05 August, 2025
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Reflections on Cybersecurity: From PSTN to Zero Trust

Now that I’m three coffees deep, whilst sitting at my desk, I felt the urge to write about some of the realities that I have seen every single day in cybersecurity. I still have remnants of my run as a network admin from way back in 1993 — voice and data muxing over PSTN, long before that was even jargon let alone my daily bread and butter — and have watched this space grow into the monstrous beast it is today. Here is a hidden trick: some things do not change at all, it just gets smarter.

The Early Years — remember PSTN and those clunky multiplexers

At the time, managing voice and data was no different from trying to run a classic through traffic. Every connection was precious. But the change that really kicked my butt? The Slammer worm in 2003. Seeing the devastation — perfect highway structures being crushed under floods of packets — is like a definitely built highway turning into a nightmarish traffic on steroids.

Fast forward to today. Today as CEO of my own cybersecurity company — P J Networks Pvt Ltd, I am in the thick of implementing zero-trust architectures for three large banks. Kind of a different beast, but some lessons from those early days still resonate. Zero trust is more than just a buzzword and really works back to the idea of redefining your perimeter — or let’s be real, blowing it up!

Why am I buzzing? Well, just returning from DefCon must have wired me in the hardware hacking village. Just genius, those guys are, making the waste hardware into new fortresses of innovation I’ve always gotten nostalgic for the older tech seeing hackable and secureable in real time? Inspiring.

What I Missed in Early Network Admin Days

With voice and data multiplexers, the focus was on reliability and resilience.

Old skills like manual troubleshooting of physical lines turned me into an anti-Santa, knowing your network load apparently by listening to it.

Of course cyber attacks then were not as sophistacated (most of the time) but still no less disruptive — Slammer worm to internet was a good wake up call.

In short, if you think your firewall blocks all?! Back then, a fast response was like trying to stem the tide with your hand in the dam.

Yet Another Slammer Worm: A rapid case study reintroduced

Slammer, guys—Shit was faster than lightning — inside a place, all it took was about ten seconds to hit the entire intranet. And I watched it all live — and you taught me.

Why you need patch management
Patching is a thankless job but not patching your system is like keeping your car unlocked in Miami Beach.
The importance of segmentation (Slammer would have otherwise spread all over).
No, incident response isn’t some emergency button you press after the fact. Which it is… sort of like changing the oil in your car engine.

So what is the thing that only a few people noticed — it was not just technology, it was people. It went undetected by the admins, and with reckless user clicking, it was a perfect storm of bad.

Zero-Trust Architectures: The Modern Frontier

Recently working with a bank to implement zero trust made me remember why this model is still so powerful. The zero trust approach is the antithesis of old-school perimeter defense — it’s locking every door in your house, not just the front one. No more implicit trust—always verify.

But here’s the kicker:

No trust — Every access request is authenticated and authorized, all the time

A: Micro-segmentation — breaking networks down into tiny little compartments so that if someone penetrates one they are stuck in just a small part of your system.

Deploying zero trust isn’t a flip-the-switch operation — it requires cultural transformation. And training and an enormous up-front spend.

I need to preface this with a tiny qualifier: zero trust is over-hyped as the be-all end-all of security models by some ( it’s not but we’ll save that for another day). But it’s a fundamental approach to the threat landscape that exists today.

Real-World Zero Trust Tips from the Trenches

Begin small- First recognized your crucial asset
Implement multi-factor authentication everywhere. No excuses.
Always Monitor and log.— Visibility is king
Segmentation is your friend—no lateral movement!
Make your users smarter — they are both your best line of defense and most vulnerable point.

And no, using AI-powered security won’t solve anything. I’m skeptical. AI is excellent at detecting outliers, but a human with industry experience has to have the last word. And always remember: the human hacker is a far more adaptable creature than any algorithm.

DefCon Insights and Hardware Hacking Village Highlights

DefCon always makes me realizesecurity is not a software/firewall discipline alone. The hardware hacking village was a treasure:

They showed how what appears to be hardened hardware can be cracked with nothing more than a soldering iron and some persistence.
Stressed the significance of physical security — often an overlooked part.
Revealed the homeliness of Iot devices – wait until your toaster/fridge are on-network. That thing is a backdoor

That made me start to think about our physical machines and not only their software (that’s why we have firewalls, routers, servers) but also the vulnerabilities that come with them being actual objects rather than just digital dust. I advise all my clients to ask: Is that tamper evident?

Password Policies- My Rant (Buckle Up)

So why do we all still hate passwords? Because people make them awful:

Password123, qwerty, letmein—come on.
Enterprises forcing 90-day resets? Insanity. It is training you to either pick weaker passwords or write them down — opposite of the objective.

Here’s what works:

Use passphrases (recipes, not ingredients).
Implement password managers—no excuses!
Combine with multi-factor authentication.

Forget about complexity rules and pay attention to length and usability.

Sanjay’s Cybersecurity Essentials for the Business Leader

Fast Forward: Cybersecurity & The Role of Detection

You’re not only buying software, you are buying manpower MORE IMPORTANT THAN THATTRAINING
There is no choice left, as zero trust is a necessity to defend against modern threats. But implement thoughtfully.
Patch religiously—patch back enough to keep your defenses in shape.
Continuously monitor network activity and have a fast response.
HARDWARE – Lock down your devices, it’s easy to steal physical security of equipment is even easier to ignore.
Look Behind the “AI-powered” Label AI should be a weapon, not a shield.

Don’t forget, cybersecurity is not a matter of creating the best wall. This is about constructing the most intelligent wall, monitored by vigilant human beings.

Wrapping Up

So much has changed in that time, I mean going from hand-cranking multiplexers for PSTN to orchestrating zero-trust architectures for big banks is not boring. It takes guts to fight for respect in the #cybersecurity field; intestinal fortitude to keep the rigorous learning up and even more stubbornness to stick with it on those days when you just don’t know how many files are waiting in that log-file-made-of-gold. Systems get tired (can you believe I am now four coffees in) but the good work done keeps businesses up and running.

Keeping finger crossed that this post humanizes some of the buzz terms you hear every day. That’s the wrong mentality if you think cybersecurity is just some IT checkbox.

Stay vigilant,

Sanjay Seth

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