Best 20 Network Monitoring Tools for OT Cybersecurity

The Imperative of Visibility in a Converged World

The industrial landscape is undergoing a revolutionary transformation driven by IT/OT Convergence and the massive adoption of Industrial IoT (IIoT) devices. Operational Technology (OT) networks-which govern critical infrastructure like power grids, manufacturing plants, and water treatment facilities-were historically “air-gapped” and designed for reliability and safety over security.

However, modern business demands for efficiency, remote operations, and data analytics have blurred this once-clear boundary. Programmable Logic Controllers (PLCs), Supervisory Control and Data Acquisition (SCADA) systems, and Distributed Control Systems (DCS) are now frequently connected to the corporate IT network and, by extension, the public internet. This connectivity, while beneficial for productivity, has exponentially expanded the attack surface of critical infrastructure.

The stakes in the OT world are profoundly higher than in a typical IT environment. A cyber-attack in an OT network doesn’t just result in data loss or financial fraud; it can lead to physical safety incidents, massive environmental damage, or prolonged, costly production shutdowns. The notorious Stuxnet attack demonstrated the potential for cyber means to cause physical destruction, while recent ransomware incidents like Colonial Pipeline highlighted the critical link between IT breaches and OT operational disruption.

Why Traditional IT Tools Fail in OT/ICS Environments

The core challenge for security teams lies in a fundamental difference:

• OT Priority: Safety and Availability (The process must run). Systems often run on legacy, proprietary hardware and use unique industrial protocols (like Modbus/TCP, EtherNet/IP, Profinet, etc.) that cannot tolerate active scanning or be patched easily.
• IT Priority: Confidentiality and Integrity (Data must be secure). Systems are designed for frequent patching and use standard protocols (TCP/IP, HTTP, DNS) that respond well to active monitoring.

Traditional IT Network Monitoring Tools (NMTs) that rely on active probing (like Nmap or SNMP polling) can actually destabilize and crash sensitive industrial control devices. Therefore, specialized OT Network Monitoring is not an option-it is a mandatory foundation for modern industrial cybersecurity.

The single most critical step in securing an OT environment is achieving Deep Network Visibility and Asset Inventory. You cannot protect what you cannot see. OT-specific Network Monitoring Tools are built to provide this visibility through passive monitoring-listening to network traffic without actively interacting with the devices-to decode industrial protocols and establish a secure baseline of normal industrial operations.

The Core Functionality: What an OT NMT Must Do

The best OT Network Monitoring Tools are more than just packet analyzers. They are sophisticated platforms that fulfill several crucial cybersecurity and operational requirements in one consolidated view.

1. Granular Asset Discovery and Inventory

The primary function is to map the entire industrial network. A high-quality tool should provide:

• Deep Contextual Data: Not just an IP and MAC address, but the device vendor, model, firmware version, serial number, location (e.g., PLC-01 in Refinery Unit 3), backplane configuration, and installed modules.
• Passive-Only Discovery: Safely identifying every asset without impacting operations by leveraging techniques like Deep Packet Inspection (DPI) to analyze industrial protocols.
• Continuous Monitoring: Maintaining a real-time, dynamic inventory that automatically updates when a new device connects or a firmware version changes, which is critical for change management and compliance.

2. Behavioral Baseline and Anomaly Detection (NDR for OT)

This is the heart of threat detection in a stable, predictable industrial environment:

• Baselinng: The tool must learn the “normal” operational behavior-which controllers talk to which HMIs, which commands are used, the typical frequency of communication, and even the normal value ranges for process variables.
• Protocol Violation: Detecting communications that violate the rules of the industrial protocol (e.g., an unauthorized write command).
• Policy Violation: Alerting on actions that violate pre-defined security policies (e.g., a laptop connecting to the PLC network segment).
• Statistical Anomaly: Flagging deviations from the learned baseline (e.g., a PLC suddenly communicating with a new, external IP address, or an unprecedented volume of Modbus traffic).

3. Vulnerability and Risk Management

By combining asset inventory with proprietary or third-party threat intelligence, the tool can:

• Identify Vulnerabilities: Map discovered firmware versions against known Common Vulnerabilities and Exposures (CVEs) relevant to ICS assets.
• Prioritize Risk: Assign a risk score based not only on the CVE severity but also on the asset’s criticality (e.g., a vulnerability on a primary safety PLC is more critical than on a historian server).
• Manage Patching: Provide risk-based guidance, often without requiring invasive network scans.

