Quick Take

• OT is old school and fragile, so Zero Trust must be polished not slapped on.
• ZTNA limits the attack surface by checking identities and devices for state, does not permit access to OT assets.
• Fortinet OT ZTNA supports policy-driven microsegmentation and inspection across the entire OT footprint – from the plant floor to the data center.
• — It’s not that we have to kill productivity; it’s about making the control loops safer, auditable.
• And the ones who envision air-gaps as their defense, are already behind and so are their competition that accepts real-time verification.

I have spent decades watching networks with the faint scent of coffee and old printer toner emanating from a desk. I’m Sanjay Seth, the owner of P J Networks Pvt Ltd, and yes, I remember when your router was no more than an over glorified phone dialer and a mux transported voice and data across PSTN as if it were some kind of disagreeable river. I first became a network admin in 1993, and the floor taught me very quickly that you can believe that plant floor and corporate LAN where like on two different planets. And yes, I’ve watched the Slammer worm roll through a corporate WAN like a wrecking ball — in person, when we were debugging voice/data muxes and hoping no one would be playing under the sprinklers while printers jammed. Now I run a security company, and I still have that shit-kicking-pace coffee habit; it’s the only way to keep up with clients who want things done yesterday. Personally, I have assisted three banks in upgrading their zero-trust approach, demonstrating that OT and IT can share a confident, controlled backbone. Just returned from DefCon and I’m still exciating about the hardware hacking village—the energy makes you remember that if you’re not testing, you’re getting tested on.

OT security challenges

OT networks are a weird melting pot of proprietary protocols, legacy kit and safety-critical automation. The challenges are not just technical; they’re organizational.

• Legacy gear that talks a language your modern IDS barely understands.
• Slow patch cycles because the cost of downtime is measured in millions.
• A culture which believes in “air-gapped” myths more than in continuous monitoring.
• — Vendor sprawl; three suppliers, five credential stores and no single source of truth.
• — Growing need for remote access to engineering stations, but only after you’ve validated all identities and device posture information and contextual data.

And yet the attackers don’t care about your org charts. They’re taking advantage of drift — policy drift, device drift, permission drift — and that’s where ZTNA really stands out.

Access control for engineers

OT access control isn’t about waving engineers in because they have a badge. It’s about giving trusted engineers access to exactly what they need, when they need it — and having everything verified first.

• Verify the identity of users, devices and applications. MFA is table stakes, but device posture counts.
• Role-based, asset-based, time-based and safety state-based segment access.
• Implement dynamic policies that adjust as engineering tasks evolve.
• — Record each and every session, for forensic review; OT stakeholders should be entitled to audit trails that don’t wilt under the heat of a control room moment.

Here’s the thing, however: I’ve seen too many projects where “engineer access” turns into a blanket tunnel. Letting one password get someone to the HMI isn’t doing anybody any favors. Zero-trust is about least privilege, continuous verification and segment-by-segment access.

Microsegmentation

In OT, microsegmentation is just not a buzzword; it’s a disciplined way to minimize blast radius.

• Establish domain of security for each line, line equipment and control system.
• Implement east-west boundary so compromised devices can’t traverse the network.
• Bind policy to asset context—what’s in flight, who is who and where does control flow.
• Employ continuous monitoring to identify abnormalities in commands, data streams or timing.

And yes, you’ll hear grumbles about performance. In practice, modern OT gear can handle it, particularly if you’ve architected the policy properly.

Fortinet OT ZTNA

Fortinet OT ZTNA is no panacea, but it is a great start for connecting the OT and IT worlds with intent.

• — Identity-first access: You authenticate who and what before you have access to OT assets.
• – Context-aware policies: you can consider the state of the plant as well as the current shift and intervals you need to maintain, when making decisions.
• – Built-in micro segmentation: you don’t patch it after the fact, you design into fabric.
• – OT boundaries inspection: safe tunnels which do not affect control loops.
• – Seamless integration with NGFWs, threat intelligence and SD-WAN for policy consistency across sites.

For some “AI-powered” claims — the thing that makes any tech product in 2019 sound good on paper — this is still one of them. I’m wary of anything that’s labeled as AI when it’s really a well-calibrated system of rules, telemetry and anomaly scoring. And yet, you have a platform that can link up a PLC firmware event with a login anomaly and a VPN posture check, you’re not dreaming — you’re actively discarding risk in real time.

Benefits

The advantages of OT ZTNA are not just theoretical. They translate into quantifiable results for the company.

• Smaller attack surface and the benefit of not losing uptime.
• Increased remote engineering capabilities with auditable access.
• Fast incident response by tracking every session.
• Vendor access in a more secure manner by time boxed controlled context aware sessions.
• Acceptance into industry standard requirements becomes easier with transparent control.

But the real cherry on top? It’s practical. It works when you incorporate it into your existing firewall, VPN and asset inventory, not throw in another product silo.

One-liners for the board

• Password policies are also like a nag, but you’ll regret those weak passwords more than you think when that controller goes away.
• Your OT deserves segmenting honouring both safety and security – two aspirations that occasionally contradict each other but not with ZTNA, where you get both.
• If you think OT is still air-gapped, you’re kidding yourself– supply chain, remote engineering and maintenance crews do not care about your chalkboards.

Implementation considerations

• —Begin with asset discovery: know what’s on the floor, not just what you think is there.
• – Create a policy map before you put one rule live otherwise you play chase with false positives for weeks.
• – Start with a high-risk segment first on ramp, scale thoughtfully first to avoid the ramification’s of outages by accident.
• — Trainmas conductors and engineers, security is a workflow, not a punishment.
• – Integrate change management and safety validation — a secure system that is safe when performing an upgrade must remain safe while upgrading.

Industry references

Target, manufacturing and utilities is making clear, OT security it no longer an option; it’s fundamental. The real-world lessons: identity, posture and segment early; digitally record your every move; and prepare yourself for a cultural shift as you transition from trust to verify.

Closing thought

ZTNA for OT isn’t a fad. It’s a commonsense, disciplined way to insure industrial access that was created with the rough and tumble of the plant floor in mind — personally having roots in automation and manufacturing. The technology is a versatile one — when mixed with policy discipline, asset discovery and continuous monitoring, you have a security posture that does not exist in a chronic state of alert fatigue.

Deploying a path to zero-trust for your OT assets? Begin with a high-value pilot: one segment, one maintenance window, and policy mapping that is crystal clear. Then scale. You will find out where your gaps are, where the data is moving and how you can bring the gloves in tighter around the most critical ones.

For the skeptics like me, who are heartily sick of ‘AI-powered’ hype, it’s worth bearing in mind: intelligence isn’t a branding term. It’s a craft — constructed from telemetry, lab-tested configurations and single-minded focus on cutting risk without snapping the gear you’re trying to safeguard.

Sanjay Seth

Sanjay Seth of P J Networks Pvt Ltd

But I probably have more caffeine than sleep, and yes, while scarfing down a burned piece of toast, next update is on deck. The security work never ends, and that’s a good thing—because neither do your operations.