Plug-and-Play NIS2 Compliance: Achieving Coverage Without Agents or Cloud Dependency
Achieve NIS2 compliance with plug-and-play, agentless solutions for industrial networks. Secure, monitor, and report without cloud reliance or system disruption.
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Plug-and-Play NIS2 Compliance: Achieving Coverage Without Agents or Cloud Dependency
The European Union’s NIS2 Directive is reshaping the landscape of cybersecurity for essential and important entities across sectors such as energy, transport, health, and digital infrastructure. Unlike its predecessor, NIS2 dramatically increases the obligations for risk management and incident reporting. With deadlines looming, many CISOs and operational technology (OT) teams are searching for practical and sustainable approaches that ensure compliance but don’t introduce complexity or dependencies antithetical to industrial environments. Notably, the modern industrial perimeter rarely accommodates agent-based solutions or cloud dependence.
This article sets aside marketing platitudes in favor of a forthright, technical exploration: How can organizations achieve NIS2-aligned monitoring and control—at scale—by using plug-and-play, agentless, offline-capable techniques, aligned with real-world constraints found in critical infrastructure?
NIS2: Revisiting the Mandate For Security Posture Management
To manage cyber risk to critical infrastructure, NIS2 Article 21 specifies “appropriate and proportionate” technical and organizational security measures. While the requirement language intentionally avoids prescriptiveness, several technical obligations shine through:
Continuous risk and threat assessment
Protection of network and information systems, including asset management and network security
Incident detection and response capability
Secure configurations and vulnerability management
Supply chain and third-party risk management
Whereas traditional IT environments have leaned on endpoint agents, remote SaaS platforms, and constant connectivity, most critical infrastructure networks are built on a different set of assumptions:
Limited or no cloud connectivity, often by explicit policy
Legacy assets or embedded controls lacking support for endpoint agents
Change-averse and certified systems where updates equate to risk
For these environments, what does “plug-and-play NIS2 compliance” truly mean?
Agentless Security: The Architectural Roots and Evolution
Historical Perspective: Why Agentless?
The concept of agentless security is far from new. Early network monitoring systems (think SNMP-based monitoring in the 1990s, or NetFlow spawned from Cisco in the late 90s) took shape precisely because most network devices and industrial endpoints were incapable of hosting third-party software. The principle was simple: observe behavior from the outside using side-channel data—whether it’s mirrored network traffic, flow exports, or management interfaces.
In OT, the situation is even starker. PLCs, RTUs, and field devices rarely even offer the APIs required for agents, and the margin for error in production is low. The only safe approach is out-of-band analysis, minimizing the chance of system disruption.
Plug-and-Play: Evolution from SNMP to Passive Monitoring
Passive monitoring with network taps or SPAN ports became the lingua franca of OT security by necessity, not technological preference. In these scenarios, devices such as industrial firewalls or specialized probes (for example, early Lancope StealthWatch, Dragos, Nozomi) became de facto sources of situational awareness. The advantage? No device configuration, no downtime, no risk to critical process controllers.
Policies could then be tuned from outside the process, and traffic analysis formed a baseline for detecting unusual behavior. Agentless, plug-and-play coverage meant simply plugging a device into a mirror port.
Plug-and-Play Coverage: Modern Building Blocks
With OT networks increasingly converged with IT—and NIS2 ratcheting up compliance requirements—a modern plug-and-play solution typically revolves around these architectural patterns:
Network Traffic Analysis (NTA): Passive sensors ingest mirrored traffic, reconstructing sessions, building asset inventories through protocol decoding (Modbus, DNP3, S7, OPC-UA), and providing behavior-based anomaly detection. No endpoint agent, zero impact on process.
Configuration Assessment via Network Management Protocols: Leveraging SNMP, SSH, or industrial protocol queries to pull configurations from switches, routers, and sometimes even legacy OT endpoints—again, without deploying new software to endpoints.
Log Aggregation: Central log collection (e.g., syslog) for events from firewalls, switches, and industrial security gateways. This requires endpoint configuration but no agent installation.
Disposable, Portable Probes: With systems like Raspberry Pi or industrial x86 boxes, probes can be temporarily dropped into the network for point-in-time assessments, moved as needed, and shutdown leaving no local footprint.
Annotation: The term “plug-and-play” here is more operational than technical. It implies that deployment is non-invasive, can be completed during scheduled downtime (or none at all), and won’t change the state or configuration of monitored assets.
