Industrial IDS/IPS protects OT/ICS environments by detecting suspicious activity on industrial networks (IDS) and, in limited cases, blocking it (IPS). Most industrial deployments start with passive monitoring (OT NDR/IDS) using SPAN/TAP traffic copies to avoid disrupting operations. Inline IPS is used selectively at well-defined choke points—like remote access, inter-zone conduits, and the OT DMZ—because blocking the wrong traffic can impact safety and uptime. Claroty, Nozomi Networks, and Dragos all focus on OT visibility and threat detection, but they differ most in operational workflows, deployment flexibility, ecosystem integrations, and how they present risk context and incident response for industrial teams.
What “industrial IDS/IPS” means in OT/ICS
Industrial networks are not just “IT with different devices.” In OT/ICS you’re dealing with:
- Industrial protocols (e.g., Modbus/TCP, DNP3, EtherNet/IP, PROFINET, IEC 104, OPC UA)
- Specialized endpoints (PLCs, RTUs, IEDs, safety controllers, HMIs, historians, engineering workstations)
- Deterministic traffic (cyclic polling, stable peer-to-peer communications, strict timing)
- Higher consequence of mistakes (availability and safety often outrank confidentiality)
So industrial IDS/IPS typically means:
- Passive network monitoring that understands industrial protocols and device roles
- Asset identification + communication baselining (who talks to whom, how, and how often)
- Threat and anomaly detection mapped to OT reality (writes, mode changes, ladder logic downloads, scanning behavior, unusual engineering activity)
- Risk context (zone/cell location, criticality, vulnerability posture, remote access exposure)
A practical definition
If you want a field-usable definition that cuts through marketing:
Industrial IDS = passive monitoring + OT asset inventory + protocol-aware detections + baselines + investigations.
Industrial IPS = selective enforcement at choke points, usually via firewalls/NAC/remote access controls triggered by detection and runbooks.
In other words, most organizations buy an “industrial IDS/IPS” product and deploy it primarily as IDS/OT NDR first—then add prevention where it’s safe.
IDS vs IPS vs OT NDR: the terms vendors actually use
IDS (Intrusion Detection System)
Classic IDS detects suspicious patterns and alerts. In OT, IDS has evolved beyond signatures into:
- Deep protocol decoding (industrial function codes and operations)
- Behavioral baselining (new talkers, new paths, abnormal rates)
- Asset-centric analytics (device type, firmware family, role, location, criticality)
IPS (Intrusion Prevention System)
IPS blocks traffic in real time. In OT this is complicated because:
- Blocking a control message can break a process
- “False positives” can translate into downtime or safety impact
- Some legacy devices behave unpredictably when traffic is interrupted
OT NDR (Network Detection & Response)
Many OT vendors prefer “NDR” because it implies:
- Passive monitoring (safe by design)
- Detection + investigation workflows
- Integrations for response actions (tickets, SOAR playbooks, firewall updates)
Key insight: In OT security procurement, the label matters less than the deployment reality. Most “industrial IDS/IPS” solutions function as OT NDR with optional enforcement hooks.
Why IPS is risky in OT (and where it does make sense)
Why inline prevention can backfire
OT systems often require:
- Stable timing and predictable flows
- Legacy endpoints with limited stack tolerance
- Tight maintenance windows and strict change management
- Human safety and equipment protection requirements
So putting a strict inline blocker in the wrong place can create “security-caused incidents.”
Where prevention is usually safer
Think in terms of choke points and conduits—places where policy boundaries are already expected:
- Remote access: vendor VPNs, jump hosts, privileged sessions
- IT/OT boundary: firewall between enterprise and industrial DMZ
- OT DMZ: historian replication, patch staging, remote tooling
- Inter-zone conduits: between Level 3 and Level 2, or between cells
- Known vendor skids: tight allowlists on required ports/protocols
- Wireless/serial gateways: strict allowlists and rate controls
The OT-safe approach to “IPS”
Instead of “block everything suspicious,” OT teams often succeed with:
- Detect suspicious behavior with OT NDR
- Validate with context (asset role, zone, maintenance activity)
- Contain using least risky control (e.g., restrict remote session, tighten firewall rule, isolate at switch port when safe)
- Recover with an OT-aware playbook (coordinate with operations)
This is why a platform’s workflow design is often more important than whether it claims “IPS.”
