How Firewalls Are Audited by PJ Networks After Upgrade

Here’s the problem with firewalls—they’re the seatbelt of your network. Vital. Life-saving. But only if they are clicked in place and working correctly. And, time after time, I have seen organizations simply upgrade their firewalls and: move on. No post-upgrade audit. No check to confirm that everything is running as expected. That’s a recipe for disaster, my friends.

I’ve been around long enough to know better. Having been a network admin back in 1993 when we were connecting muxes together to get voice and data to communicate with each other over PSTN, I personally have had a front row seat to seeing the evolution of the firewall. I’ve watched the Slammer worm eat through unpatched SQL databases (a real pain in the ass, trust me), and I’ve seen companies grind to a halt because someone forgot to actually secure critical systems. Now, as a cybersecurity consultant and the founder of PJ Networks, I consider it my mission to proselytize the gospel of thorough audits. Especially just after an upgrade to the firewalls.

Now, let’s take a look at what we do when it comes to post-upgrade firewall audits—and why they’re so important to maintaining your data security after an upgrade.

Post-Upgrade Risks

First, what’s keeping me up at night: post-upgrade risk. A firewall upgrade isn’t a “set it and forget it” deal. Yes, you may acquire snazzy new functionalities, improved throughput, perhaps some much-ballyhooed AI-driven capabilities (yes, I’m a bit dubious of that phrase.) But every so-called upgrade brings a truckload of potential problems.

Here’s why:

• Conflicting Rules: Upgrades are also a big time to change how rules operate—priorities, formatting, even defaults. You’d be surprised how many an “allow” rule, suddenly becomes a “deny” after an upgrade.
• Man in the Bird: New Credentials? Great. Misconfigured features? Not so great. I’ve seen VPNs fall apart, traffic slow up, entire chunks of a network become unreachable, all because someone overlooked a configuration during an upgrade.
• Old Rules: And do not forget about old rules—the dusty leftovers of past admin or past era in your network. Legacy rules get a bad habit of hanging around and breaking things in strange ways.
• Performance Issues: Yes, firewalls can just wake up and decide they’re running a marathon uphill with a backpack full of bricks. Upgrades can cause latency or even crashes entirely if your hardware isn’t first-rate.

The bottom line? They say an un-audited, post-upgrade firewall is a time bomb.

Our Audit Process

At PJ Networks, we like to think of post-upgrade firewall audits as an art form—and a science. All audits are thorough, detailed and designed to meet your unique environment. We do not believe in cookie-cutter approaches, because, well, your network is not a cookie.

Here’s how we do it:

1. Baseline Validation

• We discuss “baseline” before we even touch the upgraded firewall. How did your network function and behave pre-upgrade?
• We review logs for insight into typical traffic patterns.
• Existing Firewall Rules (Legacy junk)
• Find any services that must never go down, not even for a millisecond.

This baseline is our map. You wouldn’t do an engine swap on a car without knowing how it drove prior, would you? Same concept here.

2. Rule Set Review

• Sometimes upgrades jumble new rules sets or there are new things that might conflict with existing ones.
• Each rule is painstakingly analysed by our team. Line by line. Tedious? Sure. But it’s also the only way to make sure that critical traffic doesn’t get accidentally blocked.
• You want to find redundancy, because duplicate rules are not only annoying; they’re dangerous.
• Audit unused rules, log hits/misses, to clean up the clutter.

And here’s a fun one: During a firewall update for a bank, we discovered four rules which allowed unrestricted access to a mission-critical database server. FOUR.

3. Patch Management Check

One of the dirty little secrets about firewall upgrades? Many are shuttled out the door without proper testing. We verify that an upgrade doesn’t install new patches (and possibly new vulnerabilities). If we have to, we’ll scour vendor documentation and cut through the noise to speak to directly about it.

4. Performance Testing

Your network should be protected by firewalls—not slowed down to a crawl.

• Simulated Traffic: We stress test the upgraded firewall with generated traffic.
• Check CPU and memory usage (bottlenecks are cunning).
• Monitor latency, packet drops and throughput numbers against your baseline.

If something’s off? We investigate. No guesswork allowed.

5. Feature Validation

New features are great—unless they don’t work.

• If the upgrade has zero-trust updates, we check that segmentation and policies are applied correctly.
• If there is HA (High Availability), test fail-overs.
• Confirm that VPNs and other remote access methods are properly secured and functioning.

I just assisted three banks in migrating to a zero-trust architecture, and if you thought traditional firewalls were picky, zero-trust systems are downright persnickety.

6. Log and Alert Fine-Tuning

Seeing good logs is like finding buried treasure. Bad logs are noise. We adjust your logging and alerting configuration as follows:

• You receive alerts only when there are real threats (not every employee who mistyped their VPN password).
• When diagnosing future problems, correlating events is easy.

Quick Take

Short on time? Here’s the TL;DR:

• Firewall updates can result in rule conflicts, misconfigurations, and performance risks.
• A post-upgrade audit is crucial to identifying these problems before they result in breakage—or worse, create security vulnerabilities.
• At PJ Networks, our audit process encompasses:
• Realistic validation (know your network).
• Review the rule set (clean up the junk).
• Patch checking (I mean, is your upgrade even safe?).
• Testing for performance (firewall must be quick and secure).
• Functional stability (new features should not impair existing flows).
• Log with more signal, less noise.

Conclusion

Look, I get it. It’s an easy instinct to just roll out a firewall upgrade and keep your fingers crossed, (been there), particularly if your resources are tight. Of course, that’s easy to say—I’ve learned that over decades of networking in the ‘90s and operating a cybersecurity company in 2023: there’s great truth in the old cliché that an ounce of prevention is worth a pound of cure.

Firewalls are your first line of defense. If they’re not properly configured after an upgrade, you may as well throw open the front door and put up a neon sign that reads, “Hackers Welcome!”

That is just one reason why at PJ Networks, we don’t cut corners! So I’ve committed myself to make sure every one of the firewalls we interact with is rock solid, stable, and capable of defeating even the most advanced attacks. But let’s face it — cybersecurity is not about tools, it is about trust.

And if you don’t trust your firewalls, brother—I’m here to tell you—you’ve got a problem.

So before you do your next firewall upgrade, ask yourself: are you ready to audit it correctly? If not, give us a call. We’ve been at this for decades.” And we’re not going anywhere.

Until next time, stay secure. And have that post-upgrade audit done.

—Sanjay Seth
Cybersecurity Consultant
PJ Networks Pvt Ltd