PCN PEP key terms

A reference hierarchy that arranges industrial systems into levels from physical process (Level 0) up through basic control, supervisory control, site operations, and enterprise networks, used to describe where devices sit and where boundaries belong.

A segmentation approach from IEC 62443 in which assets sharing security requirements are grouped into zones, and the communication paths permitted between zones are defined as conduits with documented controls.

A controlled communication path between two security zones that specifies which protocols, directions, and endpoints are allowed, plus the protective measures applied along that path.

A buffer network placed between operational technology and enterprise IT where shared services such as historians, patch repositories, and jump hosts live, so no direct traffic crosses between the two environments.

A hardware device that enforces one-way traffic flow, typically allowing process data to leave an operational network while physically preventing any signal from returning into it.

A device or appliance that permits data transfer in only one direction across a network boundary, often paired with protocol breaks and content checks to protect the receiving side.

A hardened, monitored intermediary server that administrators must connect through before reaching operational assets, centralizing authentication, logging, and session recording.

An industrial protocol that carries Modbus function codes over TCP/IP, typically on port 502, with no built-in authentication or encryption, so access control depends entirely on network design.

A master-outstation protocol widely used in electric and water utilities that supports time-stamped events, unsolicited reporting, and optional secure authentication extensions for critical commands.

The field device in a DNP3 system that collects data from equipment and responds to requests from a master station, reporting events and accepting control commands.

A numeric field in Modbus and similar protocols that tells the receiving device what operation to perform, such as reading coils or writing a single register.

A protocol operation that changes a value in a controller's holding registers, which in process environments can alter setpoints or outputs and therefore warrants strict monitoring and authorization.

A platform-independent industrial interoperability standard that provides built-in authentication, encryption, and certificate-based trust for exchanging structured data between systems.

An Ethernet-based industrial protocol used mainly for controller-to-device communication in manufacturing, supporting real-time cyclic data exchange and diagnostics over standard or specialized network hardware.

An industrial Ethernet protocol that carries Common Industrial Protocol messages over TCP and UDP, used for both configuration traffic and real-time I/O exchange between controllers and devices.

Ethernet adapted for plant environments through ruggedized hardware, deterministic behavior options, and industrial protocols, distinguishing it from office networking even though it shares the same standards base.

A rugged industrial computer that runs a stored control program to read inputs and drive outputs in real time, forming the core of most process and manufacturing control loops.

A field device that gathers measurements and executes commands at a remote site, commonly reporting to a supervisory system over telemetry links in utility and pipeline environments.

The layer of a control system that provides operators with visibility and command capability over field controllers, typically through human-machine interfaces and data acquisition servers.

The target value a control loop drives toward, such as a temperature or pressure threshold, whose unauthorized change can directly affect product quality or process safety.

A feedback mechanism that compares a measured process value to a setpoint and adjusts an output to reduce the difference, forming the basic unit of automated process regulation.

An independent protective system that monitors for hazardous conditions and drives the process to a safe state, designed and maintained to a defined safety integrity level separate from basic control.

A graded measure of the risk reduction a safety function provides, expressed as target failure probability ranges and used to specify how reliable protective equipment must be.

Analysis of packet payloads beyond headers to identify protocols, commands, and anomalies, allowing industrial firewalls and monitors to enforce rules on operations rather than just addresses and ports.

A network security device designed to understand industrial protocols and tolerate plant conditions, enforcing rules that permit only approved commands and directions between zones.

A periodic examination of configured permit and deny rules to confirm each remains justified, correctly scoped, and aligned with documented conduits, removing stale or overly broad entries.

Observing network traffic without sending packets or interacting with devices, used to build asset inventories and detect anomalies with minimal risk to fragile control equipment.

Probing devices directly to discover open ports and services, which yields detail but can disrupt sensitive controllers and therefore requires scheduling, approval, and safe tool settings.

A passive hardware device inserted on a link that copies traffic to a monitoring port, providing complete visibility without altering or delaying the original data flow.

A switch feature that mirrors traffic from selected ports or VLANs to a monitoring destination, useful for visibility but prone to dropping packets under heavy load.

A maintained record of hardware, software, firmware versions, network addresses, and owners for devices in scope, serving as the foundation for patching, monitoring, and risk decisions.

A documented, approved set of device and system settings used as the reference for detecting unauthorized change and for restoring systems to a known good state.

A controlled process for requesting, reviewing, testing, approving, and recording modifications to operational systems, ensuring changes are intentional and reversible.

An alternative safeguard applied when a preferred control cannot be implemented, such as isolating an unpatchable controller behind strict rules and enhanced monitoring.

Layering independent preventive, detective, and corrective controls so that failure of any single measure does not expose the process to unmitigated harm.

Granting users and systems only the access needed for their assigned tasks, limiting the blast radius of credential theft or error in operational environments.

Tools and processes that vault, broker, and record high-risk accounts and sessions, reducing standing administrative rights on control systems and engineering workstations.

Capturing keystrokes and screen activity during administrative connections so that actions on critical systems can be reviewed, audited, and investigated after an incident.

A structured evaluation of threats, vulnerabilities, and consequences against defined assets to estimate risk and prioritize which safeguards or design changes to fund first.

The point at which a vendor stops issuing patches or fixes for a product, leaving known flaws permanently unaddressed and requiring isolation or replacement planning.

A documented set of roles, escalation paths, communication steps, and containment procedures tailored to operational technology, including provisions for safe process shutdown decisions.

Actions taken to stop the spread of an intrusion, which in process environments must balance network isolation against the risk of disrupting live control and safety functions.