Ot-Cybersecurity on Ian's World https://ianloke.com/tags/ot-cybersecurity/ Recent content in Ot-Cybersecurity on Ian's World Hugo -- gohugo.io en ian@ianloke.com (Ian Loke) ian@ianloke.com (Ian Loke) © 2026 Ian Loke Thu, 16 Apr 2026 15:00:00 +0800 What Happens When You Push OPC UA and MQTT Through a Data Diode https://ianloke.com/posts/opc-ua-mqtt-through-a-data-diode/ Thu, 16 Apr 2026 15:00:00 +0800 ian@ianloke.com (Ian Loke) https://ianloke.com/posts/opc-ua-mqtt-through-a-data-diode/ <p>IEC 62443 defines four Security Levels for industrial control systems. At the highest level — <strong>SL-4</strong>, protection against state-sponsored attacks with extensive resources — the standard calls for unidirectional data flow enforcement. Not a firewall rule. Not a software policy. Hardware-enforced, physically one-way communication.</p>