(HMI) Sometimes called the (Man Machine Interface) MMI or (Human Computer Interface) HCI. These are nodes at which control engineers monitor their plants, factories, pipelines, and field devices. Often found in control rooms, but sometimes dispersed across the plant oor. These are often running a well known operating system and any internet reachability is of particular concern as these nodes are in control of field or plant devices. Anecdotally, changing a display on an HMI can cause an operator to perform a detrimental safety critical action under false pretences, in a similar manner to Phishing attacks on banking customers today. [Systems]