Understanding Zero Trust in Modern Network Security

Do you know what? Despite having worked in network security for pretty much three decades (I started as a pesky network admin in ’93 – pah! I’m old school), I still get a kick out of Zero Trust. Just returned from DefCon, still working my way through hardware hacking village detritus, and I can’t help but marvel at how far we’ve come since the days of perimeter security. But here’s the deal, most companies are still depending heavily on perimeter-based defenses and firewalls just like they are some kind of super magic shield. Spoiler: they’re not.

Perimeter Security Weaknesses

Well, it’s the early 2000s and the Slammer worm is attacking PSTN lines. Back then, our strategy was relatively simple: erect a wall around your network and keep the bad guys from getting in. Firewalls were our moat and drawbridge. And yeah, it sorta, kinda worked — for a little while.

But the problem with perimeter security is that all the people inside the network are trusted. And if someone does get in, boom — the whole kingdom is compromised.

• Attackers are not knocking only at your front gate anymore. They arrive through third-party vendors, phishing, stolen credentials.

The Age of the Cloud and remote work has rendered network borders nebulous. Your border is no longer a clear line.

• Flat firewalls can’t see lateral movement if the attacker evades the edge.

And I’ve witnessed this firsthand, particularly when assisting banks transition to Zero Trust recently. Old-school perimeter thought falls apart when your users are, quite literally, everywhere.

Here’s the thing: Perimeter firewalls alone are like locking the cell doors of a prison and leaving the over-the-wall ladder right outside. Could deter casual thieves, but ones who really want the stuff? Before you realize it, they’ve snuck in.

Zero Trust vs. Firewall Rules

Here is the rubber meeting the road. Zero Trust is not just a new feature of the firewall or a catchy branding term. It’s an entirely other approach to security.

Traditional firewalls? They rely on static rules defined for IP addresses, ports, and protocols. It’s this, if this, allow type logic. But guess what? Networks used to be static. Not anymore.

Firewalls in Zero Trust world work on the concept never trust, always verify.

• Access is dynamic it’s not just about where you are (location), but who you are (identity),
• the device you’re using,
• the time of day,
• the sensitivity of the resource that you’re trying to access.

You recall when I bailed out those three banks? The old firewall was full of holes – too much subnet access couched in too many static rules. Zero Trust afforded us the granularity of control that drastically shrunk our attack surfaces.

Here’s the thing: instead of building higher walls, you need smarter doors.

Identity-Based Controls

All right, firewalls were king you thought, and then you hear about identity in Zero Trust.

Legacy perimeter security largely authenticates once — say at VPN login — and then you’re assumed to be good to roam around inside. Big mistake.

Identity associated controls make both user and device identity a first class citizen for every request.

• Who is it?
• What’s their role?
• Is their device compliant?

In reality, this translates to interfacing with identity providers and using multi-factor verification at all opportunities. No more type your password in and get in bullshit.

And I’ll be honest, I used to rant about stupid complex password policies making long passwords and making you reset them periodically; it’s bullshit and user hostile. Zero Trust solutions go beyond that, with emphasis on continuous verification.

Because, well, heads up: if your identity controls are weak, your firewall rules won’t save you.

Least Privilege Enforcement

Least privilege is one of the most impactful Zero Trust principles. You get access only to what you need. Nothing more.

(It’s also quite weak in traditional perimeter setups.) You climb inside, and hey, much of the network is open. And I’ve watched admin accounts roam unfettered through internal networks for no good reason.

In ZTAs, we apply custom access control lists. It’s very fine-grained in terms of permissions:

• No single username or application should hold more ubiquitous access than needed.
• Access privileges are reviewed and removed as soon as they are no longer in use.

Think of it the way you might a kitchen, where each cook has access to only his or her knives and pots — not the general pantry. Yes, slower at some times — but way safer.

At PJ Networks, a lot of our time is spent helping clients transform their access controls into something that works without being a bureaucratic nightmare.

Continuous Monitoring

And this is where Zero Trust literally obliterates perimeter-centric models: continuous monitoring.

Perimeter protection in many instances is reactive. Detect an intrusion? Maybe. Monitor what happens inside? Often a big no.

Zero Trust systems are akin to putting a security camera on every corner, with AI-created (okay, I’m skeptical of AI-driven hype — but this is actually useful) alerts for anomalous behaviors in real time.

We tell our clients:

• Assume you will be breached.
• So keep everything under constant surveillance.
• Employ analytics to detect anomalies.
• Automate as many responses as you can to reduce dwell time.

Unless you have done this, they say, your cybersecurity posture is not future proof.

Quick Take

For the time crunched, here’s a brief overview:

• Perimeter Security: Old-school, trust within. Quick to get through if they are breached.
• Zero Trust Firewalls: Identity-based, dynamic and granular access controls.
• Identity-Based Controls: Continuous verification, not just at logon.
• Least Access: Only as much as necessary, nothing more.
• Continuous Monitoring: Identify, respond to and evolve in real time.

Final Thoughts

Now, I’m not saying perimeter security is worthless. It’s part of the foundation. But if you still think it’s the defense, you’re behind the curve.

From banging firewalls closed in the 90s to running PJ Networks and helping banks apply Zero Trust to their business — I’ve lived this journey. It’s frustrating to see some companies throwing cash at AI-powered black boxes while not fundamentally rethinking identity and access management.

Here’s my provocative point: No fancy firewall product is going to solve a weak identity strategy, or sloppy user behavior, period. First invest in people, policies, and ongoing verification.

If you’re looking to begin your Zero Trust road trip (which you should have started yesterday), don’t just accept stuff. Focus on:

• Knowing your users and your devices.
• Your sensitive data and applications need to be fully mapped.
• Applying the principle of least privilege.
• Establishing continuous monitoring.

And if you want some sanity or someone who has been through the shell shock (and still drinks copious amounts of coffee) Then PJ Networks is ready.

Because let’s be honest — security is not just a technology issue. It’s a mindset shift.

So get your third cup and crank that console, and be thinking Zero Trust!