4. Protocol-Specific Threat Signatures

Beyond general network threats, the tool must recognize attacks targeting the logic of industrial processes. This includes signatures for:

• Exploits in common OT protocols (e.g., a known exploit in a specific version of OPC UA).
• Malware families specifically targeting ICS (e.g., Industroyer, Triton, Havex).
• Unauthorized changes to PLC logic or ladder-logic program uploads/downloads.

The Best 20 Network Monitoring Tools for OT Cybersecurity

The industrial security market has matured, moving beyond basic network visibility to comprehensive platforms that offer deep analytics and response capabilities. The following tools represent the current leaders, categorized by their primary focus and deployment model.

Category 1: Dedicated, Leader-Tier OT Security Platforms (OT/ICS NDR)

These platforms are purpose-built for OT environments, offering the deepest visibility, threat intelligence, and most mature features. They are the backbone of a modern industrial security program.

1. Dragos Platform:
   • The Edge: Renowned for its unparalleled, human-driven industrial threat intelligence. Dragos’s team of ICS-specific threat hunters feeds real-time intelligence into the platform, making it exceptional at detecting sophisticated, niche attacks (e.g., identifying a threat based on a specific custom function code in a proprietary protocol).
   • Key Feature: The Dragos Threat Operations Center (TOC) provides managed services and hunting playbooks directly within the tool.
2. Nozomi Networks Guardian:
   • The Edge: A market veteran known for its comprehensive, deep asset discovery, vulnerability assessment, and extensive protocol support. It is highly scalable across large, geographically dispersed OT environments.
   • Key Feature: Strong integration with IT security tools (SIEM/SOAR), providing a unified view of the converged IT/OT attack surface. Highly rated for ease of deployment.
3. Claroty Platform (Continuous Threat Detection – CTD):
   • The Edge: Focuses heavily on the full lifecycle of industrial asset protection, from discovery and vulnerability assessment to secure remote access (SRA). Offers an exceptional combination of passive monitoring and non-intrusive queries to gather deep asset details.
   • Key Feature: Strongest focus on Secure Remote Access (SRA), critical for managing vendor and third-party access securely, and robust integration into the overall Claroty security suite.
4. Tenable.ot (formerly Indegy):
   • The Edge: Leverages Tenable’s extensive vulnerability management expertise and integrates it seamlessly with OT-specific protocol monitoring. It is highly effective at combining passive network monitoring with selective, safe active querying to validate asset details.
   • Key Feature: Excellent at integrating vulnerability data from the OT network into the broader enterprise-wide Tenable risk management platform.
5. Cisco Cyber Vision:
   • The Edge: Integrates industrial security directly into the network infrastructure by embedding sensors within Cisco’s industrial routers, switches, and firewalls. This reduces the hardware footprint and leverages existing network investments.
   • Key Feature: Deep integration with the Cisco Security ecosystem (e.g., Cisco Identity Services Engine – ISE) to enforce dynamic segmentation and access control based on asset context.

Category 2: AI-Driven & Converged Security Platforms (NDR/XDR)

These tools utilize advanced Machine Learning (ML) and Artificial Intelligence (AI) to establish dynamic baselines and excel in managing the converged IT/OT/IoT ecosystem.

6. Darktrace/OT:
   • The Edge: Uses unsupervised machine learning (AI) to build a unique “sense of self” for every device and network segment in the OT environment. It’s highly effective at spotting never-before-seen, zero-day anomalies that deviate from the normal pattern of life.
   • Key Feature: Self-Learning AI for behavioral modeling, which drastically reduces reliance on pre-defined rules or signatures, making it effective against novel attacks.
7. Armis Centrix for OT/IoT Security:
   • The Edge: Specializes in identifying and securing every connected asset-managed or unmanaged-across the entire attack surface (IT, OT, IoT, IIoT, IoMT). It uses agentless technology for passive collection.
   • Key Feature: Exceptional asset inventory and discovery capabilities, particularly strong in managing the burgeoning IoT and IIoT devices now prevalent in industrial environments.
8. Fortinet FortiGuard Industrial Security Service:
   • The Edge: Part of the broader Fortinet Security Fabric, offering specialized OT threat intelligence and monitoring for over 70 OT protocols. It allows for consistent security policy enforcement across both the IT and OT domains.
   • Key Feature: Unified management and enforcement across the entire IT-OT security infrastructure, leveraging Fortinet’s high-performance firewalls and threat intelligence.

