Operational Technology (OT) systems, such as ICS, SCADA, and manufacturing networks, are unique in their sensitivity and risk. Monitoring in OT environments must prioritize reliability, integrity, and fail-safe design. This checklist offers clear, actionable steps across the lifecycle of OT monitoring.

1. Risk & readiness assessment

Key tasks:

• Pinpoint all safety-critical control loops and network interfaces, focusing on standard OT protocols such as PROFINET, Modbus/TCP, and IEC 104.
  
  
• Identify key operational assets whose uninterrupted functionality is essential to process safety and compliance.
  
  
• Assess switch architecture to guarantee redundancy using protocols like PRP (Parallel Redundancy Protocol) and HSR (High-availability Seamless Redundancy), minimizing the risk of single points of failure.
  
  
• Verify DIN-rail mounting compatibility and confirm adequate industrial-grade power provisioning to support device operation across extended temperature ranges (-40 °C to +70 °C).
  
  
• Secure necessary authorizations for any physical interventions in live environments, coordinate maintenance windows, and plan for hot-cut transitions or scheduled downtime as dictated by operational criticality.

Risk Matrix: Monitoring Failures in OT Environments

OT networks prioritize reliability, safety, and regulatory compliance. Below is a simple risk matrix showing how specific monitoring failures can impact critical dimensions in an industrial environment:

2. Installation & commissioning

Key tasks:

• Utilize passive TAPs at critical network segments to ensure monitoring access without introducing active points of failure, thereby guaranteeing complete traffic visibility and supporting fail-safe operations even in extreme fault scenarios.

• Deploy active TAPs equipped with fail-open relay mechanisms when inline bypass capability is required. This ensures that traffic continues to flow without interruption during device outages or maintenance and aligns with high-availability policies standard in OT environments.

• Rigorously validate monitor port isolation to guarantee unidirectional data flow; confirm that monitoring devices are incapable of injecting any packets into the operational network, thereby eliminating risks of unintended system interference or unauthorized access.

• Use standardized labeling for all cables, incorporating P&ID (Piping & Instrumentation Diagram) tags for traceability. This facilitates swift troubleshooting, ensures correct installation, and streamlines maintenance workflows in complex cabinet or rack deployments.

• Configure packet broker filters with precision, allowing only protocol traffic essential for analysis (e.g., filter by EtherNet/IP, Modbus/TCP, IEC 104) to ensure performance efficiency, data privacy, and compliance with traffic segregation requirements fundamental to regulated OT environments.

3. Operational phase

Key tasks:

• Continuously monitor packet broker rules for network anomalies such as broadcast storms, beaconing events, traffic floods, and abnormal jitter patterns. This proactive analysis allows for early detection of operational threats, reduces network downtime, and protects the integrity of time-sensitive industrial communications.
  
  
• Leverage IOTA dashboards to systematically track packet retransmissions, latency variations, and throughput trends, providing network engineers with actionable insights into network health and recurring issues. Historical trend analysis helps differentiate between normal operational baselines and emerging performance degradations, ensuring optimal process reliability.
  
  
• Automatically export full packet captures (PCAPs) at specified intervals or per event to Security Operations Centers (SOCs) or long-term historians. This workflow supports comprehensive forensic investigations, incident response, and data retention requirements relevant to regulated industrial environments.
  
  
• Implement a strict firmware management process by allowing firmware updates on PLCs only after thorough testing and validation in a dedicated testbed environment. This step reduces the risk of vulnerabilities, ensures compatibility with deployed monitoring tools, and complies with both operational and security standards.
  
  

4. Compliance & incident response

Key tasks:

• Maintain a “golden baseline” packet capture for each programmable logic controller (PLC), creating a comprehensive reference of normal network and device behavior. This baseline should be updated following significant firmware upgrades, configuration changes, or network modifications to ensure ongoing accuracy for anomaly detection, diagnostics, and proof-of-compliance during audits. Storing this securely allows fast comparison during incident triage and supports root cause analysis when operational deviations occur.

• Ensure a full cryptographic chain-of-custody by generating cryptographic hashes for every captured packet file and applying digital signatures from authorized operators. Each step of acquisition, storage, transfer, and access should be tracked, providing tamper-evidence, incontrovertible file integrity, and compliance with legal and regulatory evidentiary requirements such as IEC 62443 and NIS2.

• Document all monitoring TAP installation points and retrieval points comprehensively in a Computerized Maintenance Management System (CMMS), and ensure every change, maintenance activity, or relocation is registered in Management of Change (MOC) logs. This facilitates transparent audit trails, streamlined maintenance, rapid impact assessment for upgrades, and compliance with internal governance and external inspections.

• Run regular failover drills by disconnecting each TAP from in-line network positions and verifying immediate, uninterrupted line continuity for process-critical links. This exercise validates redundancy mechanisms and fail-open relay functionality and ensures operators and engineers are fully trained in real-world recovery procedures, minimizing response times and limiting operational disruption during unplanned outages.

• Enforce strong security for all remote access, including for vendors, maintenance personnel, and internal engineering staff, by mandating encrypted VPN connections and multi-factor authentication (MFA). Implement robust session logging, access schedules, and strict account management procedures to reduce the risk of unauthorized access, align with cybersecurity best practices, and immediately detect or block suspicious attempts in accordance with industrial security standards.

OT monitoring isn’t just about visibility but safety, compliance, and trust. This checklist ensures your critical systems are protected with industrial-grade visibility, backed by forensic resilience and operational continuity.