Cloudless by Design: Edge-Centric Compliance
Although many compliance offerings have shifted to SaaS, industrial and critical environments frequently operate air-gapped or within tightly-managed DMZs. From an architectural standpoint, compliance coverage should not be predicated on external cloud access. Key considerations:
On-premises management consoles: Hosting the brains of detection, reporting, and policy management within a local rack minimizes dependency and latency.
Local retention and reporting: NIS2’s incident and audit requirements can be satisfied with reports generated and archived locally, reducing leak or privacy risks.
Integration via standard protocols: Industrial standards support syslog, SMB/NFS, and legacy email for alerts/reports. Modern cloudless deployments build around these primitives for local workflows.
Removable data transfer: For fully air-gapped environments, periodic data exfil (e.g., via encrypted USB) can support centralized compliance evidence without violating segmentation practices.
Historical Note: The design ethos of early SCADA and DCS networks was one of isolation, not just for security, but for operational autonomy. While the “air-gap” is no longer absolute in most environments, cloudless designs remain valuable for respecting these original intent and operational constraints.
IT/OT Collaboration: Misconceptions and Pathways
As the firewall between IT and OT erodes (often more in practice than in principle), many compliance headaches stem from differing assumptions:
IT expects manageability via endpoint agents, centralized control, and rapid patching
OT expects process uptime, minimal change, and operational continuity trumping security mandates
Plug-and-play, agentless security acts as a bridge. By adopting network-centric visibility, neither party must cede control: IT can impose reporting and monitoring requirements without rewriting OT’s rulebook for change management or asset intervention. Many industrial deployments use joint governance models, with the sensors managed by IT but operated close to the OT boundary.
Architectural Practices for Success
Establish clear zones and conduits: Use network segmentation to isolate critical assets and subject only the conduit flows to monitoring, minimizing surveillance scope and blast radius.
Operationalize context sharing:
Feed network-derived asset inventories and threat data to both IT and OT dashboards. Use open standards (OPC-UA, REST, STIX/TAXII) for compatibility.
Decouple monitoring from control:
Plug-and-play, agentless tools should have no capacity to write or influence operational processes. This constraint reassures OT leads and simplifies compliance audit narratives.
Deploying Plug-and-Play Coverage: Steps, Pitfalls, and Reality Checks
Step-by-Step Approach
Identify Monitoring Points:
Map network topology and select SPAN or TAP locations that provide maximal coverage for both IT and OT segments, but avoid production-critical links during business hours.
Install and Baseline:
Deploy sensors/probes, tune traffic capture, and baseline “normal” operations for behavioral analytics. Most learning periods range from days to a few weeks.
Policy and Threshold Definition:
Define what constitutes a significant event or policy violation under NIS2. This includes unauthorized connections, rogue asset behavior, and configuration drift.
Incident Drill:
Simulate incidents—disconnects, policy violations, malicious behavior—to assess not just detection, but incident workflow and on-premises reporting.
Integrate and Iterate:
Connect outputs to incident response, feed inventory data back to asset management, and update baselines as the environment evolves.
Common Pitfalls
Misplaced SPAN ports or overburdened mirror links leading to lossy packet capture
Ignoring encrypted traffic, which can hide both incidents and compliance violations (TLS fingerprinting at minimum can help)
Assuming “agentless” means “zero risk”—network-based sensors can still run afoul of legacy hardware with duplicate MAC entries or topology change quirks
Overreliance on “default” behavioral baselines—customization per process area is required
Conclusion and Forward Look
NIS2 pushes industrial and critical infrastructure environments toward visibility, monitoring, and control expectations closer to their IT peers—without accommodating for the entrenched realities of operational context, device heterogeneity, and process safety. Plug-and-play, agentless, and cloudless architectures offer practical coverage without the downsides of invasive agents or risky external dependencies. They work by revisiting foundational networking techniques, using modern processing and analytic capabilities, and aligning with the historical intent of SCADA and OT network design.
If there’s a final lesson: compliance coverage in industrial contexts arises not from “deploying more products”, but from sober technical design—balancing visibility, operational safety, and regulatory need. The plug-and-play approach demands ongoing diligence, genuine collaboration between IT and OT, and a healthy skepticism for one-size-fits-all solutions.
References
About the Author
An engineer with a decade-plus patchwork across IT, industrial, and process environments—keenly aware that “ease of deployment” seldom means “ease in production”. Nothing said here is marketing; everything is meant as field advice.
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