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OT Security · Diode Modernization

When the diode isn't enough.
Replace it without losing isolation.

Modern OT operations need RDP to SCADA, SSH to production systems, real-time APIs, and controlled vendor access. truePass Gravity delivers all of it - under the same isolation principle that diodes were built to enforce.

Why it works.

Software-based · No hardware replacement
Aligned with NIST 800-82 · IEC 62443
Deploys in days, not months
01 When diodes become a bottleneck

Three signs your diode is being pushed beyond its design.

If you're seeing one or more of these in your environment - operational pressure has already outgrown what the diode was built for.

/ 01

Workarounds are appearing

Engineers tunnel sessions through bastion hosts. Vendors get permanent VPN access. Files move via USB sticks because the diode-MFT path is too slow. The very isolation the diode was meant to enforce is being eroded by everyday operational pressure.

/ 02

Point products are stacking up

A diode for one-way transfer. A proxy for SMB. A TCP connector for one API. A bastion for SSH. Each addition has its own console, its own logs, its own policy model. Unified security oversight becomes impossible.

/ 03

Audit and compliance break down

Regulators ask "who accessed this SCADA console at 03:14?" The answer requires correlating five different log sources, two of which don't capture user identity. Per-request policy enforcement is missing where it's needed most.

A physical data diode is not Zero Trust compliant. It enforces direction at the wire, but it can't verify identity, apply per-request policy, or produce a unified audit trail - the controls Zero Trust requires. Bolting point products around it doesn't close that gap; it widens the attack surface.

02 The TerraZone approach

One platform. Three layers.
Same isolation principle.

truePass Gravity replaces the patchwork of point products around your diode boundary with a unified software platform. It enables interactive operational connectivity - RDP, SSH, HTTP, Web Services, API, CIFS/ SMB - while preserving the core architectural principle: OT-initiated outbound communication only. No inbound ports. Ever.

Where a physical diode controls direction at the wire level, Gravity controls connectivity at the identity, policy, and audit level - extending isolation from a single boundary point to your entire operational envelope.

Want the full architectural breakdown?
Three-layer architecture · Reverse Access™ · SMB Proxy · Zero Trust App Access
See Gravity page
03 The flow

From identity check to audited session.

01

Identity verification

User authenticates with Active Directory, MFA, and device posture check. No identity → no access. Period.

02

Outbound from OT

The Access Controller inside your OT network initiates an outbound 443 TLS connection to the Gateway in the DMZ. No inbound firewall rules.

03

Per-request policy

Every session, every file action, every API call evaluated against policy in real time. Least-privilege by default. Time-limited by design.

04

Unified audit trail

Single audit log for every action. Exported natively to Syslog, SIEM, and SOC platforms. One source of truth for compliance.

05 Where this applies

Real scenarios. Real environments.

These are the operational situations where teams have already moved from physical diodes to truePass Gravity.

Operators access engineering workstations and SCADA consoles via RDP from corporate or external networks. Per-session MFA. Clipboard, printer, and port controls. Full session recording. No VPN tunnels into OT. No exposed RDP gateways.

Equipment vendors access specific PLCs or controllers for scoped maintenance windows. Time-limited access. Per-user identity. Full audit. The vendor never gets network-level access - only what's needed, when it's needed.

Real-time API integrations between OT and IT zones - for production analytics, predictive maintenance, ERP integration. Bidirectional where business requires; unidirectional where security requires. Always under one policy.

Configuration files, firmware updates, engineering documents moving between zones pass through CDR sanitization, identity verification, and policy enforcement. No more USB sticks. No more uncontrolled FTP.

06 The outcomes

What changes when you make the shift.

Per-user accountability

Every action tied to identity, not just IP.

Unified audit

One log. One policy. One console.

Interactive connectivity

RDP, SSH, HTTP, API, SMB - no more workarounds.

Same isolation principle

Outbound-only, no inbound ports. Ever.

No infrastructure changes

No firewall rewrites. No re-architecture.

Compliance ready

NIST 800-82, IEC 62443, NERC CIP - out of the box.

Replace your diodes

without losing isolation.

A 30-minute consultation with our security architects. We'll map your current diode-and-point-product setup, identify what Gravity replaces and what it complements, and propose a tailored Proof of Concept.

Current diode & air-gap architecture review
Tailored Proof of Concept
Isolation preserved, connectivity added
Talk to an architect

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