How industrial IDS/IPS fits the Purdue model (monitoring map)
Even if your organization is moving beyond strict Purdue diagrams, the mental model remains useful for deciding where to monitor first.
Purdue-style monitoring priorities
High-value monitoring points (deploy first):
- IT ↔ OT DMZ boundary
- OT DMZ ↔ Level 3 (site operations)
- Level 3 ↔ Level 2 (area/cell) conduits
- Remote access ingress/egress points
- Critical process cells (where consequences are highest)
Simple monitoring map
Enterprise IT (L4/L5)
|
[Firewall / Proxy]
|
Industrial DMZ (3.5) —- Remote Access / Jump Hosts / Historian Relay
|
[Firewall / Conduit Controls]
|
Site Operations (L3) —- Site Services (AD replicas, patch staging, backups)
|
[Cell/Area Conduits]
|
Control Networks (L2) —- HMIs / SCADA / Batch / DCS controllers
|
Field/IO (L1/L0) —- PLCs, RTUs, drives, instruments, safety
Where IDS/NDR sensors go: on SPAN/TAP copies at the firewall interfaces and key conduits.
Where IPS/enforcement goes (selectively): on the firewalls/remote-access layers already intended to enforce policy.
What to expect from a modern industrial IDS platform
When you evaluate Claroty vs Nozomi vs Dragos (or any OT detection platform), anchor your expectations around these capabilities.
1) Asset visibility that actually works in OT
A good OT IDS/NDR should answer:
- What devices exist (including unmanaged/legacy)?
- What industrial protocols do they speak?
- Which assets are controllers, operator stations, engineering workstations?
- Which assets are safety-related or process-critical?
- Where do assets sit (zones, cells, sites)?
Watch for: visibility that depends only on IT-centric identification. OT needs protocol-aware attribution.
2) OT-specific detections (not just IT detections)
You want detections that understand operations, such as:
- Unauthorized write operations to controllers
- New programming/logic download behavior
- Unexpected device mode changes
- New inter-zone communications (policy drift)
- Scanning and discovery activity inside OT
- Abnormal remote access usage patterns
Watch for: alert floods that don’t map to actionable OT decisions.
3) Baselining and drift detection
OT networks are repetitive—this is a strength. A platform should:
- Learn normal cyclic communications
- Flag drift (new talker, new path, new function)
- Allow you to approve expected changes (maintenance windows, vendor work)
Watch for: tools that baseline poorly in plants with frequent changeovers.
4) Investigation and evidence
Your SOC and OT engineers will ask:
- What happened, to which asset, on which protocol, from where?
- Was it a read, write, program download, or configuration change?
- Can we tie it to a user session or remote access entry?
Watch for: solutions that detect but can’t support incident triage.
5) Integrations that reduce friction
Common integration targets:
- SIEM (central analytics and correlation)
- SOAR (playbook-based response)
- Ticketing (ServiceNow/Jira-style workflows)
- Firewalls (policy verification and response)
- NAC (quarantine where safe)
- CMDB/asset systems (single source of truth)
- Vulnerability management (OT-aware context)
Watch for: integrations that are “checkbox” but not operationally usable.
Claroty vs Nozomi vs Dragos: practical positioning
All three vendors are widely recognized in OT security. They overlap in many core capabilities: passive monitoring, OT asset visibility, protocol decoding, and detection. The more meaningful differences usually show up in how they operationalize risk and response, and how well they fit your environment (multi-site scale, regulated requirements, SOC workflow, services).
