Designing safer links: secure connectivity for operational technology

Summary

The National Cyber Security Centre (NCSC) has published new guidance: “Secure connectivity principles for operational technology (OT)”. The guidance builds on earlier advice about creating and maintaining a definitive view of OT architecture and provides eight core principles to help organisations design, review and secure connectivity within and to OT systems.

The principles emphasise risk-aware connectivity decisions, limiting exposure, hardening boundaries, and ensuring logging and monitoring. They are practical goals rather than check-box rules and are illustrated with worked examples such as safe data sharing with OEMs. The guidance was developed with international partners and informed by industry experience working with operators of essential services.

Key Points

The NCSC published “Secure connectivity principles for OT” to translate visibility into actionable design choices.
The guidance contains eight core principles covering risk/opportunity balance, limiting exposure, boundary hardening, logging and monitoring, and centralisation of connections.
It builds on earlier NCSC guidance about creating a definitive view of OT architecture — you need that visibility first to act effectively.
Practical worked examples (for example, safe OT data sharing with OEMs) show how to implement the principles in real-world scenarios.
The guidance was produced with international partners (CISA, ASD, FBI, Cyber Centre Canada, NCSC-NZ, NCSC-NL, BSI), reflecting broad consensus and applicability.

Context and relevance

OT environments (factories, utilities, transport, etc.) increasingly rely on connectivity for monitoring, predictive maintenance and analytics — but that connectivity expands the attack surface and can affect safety, resilience and environmental risk. Many legacy OT systems were not designed for modern connectivity, making retroactive security improvements difficult.

This guidance helps organisations turn architectural visibility into concrete security action: apply the principles to new, revised or existing connections to reduce the attack surface, improve incident response, and protect operational safety. For practitioners working on critical services, the guidance is highly relevant to current regulatory, resilience and supply-chain concerns.

Why should I read this?

Short version: if you run, design, integrate or support OT systems and don’t fancy downtime, safety incidents or having your processes knocked about by cyber attacks — read it. It’s not dry theory: the NCSC gives usable principles and worked examples you can actually apply. Seriously, spend a few minutes on this and you’ll get clear next steps to make your connectivity decisions safer and harder for attackers to exploit.