Zero Trust for OT Networks. On-Premise. Agentless.
Zero Trust for OT on-premise means enforcing identity-based access at the network boundary instead of on the asset, because most OT devices cannot run security agents. This is the entry point to Trout's architecture guides, comparisons, and CISA-aligned playbooks for deploying it without disrupting production.
What is Zero Trust for OT?
Zero Trust for OT means no connection to an operational technology asset is trusted by default. Every user, device, and session must be authenticated and authorized before accessing PLCs, HMIs, SCADA systems, or any other OT resource. Unlike IT Zero Trust, OT Zero Trust must work without endpoint agents, without disrupting production, and often without internet connectivity.
Why OT Zero Trust is Different.
Four properties separate OT Zero Trust from IT Zero Trust. Each one has architectural implications. Each one is endorsed in the April 2026 CISA guidance.
Agentless on the Asset
PLCs, HMIs running Windows XP, SCADA servers, and ten-year-old engineering workstations cannot host an agent. CISA's April 2026 guidance endorses agentless deployment for legacy OT and recommends pairing it with active enforcement at the network boundary, not just passive monitoring.
Microsegmentation Without Redesign
Conventional microsegmentation requires VLAN redesign and re-IP'ing, which most production plants cannot accept. Overlay-based microsegmentation enforces per-asset, per-protocol, per-session policy on top of the existing physical network. The Layer 2 topology does not change.
Compensating Controls for the ICAM Gap
Most installed-base OT predates Active Directory, SAML, or OIDC. CISA endorses compensating controls above the device level, including segmentation as a valid compensating control. Identity is enforced at the network boundary, on behalf of assets that cannot present it themselves.
Lateral Movement is the Real Threat
Volt Typhoon and similar actors compromise IT, then pivot to OT through whatever access path exists. Air-gapping alone is not a control: CISA explicitly warns against the false sense of isolation. Every IT-to-OT session must be authenticated, authorized, and logged, not merely inventoried.
Zero Trust OT Solutions on Trout Software.
Zero-Trust Access Control
Identity-based access control with MFA, RBAC, and protocol-level enforcement for on-premise environments.
Read moreIndustrial DMZ
Proxy-based segmentation that isolates OT assets without network redesign.
Read moreRemote Access
Zero-Trust remote access for vendors, contractors, and OEM technicians. Session-scoped, MFA-enforced, fully auditable.
Read moreNetwork Visibility
Passive asset discovery across IT, OT, and IoT. Build a dynamic inventory without active scanning.
Read moreAir-Gapped Deployment
Full Zero Trust enforcement in disconnected environments with no cloud dependency.
Read moreArchitecture Guides and Whitepapers.
DoD Zero-Trust OT Alignment Guide
Point-by-point mapping of DTM 25-003 requirements to Access Gate capabilities across all 7 DoD OT-ZT pillars.
ViewBeyond Purdue: Micro-DMZs for Modern OT
Why the Purdue Model fails with remote access, IIoT, and cloud analytics. How Micro-DMZs deliver per-asset Zero Trust boundaries.
ViewIndustrial DMZ Design Patterns
Four architecture patterns for proxy-based segmentation in OT networks.
ViewOverlay Networks Explained
How the Access Gate builds a secure virtual layer on top of your existing industrial network.
ViewSecuring Modbus in Industrial Environments
Architecture and security controls for a protocol that was never designed to be connected.
ViewZero-Trust in Operational Environments (Webinar)
Recorded session on why network segmentation and authentication should have evolved over the last 20 years.
ViewAccess Gate vs. Alternatives.
Access Gate vs. Claroty
On-premise enforcement vs. cloud-based OT monitoring.
CompareAccess Gate vs. Nozomi
Visibility plus enforcement vs. visibility-only monitoring.
CompareAccess Gate vs. Forescout
Zero Trust session control vs. network admission control.
CompareAccess Gate vs. Zscaler
On-premise Zero Trust vs. cloud-routed Zero Trust.
CompareAccess Gate vs. Firewalls
Identity-based enforcement vs. port and IP rule-based filtering.
CompareOverlay Networking vs. VLANs
Software-defined segmentation vs. switch-level VLAN reconfiguration.
CompareZero Trust OT Articles.
By Industry & Regulation.
NY Water Cybersecurity Compliance
How Access Gate maps to the EFC 12-step checklist, DEC/DOH regulations, and NIST CSF 2.0. Jan 1, 2027 deadline.
Read more Electric UtilitiesNERC CIP Compliance Guide
How Access Gate covers CIP-002 through CIP-015 for bulk electric system operators. CIP-003-9 deadline guidance.
Read more Federal / DoDCISA Zero Trust OT Guidance (Apr 2026)
What the joint CISA/DoW/DOE/FBI guidance means for on-premise deployments. Volt Typhoon defense and the agentless endorsement.
Read moreZero Trust OT FAQ.
Access Gate enforces Zero Trust at the network layer for OT environments. No agents on endpoints. No production disruption.
IT Zero Trust typically uses endpoint agents, cloud identity providers, and software-defined perimeters. OT equipment often cannot run agents, may lack modern operating systems, and operates in environments where uptime is critical. OT Zero Trust must work at the network layer without touching endpoints.
No. Access Gate enforces Zero Trust through overlay networking and proxy-based access control at the network layer. PLCs, HMIs, SCADA systems, and legacy equipment are protected without installing any software on them.
Yes. Access Gate connects adjacent to the existing network as an appliance or VM. It creates an overlay network on top of existing infrastructure. No IP changes, no VLAN reconfiguration, no recabling required.
Access Gate runs entirely on-premise with no cloud dependency. All policy enforcement, logging, and identity verification happen locally. It supports fully air-gapped, hybrid, and classified environments.
Access Gate works at the network layer and supports any IP-based protocol. Specific protocol awareness includes Modbus TCP, OPC UA, and common industrial protocols. The proxy layer can enforce access control per-protocol and per-session.
Firewalls filter traffic by IP and port rules. VLANs segment at the switch level. Neither verifies identity. Access Gate adds identity-based access control on top of existing firewalls and VLANs. It does not replace them. It adds the identity layer they were never designed to provide.
Deploy Zero Trust on Your OT Network.
Talk to the Trout team about your environment, deployment options, and compliance requirements.
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