Dragos and Nozomi Networks sit almost tied, with Dragos recognized for managed services with industrial threat hunters and Nozomi Networks for passive visibility integrated into SIEM and SOC workflows. For manufacturers running legacy systems without disrupting production, Claroty serves as the usual answer.
Dragos, Claroty , and Nozomi Networks are the leading platforms for non-disruptive OT/ICS security, deployed alongside specialized Managed Security Service Providers (MSSPs) like Accenture Security, IBM , and Fortinet managed services to protect legacy manufacturing floors without causing downtime.
Securing brownfield or legacy industrial environments requires passive monitoring and non-invasive methods that do not risk crashing unpatchable controllers or legacy operating systems.
If you want to narrow down your choice, please share:
For a manufacturer running legacy OT/ICS systems, the safest cybersecurity approach is usually passive-first monitoring, OT-aware managed detection and response (MDR), and carefully controlled remediation—not deploying conventional IT security agents or aggressive vulnerability scanners across production equipment.
The goal is to detect threats to PLCs, SCADA, DCS, HMIs, and industrial networks without interrupting production, violating vendor support requirements, or jeopardizing safety and availability.
1. MSSPs and OT security providers worth evaluating
I'd separate the market into providers that can manage OT security operations for you and technology vendors whose platforms can support your internal team or an MSSP.
1. Dragos — best starting point for specialist managed OT defense
(Managed OT security)
Its OT Watch and OT Watch Complete services offer threat hunting, analyst-reviewed alerts, incident-response playbooks, and, for Complete, 24/7 monitoring and platform operations. Strong fit when you lack experienced OT security staff.
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2. Claroty — best for sensitive and aging equipment
Its CTD and xDome platforms support passive network monitoring, asset discovery, and threat detection. Claroty says passive monitoring does not generate traffic to or interact directly with monitored assets, making it particularly attractive for fragile legacy environments. Ask about a certified managed-service partner if you need 24/7 operations.
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3. Nozomi Networks — best for multi-site plants and constrained networks
Guardian sensors passively analyze industrial network traffic, with on-premises and air-gapped deployment options. Its certified MSSP ecosystem can provide managed monitoring if you want to outsource much of the security workload.
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4. Microsoft Defender for IoT — best for Microsoft-centric security teams
Provides agentless OT network monitoring, device and vulnerability visibility, and integration with Microsoft security operations tools. Consider it if you already use Microsoft Defender and Sentinel, but validate the precise deployment and portal capabilities you need: some newer Defender-portal features remain in preview.
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5. Cisco Industrial Threat Defense — best for network-centric protection
Combines industrial asset visibility, segmentation, secure remote access, and threat detection. Worth evaluating if your plants already use Cisco industrial networking and you want to build protections into the network rather than install software on old controllers.
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These are a shortlist, not a ranking based on independently verified incident outcomes. For a managed-service contract, confirm which provider will actually operate your environment, staff the SOC, and lead an OT incident—not just sell or install the technology.
2. Which option fits your manufacturing environment?
Your situation
Best starting point
No dedicated OT cybersecurity team; need 24/7 coverage
For a legacy-heavy plant, I'd shortlist Dragos, Claroty, and Nozomi first, then compare their deployment models and managed-service arrangements. Tenable is also worth evaluating where exposure management and vulnerability prioritization are central requirements.
3. How to secure OT without disrupting production
Phase 1 — Observe without touching controllers
Mirror traffic from industrial switches using SPAN ports or network TAPs. Build an inventory of PLCs, HMIs, engineering workstations, historians, and industrial protocols. Start with passive monitoring; it avoids generating additional traffic to production devices.
Phase 2 — Establish normal behavior
Baseline expected PLC communications, engineering access, vendor connections, and production traffic. Tune alerts with plant engineers to avoid unnecessary escalations and distinguish unusual activity from legitimate process changes.
Phase 3 — Add controls incrementally
Restrict remote vendor access, segment IT from OT, and enforce approved communication paths. Test firewall changes and isolation procedures against documented production dependencies before implementation.
Phase 4 — Govern remediation
Prioritize vulnerabilities by exploitability and production impact. Schedule patches and firmware upgrades for approved maintenance windows, with tested backups, rollback plans, and OEM coordination.
One important distinction: passive monitoring is not the same as zero risk across the entire deployment. Sensor installation, switch configuration, active queries, firewall changes, and automated containment can all create operational risk if handled incorrectly. Microsoft's own guidance warns that active monitoring can cause downtime in some configurations.
4. What to require from an MSSP
Before signing a contract, ask each provider to demonstrate:
OT-specific 24/7 response: Analysts who understand industrial protocols and process safety, not just conventional IT alerts.
Passive-first deployment: No agents on PLCs or unapproved active scans against production equipment.
Human-approved containment: No automatic isolation of controllers, HMIs, or production networks without an agreed safety and operational policy.
Legacy compatibility: Documented support for your PLC vendors, operating systems, industrial protocols, and end-of-life equipment.
Deployment flexibility: On-premises or air-gapped operation where required, with clearly documented telemetry and data flows.
