Supervisory control and data acquisition (SCADA) is a control system architecture comprising computers, networked data communications and graphical user interfaces for high-level supervision of machines and processes. It also covers sensors and other devices, such as programmable logic controllers, also known as a distributed control system (DCS), which interface with process plant or machinery.

The operator interfaces, which enable monitoring and the issuing of process commands, such as controller setpoint changes, are handled through the SCADA computer system. The subordinated operations, e.g. the real-time control logic or controller calculations, are performed by networked modules connected to the field sensors and actuators.

The SCADA concept was developed to be a universal means of remote-access to a variety of local control modules, which could be from different manufacturers and allowing access through standard automation protocols. In practice, large SCADA systems have grown to become similar to DCSs in function, while using multiple means of interfacing with the plant. They can control large-scale processes spanning multiple sites, and work over large distances. It is one of the most commonly used types of industrial control systems.

In cryptography and computer security, a man-in-the-middle[a] (MITM) attack is a cyberattack where the attacker secretly relays and possibly alters the communications between two parties who believe that they are directly communicating with each other, as the attacker has inserted themselves between the two parties

A man-on-the-side attack is a form of active attack in computer security similar to a man-in-the-middle attack. Instead of completely controlling a network node as in a man-in-the-middle attack, the attacker only has regular access to the communication channel, which allows him to read the traffic and insert new messages, but not to modify or delete messages sent by other participants. The attacker relies on a timing advantage to make sure that the response he sends to the request of a victim arrives before the legitimate response.

Supervisory control and data acquisition (SCADA) is a control system architecture comprising computers, networked data communications and graphical user interfaces for high-level supervision of machines and processes. It also covers sensors and other devices, such as programmable logic controllers, which interface with process plant or machinery.