3.1c 2 specialized systems and ha

IoT (Internet of Things)

Networked consumer and facility devices: sensors, thermostats, doorbells, wearables, lighting and HVAC controls.

IoT security concern

Built by vendors whose expertise is not security. One exploited IoT device can give an attacker a foothold on the internal network. Segment them.

ICS (Industrial Control System)

Umbrella category for systems controlling physical industrial processes. SCADA and DCS are types of ICS.

SCADA

Supervisory Control and Data Acquisition: the ICS type for geographically dispersed assets such as pipelines, power grids, and water systems, run from a central control room.

DCS (Distributed Control System)

ICS type used within a single plant or facility rather than across dispersed sites.

PLC (Programmable Logic Controller)

The device that actually operates industrial machinery, taking commands from the control system.

HMI (Human-Machine Interface)

The operator screen used to monitor and control an industrial process.

Historian

ICS component that records and stores process data over time.

Modbus and DNP3

Legacy industrial protocols with no built-in authentication or encryption; a core reason ICS networks must be segmented.

Why ICS is hard to secure

Legacy insecure protocols, uptime is safety-critical so patching and reboots are restricted, long equipment lifecycles. Segmentation is the primary compensating control.

RTOS (Real-Time Operating System)

Deterministic OS guaranteeing a response within a fixed time window. Used in vehicles, avionics, medical, military, manufacturing.

Deterministic

Property of guaranteeing that a critical process gets resources and completes within a predictable time, e.g. anti-lock brakes.

Embedded system

Purpose-built device where hardware and software form one self-contained unit doing a single job. Traffic lights, medical monitors, digital watches.

High availability (HA)

Design that keeps a service running through component failure, automatically and without manual intervention.

Redundancy

Duplicate resources exist, but may require manual work to bring online. Not the same as high availability.

Fault tolerance

Component-level survival of a failed part within a single system, e.g. RAID arrays, dual power supplies.

Active/passive HA

One node handles traffic while a standby waits to take over on failure.

Active/active HA

All nodes handle traffic simultaneously; each must be able to carry full load alone if its partner fails.

Cost of HA

HA cascades: two firewalls implies two network paths implies two power feeds. At some point the business accepts the downtime risk instead.