Below is a practitioner-oriented way to think about each. (Always validate in a proof-of-value, because packaging, modules, and supported integrations change over time.)
Claroty: “OT visibility + enterprise-friendly workflows”
Claroty is commonly evaluated by organizations that want:
- Strong OT asset discovery and inventory
- Clear segmentation and exposure views (zones, conduits, remote access pathways)
- A platform that aligns with enterprise security programs (SOC, SIEM, governance)
- Broader visibility across OT and related environments (often including IoT-like device categories depending on scope)
Where it tends to fit well:
- Enterprises standardizing OT security across many sites
- Teams that need strong reporting for governance and compliance
- Programs emphasizing visibility, asset management, and risk reduction through policy and segmentation alignment
Nozomi Networks: “OT NDR depth + flexible deployments”
Nozomi is often positioned around:
- Protocol-aware monitoring with anomaly detection and baselining
- Deployments that scale from a single plant to large multi-site programs
- Environments where you need adaptable sensor placement and broad protocol coverage
Where it tends to fit well:
- Mixed OT environments (manufacturing + utilities + building systems in one portfolio)
- Teams prioritizing detection depth and operational monitoring across many segments
- Rollouts where distributed sensing and central visibility are key
Dragos: “OT threat focus + incident-driven outcomes”
Dragos is widely associated with:
- Strong emphasis on OT threat scenarios, triage, and operational response
- A narrative centered on industrial threat behavior and high-consequence environments
- Programs that value intelligence-driven prioritization and response readiness
Where it tends to fit well:
- Critical infrastructure and high-impact manufacturing
- Organizations that want mature incident-handling workflows and threat-informed operations
- Teams seeking a solution that aligns closely with OT IR and consequence management
Important: The best choice often depends less on brand and more on:
- Your architecture (flat vs segmented OT)
- Your response model (SOC-led vs OT-led vs hybrid)
- Your scale (1–3 sites vs 30–300 sites)
- Your tolerance for inline controls and automation
Comparison table: what to evaluate (not what to assume)
Use this table as a scorecard template. Replace “High/Med/Low” with your findings after demos and a proof-of-value.
| Category | What “good” looks like in OT | Claroty (score) | Nozomi (score) | Dragos (score) |
|---|---|---|---|---|
| Asset discovery & attribution | Identifies PLCs/RTUs/IEDs/HMIs/EWS accurately using protocol evidence | |||
| Protocol decoding depth | Understands OT operations (reads/writes/programming) not just ports | |||
| Baselining & drift | Learns normal comms and flags policy drift with low noise | |||
| Detection quality | Actionable detections tied to OT consequence and asset roles | |||
| Remote access visibility | Sees pathways, sessions, and unusual access patterns | |||
| Segmentation insights | Maps zones/conduits and shows “should vs is” comms | |||
| Response workflows | Clear triage, evidence, and OT-safe playbooks | |||
| Ecosystem integrations | SIEM/SOAR/ticketing/firewalls/NAC/CMDB usable in practice | |||
| Multi-site scale | Central mgmt, distributed sensors, role-based access | |||
| Reporting & compliance | IEC 62443/NIST-style reporting and audit-friendly evidence | |||
| Services & enablement | Vendor expertise helps you operationalize, not just deploy | |||
| Ease of rollout | Fast time-to-value with minimal OT disruption |
Tip: separate “platform” from “program”
A detection platform does not equal a detection program. Score vendors on:
- How quickly your team can reach “steady state” operations
- Whether alerts map cleanly to who owns the action (OT vs IT vs vendor)
- Whether the platform helps you reduce risk measurably (fewer exposures, faster triage, fewer unknown assets)
Use-case fit: which vendor tends to align with which environment
Rather than picking a winner, align your choice to your operating model.