Category 3: Vendor-Specific & OEM Solutions

These tools are often bundled with or designed by the major industrial automation vendors, offering native integration and deep knowledge of their own equipment.

9. Honeywell Forge Cybersecurity:
   • The Edge: Leverages Honeywell’s deep domain expertise as an industrial vendor. Its solutions are deeply integrated with its own DCS and SCADA systems, offering visibility into the operational process layer that others may miss.
   • Key Feature: A holistic approach that often includes a mix of software, professional services, and a deep understanding of process control and functional safety.
10. Schneider Electric EcoStruxure Secure Connect Advisor:
    • The Edge: Focuses on providing a secure, monitored remote access solution essential for maintenance and vendor support. It includes network monitoring capabilities to ensure compliance and detect unauthorized changes during remote sessions.
    • Key Feature: Strong emphasis on controlled, auditable, and secure remote connectivity-a major OT security weak point.

Category 4: Enterprise-Grade Converged Monitoring and Analytics

These IT-centric platforms have adapted to support OT environments through specialized industrial protocol plugins and integration with the dedicated OT platforms listed above. They are ideal for organizations aiming for a single pane of glass in their Security Operations Center (SOC).

11. Splunk for Industrial Cybersecurity:
    • The Edge: While a log and event management platform (SIEM), Splunk has developed specialized apps and content packs to ingest, normalize, and analyze data from OT security tools (like Nozomi and Dragos), as well as ICS device logs.
    • Key Feature: Unmatched correlation and big-data analytics power. It allows security teams to correlate events across the IT and OT boundary to identify complete attack chains.
12. IBM Security QRadar (with OT Add-ons):
    • The Edge: Similar to Splunk, QRadar is a powerful SIEM that offers specialized add-ons and integrations for OT environments, supporting industrial protocols and ICS-specific use cases.
    • Key Feature: Robust threat intelligence feed (X-Force) and strong SOAR capabilities for automating incident response processes across IT/OT.
13. Microsoft Defender for IoT (formerly CyberX):
    • The Edge: A cloud-native solution that offers passive OT/ICS network monitoring integrated directly into the Microsoft security ecosystem (Azure, Sentinel). Ideal for organizations heavily invested in Microsoft cloud services.
    • Key Feature: Seamless integration with Azure Sentinel (Cloud SIEM) and the broader Microsoft XDR suite, providing a unified management experience for IT, IoT, and OT.
14. SolarWinds Network Performance Monitor (NPM) (with OT extensions):
    • The Edge: Traditionally a strong IT NMT, SolarWinds offers modular extensions that can accommodate some OT protocols (like Modbus/TCP) and provide basic availability and performance monitoring for industrial networks.
    • Key Feature: Excellent for performance troubleshooting, availability monitoring, and visualizing network topology in converged environments.
15. Paessler PRTG Network Monitor (with industrial sensors):
    • The Edge: A flexible, sensor-based monitoring solution that has developed specialized sensors for common industrial protocols and equipment (e.g., Modbus, OPC).
    • Key Feature: Highly customizable, cost-effective for smaller OT environments or isolated segments, and excels at uptime and basic health checks.

Category 5: Specialized & Open Source Tools (The Deep Dive Toolkit)

These tools are essential for incident response, threat hunting, and environments where a full-scale commercial platform may not be feasible. They require a high level of expertise to configure and interpret.

