Legal and Regulatory Notices (Terms of Service)

Okay, this is Sanjay Seth here: now I am sitting at my desk after my third coffee (yes, third…and no, I am not wired yet.) Played in this game of network and cybersecurity since the early 90s—started out as a network admin in the days when the PSTN mixed voice and data traffic on the same copper pairs. Remember those days? Each dial tone was a promise — a promise that data was somewhere safe. Spoiler alert — it didn’t work every time.

And you know what—those first days taught me a lot about what not to do with your firewall rules. Overly permissive rules — the classic Allow Any — have plagued secure networks for decades. Today, as I rewind the years I’ve spent running P J Networks Pvt Ltd, and helping businesses (including three banks recently upgrading their zero-trust architecture) in independent consulting, I’m finally writing this to tell you why your security vocabulary must have disappeared the words Allow Any from yesterday!

The Risks of Allow Any

I can see the poise here — when you are juggling a hundred firewall policies, it is easier to keep it simple: Allow Any across ports/networks gives you less trouble, fast setups right? But simple soon turns into dangerous.

Here’s a walk down memory lane — Slammer worm, anyone? This little beast came onto the scene in 2003, blasting through poorly filtered networks faster than most admins could utter Who opened that hole?. Excessively permissive firewalls were a gift. Having Allow Any rules is like opening your front door wide open and wishing the neighbors are friendly.

An overly permissive set of rules weakens your security posture — and introduces these huge blind spots. Attackers love these. They scan, they sniff, they creep in through every port or protocol you forgot to lock down. It’s kind of like giving away on-the-spot VIP passes to hackers — except that you don’t know who is and who isn’t VIP!

Allow Any — What Does It Actually Do?

• Allows all ports/protocols from a source (internal/external) to a destination
• Does not discriminate between good and bad traffic.
• Sprawls unexpected services and applications all over your internal network perimeter.
• Makes debugging effectively impossible — because once anything is broken, you have no idea where an attacker entered or how.

But — and this is key — some within the industry say it’s all right during initial rollouts or in very controlled settings. I disagree. If you have to use Allow Any in production, consider what exactly you are exposing. And if the answer is I don’t know—brace yourself.

Better Traffic Filtering

Traffic filtering is not simply a matter of checking boxes or ensuring default settings are active; it is your first line of defense. Because the devil’s always in the details, we spent countless hours at PJ Networks optimizing the firewall rules for strict security.

Firewall rules are like traffic lights on a busy road:

• Green indicates that traffic passes through freely, but it’s your call which vehicles get to cross.
• Red halts anything that isn’t permitted.
• And yellow? That’s where your monitoring and your alerts come in.

When you slam down an Allow Any, it is a little like turning every light green, every light flashing go go go — even if trucks full of toxic waste suddenly materialize. Chaos, no traffic control, make sense?

Instead, though — scope specific traffic filtering. Here’s how:

• Know the specific source and destination IPs that need to be able to talk.
• Restrict by protocol and ports to specific traffic — don’t enable the port for a protocol to only need HTTP.
• If it can be application- layer filtered, it should be — The more you know about what type of traffic is travelling through to help identify abnormalities.
• Never use default allows → default deny is your baseline, never default allows

It’s a little like cooking—you wouldn’t just dump every spice into a dish and expect it to be good, would you? Traffic filtering needs that same kind of judicious seasoning — too much openness and your network becomes a recipe for disaster.

Creating Specific Rules

Making rules laser-focused is much harder than it sounds (still working on my own rule sets here). This is your pass to freedom from lazy security.

Here’s my step-by-step:

1. Understand the needs of your business: Which apps need access? Which users? When is a data flow legitimate?
2. Segment your network: Split your network into components — banking servers, user workstations, administrative systems — and apply permissions to them accordingly.
3. Be as specific with rules as possible: Don’t write Allow TCP from anywhere to anywhere. Instead you say TCP from subnet A to server B port 443 only.
4. Use protocol whitelisting: Only allow protocols that are known, that you require (HTTP, HTTPS, DNS), block the rest.
5. Avoid any catch-all rules unless you absolutely have to have them—and if you must have a catch-all, be sure it’s recorded, reviewed and justified.

I will never forget one bank customer who accidentally created an Allow Any rule that applied to multiple internal VLANs. Guess what? Discover our rogue printing service out there, open to the internet—while, sure, it may be an old-school device from the 90s! That little mistake could’ve been worth millions to them—you know, data leaks, ransomware, pick your poison.

Implementing Least Privilege

A lot is said about the principle of least privilege, but few really apply it with the kind of rigor that it requires.

All of this begs the question — do you truly need to grant every system or user wide access because it’s easier? Nope. No, you don’t.

Least privilege means:

• Each user, device, and application is given only the access it needs to fulfill a role.
• This is reflected in firewall rules—no catch all allow rules.
• Do your best to limit lateral movement possibilities across your network.
• Augment with robust identity management and authentication.

I like to think of this as being like a car key system in a big office parking lot. You’re not giving away master keys to everyone—just the key to where he parks. Allow Any? That’s giving out keys to every car and every gate. Not smart.

Least privilege isn’t merely about security compliance or checkboxes. It’s about preventing problems at the outset. And yes, I know it can seem tedious to implement. But the payoff? A leaner, cleaner, a much more secure network.

Reviewing Rule Logs

This is where a lot of admins go off the rails—they enforce policies, then forget to verify that those policies are working.

We at P J Networks have a ritualistic approach to firewall rule reviews. You’d be surprised at what you find when you actually examine logs:

• Rules that are too permissive and survived earlier audits somehow.
• Unknown outside IPs attempting to hit your network.
• Rule-sets are overflowing with unused rules.
• Rules that no one can remember the reason for (a classic)

If you just don’t do it, you’re running blind. Logs are your insight into what your rules allowed and what they did not catch — and logs often tell the dirty truth about network security.

Pro tip: Automate where you can, but always take time to do manual reviews — no tool can catch all the nuance.

Quick Take

• Firewall rules should NEVER be Allow Any; this is a security disaster.
• Not surprisingly, specific, granular rules make your security posture many, many times stronger.
• Least privilege is your guiding light, not a slogan.
• Rule logs should be regularly reviewed to ensure continued cleanliness and security of the firewall environment.
• Imagine firewall rules as traffic lights—or spice in the food. You’re in control of the flow and the flavor — or you get chaos.

Conclusion

So do you actually want to bet your network security on sweeping Allow Any rules? Here’s the reality — if you do, you might as well walk out your front door and serve up your credentials on a silver platter.

Since then, and especially since I saw the Slammer worm up close and personal — watch it blitz a network through a small hole — I’ve become a bit evangelical about really tight firewall rules. My conviction is stronger than ever after three bank projects on zero trust that were all recent.

(Oh and speaking of hardware, just back from DefCon, the hackers’ convention, where I think we all came back from the hardware hacking village buzzing—those people have no mercy). They exploit every crack and crevice in your network’s armor. If you’ve got Allow Any rules hanging around on your firewall, then you’re basically begging them to come and suck all your fun away.

Final Thought

One more with your permission—p(w)ane(password 0) policies without strict firewalling policies? It’s like when you lock the front door, but leave the windows wide open. A facade of security is meaningless if the interior of your network is wide open.

Anyway, that’s enough of my caffeine-fueled soapboxing for today. A word to the wise — next time you want to slam down the Allow Any hammer, stop and think what you’re really risking?

Stay sharp. Stay secure.

Sanjay Seth
P J Networks Pvt Ltd