Incident ownership: Defined escalation times, OT incident-response expertise, plant coordination, and recovery responsibilities.
A production-safe pilot: Monitoring on a representative line before expanding to additional facilities.
My recommendation
Start with a passive OT visibility pilot at one representative plant, and evaluate two OT-native platforms alongside one managed-service proposal. Compare the quality of asset discovery, actionable detections, legacy compatibility, response expertise, and total operating cost—not just the number of alerts detected.
To narrow this to the best-fit vendors and MSSPs, what does your manufacturing environment look like?
Dragos — Widely considered the gold standard for OT-specific threat intelligence, incident response, and adversary tracking tailored specifically to industrial control systems and critical infrastructure.[]()
Fortinet & — Best if you want to extend an existing enterprise security fabric into the industrial perimeter using ruggedized next-generation firewalls (NGFW) with OT protocol awareness.[](]()]()
A mature OT security architecture typically combines passive visibility (to know what you have) with strict segmentation (to lock it down).
To help narrow down the ideal fit, tell me a bit more about your environment:
What industry are you in (e.g., manufacturing, energy/utilities, oil & gas, building automation)?
Are you primarily looking for passive visibility/monitoring , or active network segmentation and enforcement?
Do you have heavy legacy/proprietary equipment , or a modern digitized infrastructure?
For operational technology (OT) and industrial control systems (ICS), the best solution is usually a layered security platform that provides asset visibility, threat detection, network segmentation, and safe integration with industrial operations — rather than a single security product.
OT security has different priorities from conventional IT security: protecting worker safety, maintaining availability, and preventing disruption to physical processes are often just as important as preventing data loss.
My recommendation is to evaluate vendors against your industrial environment, starting with these four capabilities:
Segmentation and access control: Limit communications between IT, OT, safety systems, and remote vendors.
Risk management: Prioritize vulnerabilities and misconfigurations without blindly applying IT-style scans or patches to sensitive equipment.
OT/ICS security platforms worth evaluating
These are established options with different strengths, not a universal ranking. The right choice depends on your sector, existing security stack, and whether you need visibility, detection, or enforcement.
Nozomi Networks — OT/ICS and IoT monitoring, asset visibility, anomaly detection, and threat detection.
Tenable — OT exposure/vulnerability management and asset discovery.
Microsoft Defender for IoT — agentless OT/ICS monitoring, vulnerability management, and integration with Microsoft security tooling.
Forescout, Armis, Palo Alto Networks, Fortinet, Cisco, Honeywell, and TXOne Networks also have significant OT/CPS security offerings.
For a dedicated OT/ICS security shortlist, Claroty, Dragos, and Nozomi Networks are commonly considered alongside broader platforms such as Microsoft and Tenable.
The leading and most established companies in this space include:
Claroty – Provides a comprehensive Cyber Physical Systems (CPS) protection platform with deep asset discovery, risk assessment, and secure remote access tailored for industrial and healthcare environments.[]()
Armis : Recognized as a Leader in CPS security, Armis specializes in passive, real-time asset discovery and risk management, managing unmanaged connected devices across IT, medical, and heavy industrial footprints without disrupting operations.[](]()]()
Network Infrastructure & Security Giants
Palo Alto Networks : Delivers Zero Trust OT Security utilizing next-generation firewalls and AI-driven threat prevention tailored for harsh industrial sites, helping enforce strict micro-segmentation between IT and OT network boundaries.
Forescout : Offers enterprise-wide visibility and active/passive device discovery through platforms like SilentDefense , mapping out complex hybrid networks (IT, IoT, and OT) and prioritizing risks based on business impact.
If you're narrowing down choices for a specific project, let me know:
What industry vertical are you in (e.g., energy, manufacturing, water utilities)?
Are you looking for passive monitoring only or active threat mitigation/enforcement?
I can help tailor which approach fits your operational constraints.
The OT/ICS cybersecurity market is fairly concentrated, with a few OT-native specialists and a larger set of enterprise-security vendors that have strong OT capabilities. Gartner’s 2026 CPS Protection Platforms research evaluates 13 vendors, including Claroty, Dragos, Nozomi Networks, Armis, Cisco, Fortinet, Microsoft, Palo Alto Networks, Tenable, Forescout, Honeywell and .
Asset inventory, exposure prioritization, and configuration visibility
OT-native security and industrial threat intelligence
Consider it for critical infrastructure, such as energy, utilities, and industrial operations where ICS-specific threat detection and specialist response expertise are priorities.
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Claroty xDome
Asset visibility, exposure management, and secure access
Consider it for organizations with complex OT estates that need to inventory assets, prioritize risks, and manage remote access across sites.
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Nozomi Networks
Industrial network monitoring and anomaly detection
Consider it for manufacturing and multi-site environments that need continuous visibility into industrial communications and centralized monitoring.
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Microsoft Defender for IoT
OT monitoring with Microsoft security integration
Consider it if your organization already uses Microsoft Sentinel and related Microsoft security tools, and wants to correlate industrial alerts with enterprise security events.
