OT and IoT security is the protection of the machines, sensors and cameras that run a factory or a plant. OT means operational technology: the equipment that controls physical things, such as a pump or a conveyor. IoT means the internet of things: ordinary devices, such as cameras and sensors, that are connected to a network.
These devices need their own protection for three reasons. First, there are far more of them than anyone has listed. A plant can have thousands of devices on its network, and the security team may not know about many of them. Second, they are old and cannot be updated easily. A PLC may run the same software for fifteen years. Third, they cannot be switched off to install a fix, because the plant would stop.
OT security software therefore does two things. First, it discovers every device on the plant network by listening to the traffic. It records each device's type, maker and address. Second, it controls what each device may reach, using network access control and micro-segmentation, which splits one network into small zones.
OT security differs from ordinary office IT security in what it must protect first. An office network protects information, and a computer can be restarted to install a fix. A plant network protects safety and continuous running. Without protection, a wrong command to a valve or a motor can spill a chemical, damage a machine or hurt a worker, and the plant loses every hour that it stands still. So the plant would rather keep an old, unpatched controller running behind strict network limits than restart it.
Consider a plant with a thermal camera on the packing line. The software sees that the camera sends data only to the plant's own server. One day the camera starts sending data to an address outside the country. The software raises an alert to the plant's SIEM, the system that collects all security alerts, and blocks the camera from the network.
The buyers are plants in power, oil and gas, chemicals, metals and manufacturing. The purchase is usually made by the plant's engineering head together with the company's security operations team, since the two groups have to agree on what may be changed on a running plant.
The same software protects distributed control systems and SCADA screens. It also checks the connections that equipment makers use to repair machines from far away, with remote desktop software. Each such connection is a way into the plant, so the software records who connected and what they changed. Plants with their own private 5G network and edge computers need to protect those as well. For ships, the same idea is applied in maritime cyber security.