No active scanning on live plant without care. Many field devices respond badly to scans. OT assessments rely on documents, configuration review and passive monitoring unless the owner authorises more.
- Vendors are part of the system. Remote support, warranties and certified configurations constrain what the owner can change.
- Safety systems are special. Safety instrumented systems must stay independent and protected; cybersecurity and functional safety have to be considered together.
Where IT and OT must work together
The boundary between IT and OT, usually an industrial demilitarised zone (IDMZ), is where most attacks cross. Shared identity systems, remote access, backups and incident response all need IT and OT teams to agree who owns what. Good OT security starts with that agreement.