Firewall Logs and Compliance: Essential Guide for Network Security

Ok, grab your third cup of coffee (or maybe that’s just me) and let’s take a look at one of the topics that keeps security folks like me up late at night – firewall logs and compliance. For those of you that don’t know me, back in the early ‘90s I was a network admin in the trenches and I mean everything from PSTN multiplexing right through to some of the nastiest such as Slammer. Twenty years later, I run P J Networks where, among other things, I show banks how to upgrade zero trust with the confidence logs won’t just sit collecting dust. Just returned from DefCon’s hardware hacking village, still stoked and geekin on that stuff.

Why Firewall Logs Matter

Firewall logs — they’re the black box of your network. When things go sideways (and they will), these logs are what let you know what really happened. But here’s the thing — well, two things — maintaining these logs is not just a security function, but also a compliance function. And man, if you’re cutting corners in this realm, you’re setting yourself up for a world of hurt.

Log Retention Policies

Your eyes may glaze over when you read “log retention” — I’ve been there. But knowing and creating a functional log retention policy is the foundation of good security hygiene and compliance. I’ve seen organizations spend months trying to gather logs only to dump them before the audit begins. Here’s what I always say:

• Specify what logs to retain specifically – firewall logs, application logs, system events, etc.
• Determine how long to store the data based on your industry and risk profile — work with the presumption of nothing one-size-fits-all.
• Think about how big things might get, space-wise — logs can grow long and dense, not unlike that enigmatic pasta sauce recipe that just keeps going and going.
• And real deletion policy (if you are doing all the above) no clutter, no overexposing.

Way back in my youth, logs were kept on punch cards (yes, really!). Now? We are processing terabytes of data every single day. It’s tempting to save everything — but that’s a mistake. Keeping more than you need not only wastes space, but also increases your attack surface. Someone breaks in and there are years’ worth of logs — that’s a goldmine for bad actors.

Industry Compliance Requirements

This portion can be like walking blindfolded in a labyrinth. Different industries need different things. Trust me — from having helped three banks rearchitect their zero-trust recently — compliance isn’t a freaking checkbox; it’s a living, breathing process.

PCI DSS requires to keep firewall logs for at least a year and to be able to quickly access the latest 3 months for review. GDPR? That throws a curve with privacy concerns around data — retaining must be defensible and minimal. In healthcare, HIPAA requires that logs be kept for the protection of patient privacy, but they need to be kept secure.

Now, some people get stuck on compliance equals security. Not entirely true. Compliance is the bottom line, not a golden ticket. Certain companies, sure, they comply with PCI DSS but yet still suck at real-time monitoring. Logs are only as good as when you end up looking at them — your SIEM must do all the heavy lifting here.

So tip: Know the regulations like the back of your hand. This isn’t one-size-fits-all advice, and neither should your retention policies be — don’t just copy some template off the internet and call it good.

Storage Best Practices for Logs

Log storage deserves more consideration than just throwing logs in your server or cloud bucket. I’m a little old-school in this — I remember when we had no cloud and every GB was gold. Now with cheap cloud offerings people just dump everything — often without encrypting it.

Here’s what I suggest:

• Store your logs in a secure, dedicated place.
• Encrypt in transit and at rest — don’t give anyone carte blanche on your data.
• Set access controls — logs should be read-only to the majority of users.
• Store older logs on cheaper media, but maintain them so they are still available for audits.

Quick rant: I’ve also seen sysadmins treat log storage as a junk drawer. No index, no access control, and don’t even think of backups. That is akin to hiding your car keys under the doormat and praying they will not be found.

Secure Log Archiving

Logs are more than just data to be saved — they must be a reliable account. So integrity is king. How do you verify logs haven’t been tampered with? This is where things like digital signatures and hash chains and write-once media come in.

At P J Networks we implemented solutions whereby logs are timed and hashed the instant they are made. This way, if anyone attempts to change logs post-hoc you find out right away. And in spaces like banking — where dozens of compliance bodies might audit you — that’s not optional.

Also — think about more than how to keep them compliant. Some logs could also be required down the line for forensic audits. Don’t cut corners here.

Automating Compliance Checks

Here is the multimillion-dollar question: How do you make all of this happen day in and day out without your security team turning into zombies? Automation is the answer.

• Feed your firewall logs into a SIEM (Security Information and Event Management) system.
• Set up automatic alerts for log anomalies or lack of log activity.
• Automate reports which highlight retention non-compliance.
• Utilize scripts or tools to implement the retention policy and archive or destroy logs as appropriate.

Here’s the catch: Tools are not magic. And I’ve witnessed shops invest in AI-powered security services without the first idea about what’s actually inside this can of worms. If you can’t tell me how your system is analyzing the data — be afraid. Good rule of thumb: Automation should aid not replace a strong security posture.

Quick Takeaways for Effective Log Management

• Make a clear definition of a retention policy. Be specific.
• Understand your industry compliance — PCI DSS for payments, GDPR for EU data, HIPAA for health.
• Secure logs: Encrypt, restrict access to, and backup logs.
• Hash or digital sign logs to guarantee the integrity of the logs.
• Automate the grunt work with your SIEM — but don’t rely blindly on AI.

Conclusion: The Importance of Proper Log Retention

Rounding up — how is it possible that so many companies still have so much trouble retaining and being compliant for logging? Because it’s a pain. Logs are big, loud, lumbering, and go on forever. But for all that, remember, that behind every successful breach investigation or compliance audit is a good set of logs. And managing them well? That’s cybersecurity 101.

If you’re the sys admin type, running networks, firewalls, or servers (and you know who you are, business owner), don’t neglect your log retention. It’s not just a technical checklist, it’s your story — written in ones and zeroes — about how well you looked after your own back.

On a personal note — I also completely butchered my first-ever log retention setup in the 90s. Lost some important logs because I didn’t create a deletion policy. Learned the hard way. Today, we at P J Networks are in the business of keeping you from making the same rookie mistakes I did.

Stay vigilant, stay compliant — and hey, maybe brew another coffee. It’s always a few more firewalls to configure.

Cheers,
Sanjay Seth

P J Networks Pvt Ltd
Security Consultant since 2000,
Network Admin since 1993