If your #1 goal is “visibility and inventory we can govern”
You likely need:
- Accurate asset inventory and classification
- Risk reporting and ownership mapping
- Support for segmentation projects
- Strong integration into enterprise GRC/security workflows
Often a good fit: solutions that emphasize asset management, exposure mapping, and governance-friendly reporting (commonly how Claroty is evaluated).
If your #1 goal is “deep monitoring across many segments and sites”
You likely need:
- Strong baselining and anomaly detection
- Flexible sensors and good centralization
- The ability to handle varied protocols across plants and regions
Often a good fit: solutions commonly positioned for flexible multi-site NDR-style monitoring (often how Nozomi is evaluated).
If your #1 goal is “threat-informed detection and OT incident outcomes”
You likely need:
- Strong triage workflows and investigative context
- Threat-informed prioritization
- IR-aligned playbooks for containment and recovery
Often a good fit: solutions commonly associated with threat-driven operations and OT incident alignment (often how Dragos is evaluated).
If you’re an MSSP or you want a managed detection model
Ask each vendor:
- How multi-tenant access and RBAC works
- Whether customers can isolate data by site and business unit
- How alert routing and escalation is handled
- Whether APIs support automation at scale
Architecture patterns: sensors, SPAN/TAP, DMZ, and multi-site rollouts
Pattern 1: “Minimum viable visibility” (fastest to deploy)
Start by monitoring the highest leverage choke points:
- IT/OT boundary (outside and inside)
- OT DMZ ↔ Level 3
- Remote access entry/exit
Pros: fast time-to-value, low disruption
Cons: less visibility inside cells; lateral movement may be harder to pinpoint
Pattern 2: “Zone/conduit monitoring” (best practice for mature segmentation)
Place sensors at:
- Conduit firewalls between Level 3 and Level 2
- Key process cells
- Critical skids and vendor boundaries
Pros: best fidelity for policy drift and lateral movement
Cons: more sensors and coordination, more switch config/TAP work
Pattern 3: “Distributed plants + central SOC”
Use local sensors with central management and SOC access.
What to plan for:
- Bandwidth and data retention
- Role-based access (site engineers vs corporate SOC)
- Standard naming (sites, lines, cells, asset owners)
- Standard playbooks and change windows
SPAN vs TAP: what OT teams choose
SPAN/mirror port
- Pros: easy, cheap, fast
- Cons: can drop packets under load, depends on switch configuration
Network TAP
- Pros: higher fidelity, less dependent on switch
- Cons: cost and installation complexity
Best practice: use SPAN for rapid pilots; use TAP where fidelity matters (critical conduits, forensic needs).
Operational workflows: from “alert” to OT-safe response
The best OT detection program turns alerts into controlled action without disrupting operations.
The OT alert triage funnel
- Classify the event
- Is it IT-like (scan, brute force, SMB) or OT-like (write, program download)?
- Assess consequence
- What asset role is involved? Controller vs workstation vs historian
- Validate operational context
- Maintenance window? vendor activity? planned change?
- Contain safely
- Prefer least disruptive control: restrict remote access, tighten firewall, isolate only with operations approval
- Recover and learn
- Update allowlists, baselines, and playbooks; document root cause
What great platforms do in practice
Great OT detection platforms reduce the “human tax” by:
- Explaining why an alert matters in OT terms
- Providing a clean evidence trail (who talked, what operation, what changed)
- Routing the alert to the right owner (OT engineer vs SOC analyst vs vendor)
- Supporting a repeatable playbook (ticket templates, escalation paths)
RFP checklist + demo scripts (questions that force clarity)
Use these questions to avoid “checkbox demos” and expose real differences.
A) Asset inventory and protocol depth
- Show me a PLC and prove how you identified it (protocol evidence, not just MAC/OUI).
- Show device role classification: PLC vs HMI vs engineering workstation vs historian.
- Show the top industrial protocols you decoded in this plant capture.
- How do you handle NAT, routed OT, and duplicated IP spaces across sites?
B) Detection quality and noise control
- Show me how you detect unauthorized writes vs reads for a common OT protocol.
