Asset
Any physical or software component used in an industrial control system.
Industrial Control System (ICS)
An automation system that monitors and controls industrial or manufacturing processes.
Building Control System (BCS)
A type of ICS that automates building functions like HVAC, lighting, and access control.
Industrial Protocols
Protocols used for ICS communications, often originally serial and now carried over TCP or UDP (for example, Modbus/TCP).
Routable Network
A network that uses IP-based protocols (such as TCP/IP or UDP/IP) so traffic can be routed between segments.
Business Network
The IT network that supports business systems like email, file sharing, and enterprise applications.
Critical Asset
A facility, system, or equipment essential to safe and reliable operation (such as key substations or control centers).
Critical Cyber Asset
A networked device that supports a Critical Asset and, if compromised, could affect operations (often using routable protocols or dial-up access).
Bulk Electric System (BES)
The large-scale power generation and transmission system that delivers electricity over a wide area.
Zone
A group of assets with similar function or security needs, treated as a single protected area.
Conduit
A controlled communication path between zones that enforces who and what can access resources.
Electronic Security Perimeter (ESP)
The logical boundary around critical cyber assets where network access is tightly controlled.
Demilitarized Zone (DMZ)
A buffer network that exposes limited services to less-trusted networks while protecting internal control networks.
Firewall
A device or software that filters network traffic based on rules, such as IP address, port, or protocol.
Deep Packet Inspection (DPI)
Analysis of the actual contents of network traffic to understand protocols and detect suspicious behavior.
Intrusion Detection System (IDS)
A system that monitors activity and alerts on suspected attacks but does not block traffic.
Intrusion Prevention System (IPS)
A system that detects suspicious activity and can automatically block or modify traffic.
Unified Threat Management (UTM)
An appliance or application that combines multiple security functions, such as firewall, DPI, and intrusion prevention, into one platform.