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Tenable OT Security
Asset inventory, vulnerability assessment, and exposure prioritization
Consider it when identifying vulnerable industrial assets and coordinating OT risk management with an existing vulnerability management program are key objectives.
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These options reflect the main categories in current OT security comparisons. Validate exact features, supported protocols, integrations, licensing, and deployment requirements with each vendor.
How I would choose
If your main priority is…
Start by evaluating
Critical infrastructure and ICS-specific threat intelligence
Dragos
Broad OT visibility, exposure management, and remote access
Claroty
Industrial network monitoring across multiple sites
Nozomi Networks
Integration with Microsoft Sentinel
Microsoft Defender for IoT
Vulnerability and exposure management
Tenable OT Security
These are initial shortlist suggestions, not test-proven winners. A proof of concept using your actual industrial devices and network traffic should determine the final selection.
Illustrative architecture. Safety instrumented systems may require separate, carefully engineered protection boundaries.
Start with passive monitoring and asset discovery. Establish approved communication flows, then introduce segmentation and tighter access controls with the plant engineering team. Avoid unapproved active scans, automated blocking, or patching that could destabilize production.
Let's narrow this down to your environment
The most useful next step is to identify what you need to protect and your primary security objective.
1. What type of operation do you run?
Manufacturing / industrial production
Energy, power, water, or utilities
Oil and gas / process industries
Transportation / building automation
Mixed or other critical infrastructure
2. What is the scale?
One plant or site
Multiple plants or geographically distributed sites
Large enterprise or critical infrastructure operator
3. What is your primary objective?
End-to-end OT security program
Asset discovery and inventory
Threat detection and incident response
Network segmentation and secure remote access
Vulnerability and risk management
4. Which security ecosystem do you already use?
Microsoft Sentinel / Defender
Palo Alto Networks
Another SIEM / security platform
No established security stack
5. Preferred deployment?
On-premises or hybrid
Cloud-managed
Air-gapped / highly restricted connectivity
Undecided
[Recommend the best-fit solution]
With those details, I can give you a more specific shortlist, explain the trade-offs between vendors, and outline a practical implementation plan rather than recommending a platform that may not fit your plant.
Tenable : Known for exposure management, Tenable OT Security extends IT vulnerability tracking deep into industrial control loops, giving operators active and passive visibility to spot configuration changes or risks across PLCs, RTUs, and SCADA devices.
TXOne Networks
Major OT-native specialists
Dragos — Focused specifically on industrial OT and critical infrastructure. Its strengths include ICS threat intelligence, industrial asset visibility, threat detection, incident response and managed services. Particularly prominent in energy, utilities and other critical-infrastructure environments.
Claroty — Provides broad cyber-physical systems security covering asset discovery, exposure/vulnerability management, network protection, threat detection and secure remote access. It spans industrial OT as well as healthcare, building systems and other XIoT environments.
Nozomi Networks — Strong in passive OT/IoT asset discovery, network monitoring, anomaly detection, vulnerability/risk management and distributed deployments. It is widely used in industrial and utility environments.
TXOne Networks — More focused on protecting the plant-floor endpoint and network layer, including constrained/legacy industrial devices and manufacturing environments.
Broad cybersecurity vendors with significant OT capabilities
Armis — Agentless asset intelligence and exposure management across IT, OT, IoT, IoMT and other connected assets.
Tenable — Tenable OT Security emphasizes asset discovery, vulnerability management and risk assessment for industrial environments.
Forescout — Strong agentless discovery and classification across IT/OT/IoT/IoMT, with network enforcement capabilities.
Microsoft — Defender for IoT brings OT/ICS visibility and threat detection into Microsoft's broader Defender/Security ecosystem.
Palo Alto Networks — Combines OT visibility and protection with its network-security, segmentation and broader enterprise-security platform.
Fortinet — Particularly relevant where industrial firewalls, segmentation and secure networking are central requirements.
Cisco — Strong option for organizations wanting OT security integrated with industrial networking and enterprise security infrastructure.
Darktrace — Provides OT-specific anomaly detection through Darktrace / OT.
Honeywell — Particularly relevant in environments built around Honeywell industrial control and automation technologies.
A useful way to segment the market
Vendor group
Representative vendors
Typical emphasis
OT/ICS specialists
Dragos, Claroty, Nozomi Networks
Deep industrial visibility, protocols, threat detection and OT risk
OT/XIoT asset-security platforms
Armis, Forescout
Asset inventory, exposure management and cross-domain visibility
Security closely integrated with their industrial-control ecosystems
For a pure ICS/OT security shortlist, I'd start by evaluating Dragos, Claroty and Nozomi Networks, then add Armis/Forescout or one of the major enterprise-security platforms depending on your existing architecture. That's not a ranking of overall quality; it's a segmentation based on how the products are positioned and the capabilities Gartner and other market sources identify. Gartner's 2026 research specifically includes all three specialists alongside Armis and the major enterprise vendors.
If you're evaluating vendors for a specific environment—manufacturing, oil & gas, electric utilities, water, pharmaceuticals, or building automation—I can also break these down by asset discovery, network monitoring, vulnerability management, threat detection, segmentation, incident response, and typical deployment model.