16. Wireshark (Protocol Analyzer):
    • The Edge: The industry standard for deep packet inspection. It can decode numerous industrial protocols (with the right dissectors) and is indispensable for incident response forensics and understanding specific network issues.
    • Key Feature: Raw, unfiltered, deep-level visibility into every packet. It’s the ultimate forensic tool, but requires expert knowledge to use effectively for continuous monitoring.
17. Security Onion (NDR/IDS Suite):
    • The Edge: A free, open-source Linux distribution for intrusion detection, network security monitoring, and log management. It bundles tools like Suricata and Zeek, which can be configured with ICS-specific signatures and scripts.
    • Key Feature: A powerful, cost-effective suite for threat hunting and network forensics, leveraging the power of open-source security tools.
18. Zeek (formerly Bro) (Network Security Monitor):
    • The Edge: Not a traditional IDS but a network behavior monitoring system. It creates detailed logs and transactional records of all network activity, making it excellent for post-incident analysis and establishing complex baseline rules.
    • Key Feature: Generates high-level, semantic logs from raw traffic, making data analysis much faster than sifting through raw packets. Supports custom scripting for OT protocols.
19. Snort/Suricata (Intrusion Detection Systems):
    • The Edge: High-performance, signature-based IDS engines. They can be loaded with ICS-specific signature sets (often available publicly or through commercial threat feeds) to detect known malware and attack patterns in real-time.
    • Key Feature: Fast, real-time alerting based on known threat patterns, ideal for perimeter or segmentation boundary monitoring.
20. Optigo Visual Networks (for Building Automation/BAS):
    • The Edge: A highly specialized platform for Building Automation Systems (BAS), which often use protocols like BACnet and Modbus over IP. BAS/BMS are increasingly recognized as a major OT threat vector.
    • Key Feature: Uniquely tailored for the challenges and protocols specific to building management and smart facilities, which is a growing, often overlooked segment of OT security.

Choosing Your Industrial Sentinel: The Selection Strategy

Selecting the right tool for an OT environment is a critical decision that must align with the operational reality of your plant, not just your security budget.

1. Protocol Prowess is Non-Negotiable

The tool must natively and passively support the industrial protocols in your specific environment (e.g., Modbus, EtherNet/IP, DNP3, OPC UA, PROFINET, and proprietary variants). A tool that can only decode the standard IP layer is essentially blind in the control network.

2. Deployment Model: Passive is Paramount

Prioritize solutions that are 100% passive for asset discovery and continuous monitoring. They should use Switched Port Analyzer (SPAN) ports, Test Access Points (TAPs), or network visibility fabrics (like Gigamon) to non-intrusively analyze traffic. Any tool proposing routine, active scanning for asset discovery or vulnerability assessment should be treated with extreme caution in a live production environment.

3. Integration with the SOC

The best OT NMTs act as a specialized sensor for the larger enterprise security ecosystem. They must have robust, bi-directional integration with your SIEM/SOAR platform (Splunk, QRadar, Sentinel) to centralize alerts and automate response workflows. Alert fatigue is a major problem; the tool should provide context-rich, prioritized alerts, not just noise.

4. Operational Technology Context

The most valuable tools can map security alerts to the physical process. A good tool doesn’t just say “IP A communicated with IP B”; it says, “Unauthorized modification command from a vendor’s laptop to PLC-04 controlling the high-pressure valve in the cracking unit.” This operational context transforms a security alert into an actionable incident for both the security and operations teams.

5. Threat Intelligence and Research

Choose a vendor that commits significant resources to industrial-specific threat intelligence and research (like Dragos, Nozomi, Claroty). The OT threat landscape is specialized, and generic IT threat feeds are often irrelevant. You need expertise that understands the motivation and TTPs (Tactics, Techniques, and Procedures) of adversaries targeting ICS.

The Future: Deep Observability and OT-XDR

The trend in 2025 and beyond is moving toward Deep Observability and OT-XDR (Extended Detection and Response).

• Deep Observability: This means moving beyond network traffic to ingesting data from other sources like physical sensors, control loop metrics, and even controller memory. The future platform won’t just detect a malicious network packet-it will flag when a controller’s temperature reading changes unexpectedly in a way that suggests tampering with its logic, even if no packet was involved.
• OT-XDR: The goal is to unify the data streams from the dedicated OT monitoring platforms (Category 1) with IT/IoT visibility tools (Category 2 & 3) and endpoint security solutions (EDR) to create a single, automated, and context-rich response playbook that can span the entire converged environment.

By implementing one of these leading OT Network Monitoring Tools, industrial organizations are not just buying software; they are investing in an Industrial Sentinel-a dedicated, non-intrusive defender that provides the critical visibility required to maintain safety, ensure uptime, and successfully navigate the escalating threats of the converged IT/OT world.