- Show a “new talker to controller” event and how you reduce false positives.
- How do baselines adapt during changeovers or batch operations?
- What’s your process to tune alerting without blinding detection?
C) Segmentation and policy validation
- Show “should vs is” communications for a zone/cell.
- Can you export recommended firewall rules or allowlists?
- How do you support conduit monitoring across Level 3 ↔ Level 2 boundaries?
D) Integrations and response
- Demonstrate a full workflow: alert → ticket → escalation → closure.
- Show SIEM integration: what fields and context are included?
- Can your platform trigger SOAR playbooks? What actions are safe and common?
- Do you integrate with NAC for isolation—and how do you prevent unsafe quarantines?
E) Scale, operations, and ownership
- What does multi-site look like with 50+ plants?
- How do you separate access by site, business unit, and vendor?
- What’s the typical staffing model to run this (SOC + OT engineering)?
- What are your recommended KPIs (asset coverage, drift reduction, MTTR)?
F) Proof-of-value success criteria (define before you buy)
Define measurable outcomes such as:
- Reduce “unknown assets” by X%
- Identify top Y risky conduits and remediate allowlists
- Detect unauthorized OT write attempts in a controlled test
- Cut alert noise to a defined threshold with documented tuning
90-day rollout plan (realistic, OT-friendly)
Days 0–30: Visibility foundation
- Deploy sensors at IT/OT boundary, OT DMZ, remote access
- Establish naming standards (sites/zones/cells/asset owners)
- Integrate with ticketing (even if SIEM comes later)
- Create initial baselines and “expected changes” workflow
Deliverables: asset inventory v1, top talkers map, conduit visibility, initial alert categories
Days 31–60: Detection tuning + segmentation insights
- Expand sensing to key Level 3 ↔ Level 2 conduits
- Tune detections with operations (maintenance window tagging)
- Build OT-safe playbooks (containment options ranked by risk)
- Identify high-value segmentation fixes (allowlist tightening)
Deliverables: tuned alerting, zone/cell communication maps, top 10 drift issues, playbooks v1
Days 61–90: Operationalize response and metrics
- Integrate with SIEM/SOAR where appropriate
- Run tabletop exercises (remote access compromise, engineering workstation compromise)
- Establish weekly OT security review: drift, exceptions, and remediation progress
- Formalize KPIs and reporting cadence
Deliverables: incident workflow, metrics dashboard, quarterly roadmap, audit-ready evidence
FAQ
What’s the difference between industrial IDS and OT NDR?
They overlap. Industrial IDS traditionally means detection, but modern OT products add asset context, baselining, investigation, and response workflows—often marketed as OT NDR.
Do I need industrial IPS?
Most organizations start with IDS/NDR and add selective prevention at remote access and conduit firewalls. Full inline IPS inside control cells is uncommon unless the process and architecture support it.
Can I deploy industrial IDS without downtime?
Usually yes—because sensors can be deployed passively via SPAN/TAP. The main work is switch configuration, access approvals, and validation with operations.
Will this replace my firewall and segmentation projects?
No. OT IDS/NDR complements segmentation by showing policy drift and unexpected flows, and by helping you build and validate allowlists.
Claroty vs Nozomi vs Dragos: which is “best”?
The best platform is the one that matches your operating model and produces measurable outcomes in your environment. Run a proof-of-value with clear success criteria: coverage, noise level, time-to-triage, and actionable remediation.
Closing: how to choose with confidence
If you remember one thing: industrial IDS/IPS is mostly about safe visibility and actionable detection—not aggressive blocking. Claroty, Nozomi Networks, and Dragos can all anchor an OT detection program, but the right choice depends on:
- Your architecture (flat vs segmented, number of conduits, remote access complexity)
- Your operating model (SOC-led vs OT-led vs hybrid)
- Your scale (single plant vs global rollouts)
- Your desired outcome (inventory, segmentation validation, threat-driven response)
