Exploring the 5 Most Common Firewall Architectures

If you’re setting up or managing a network, keeping your data secure needs to be priority number one these days. And given how much threats have evolved over the past few years, this is certainly becoming an increasingly difficult task. No pressure then!

Well, the good news is one of the best tools at your disposal for locking your network down is a reliable firewall. But here’s the thing — firewalls come in a variety of different shapes, sizes, and flavours. As such, each firewall architecture has its own pros, cons, and ideal uses.

So when you’re shopping around for the perfect firewall fit, it helps to do a little homework to understand what sets each type apart (and which one suits your business best).

In this guide, we will walk you through the five of the most popular firewall architectures being used today, giving you a simple breakdown of how each one works behind the scenes, including the core strengths and typical use cases where each firewall shines brightest.

Packet Filtering Firewalls

The packet filtering firewall is the simplest and most basic architecture out there. As packets enter the network, the firewall analyses and filters them based on a set of predefined rules—hence the name. Here’s a quick rundown of what packet filtering firewalls have to offer:

• Lightning fast performance – Since filtering decisions are made at the network layer, packet inspection is extremely rapid. These firewalls can handle heavy network loads better than more advanced models.
• Operating system agnostic – Packet filters aren’t built into a specific OS, so they work across platforms.
• Limited functionality – While speedy and versatile, packet filtering firewalls have fewer features than application-level or proxy firewalls. Their rules tend to be less sophisticated.

If you have a basic network with minimal security requirements, a packet filtering firewall may fit the bill. They also work well in hybrid arrangements, handling initial network traffic before passing certain packets up to a more robust firewall.

Stateful Inspection Firewalls

Stateful inspection firewalls add context to the filtering process by monitoring communication sessions instead of inspecting packets individually. They keep track of the state of sessions and only allow packets that align with legitimate, established connections.

Here are some of the highlights of what stateful firewalls bring to the table:

• Understands packet context – By tracing connections, stateful firewalls can identify and stop threats that evade basic static rules. This makes them far more secure than packet filters.
• Built-in network address translation (NAT) – Stateful inspection firewalls automatically translate internal IP addresses to external public IPs. This adds an extra layer of internal network concealment.
• High performance capacities – Stateful firewalls work almost as rapidly as packet filters. Although they’re slower, they can still handle heavy loads.
• No need to configure inbound/outbound rules – You simply define policies for general use cases rather than specify inbound vs. outbound traffic rules. This saves admins lots of time and hassle.

If you need a balance of strong security, flexible policies, and reliable performance, a stateful firewall may be up your alley. Many networks rely on stateful models to deliver robust protection without compromising speed or connectivity.

Next-Generation Firewalls (NGFWs)

As the name suggests, NGFWs represent the very pinnacle of firewall engineering. These systems integrate all the features you’d expect from traditional stateful firewalls while adding advanced capabilities for threat detection and prevention. Here are some of the main NGFW features and perks that these cutting edge solutions provide.

• Intrusion prevention – NGFWs combine IPS functionality into the firewall, scanning traffic for malware payloads and suspicious activity and terminating sessions that pose a threat.
• Application awareness – By performing deep packet inspection, NGFWs understand applications and protocols and can implement granular app-specific rules.
• Built-in VPN capabilities – Many leading NGFWs include site-to-site VPN functionality for secure remote access without needing additional VPN software or hardware.
• Cloud delivery options – Several vendors offer NGFWs in cloud-based or hybrid deployment models in their product lines.

While NGFWs are pricey, their cutting-edge feature sets justify the premium for organisations that demand robust, proactive defences across the threat landscape. If your infrastructure faces elevated risk, NGFWs deliver unparalleled protection.

Web Application Firewalls (WAFs)

Whether it’s online banking portals or the vast array of eCommerce storefronts, web applications have become an absolute key component of the internet that we all know and love (mostly). However, as much convenience that these interfaces bring, they have also become a crown jewels for hackers. Unlike earlier firewalls, WAFs focus specifically on defending external-facing web applications from attacks. These are a few areas where WAFs shine:

• OWASP Top 10 protections – WAFs are tailored to mitigate common web app vulnerabilities like code injection, broken authentication, and misconfigurations as outlined in the OWASP Top 10 standard.
• Compliance mandates – Many WAFs help companies achieve compliance with regulations like PCI DSS for payment card security.
• AI and machine learning – Leading WAFs integrate artificial intelligence to learn application behaviour and distinguish between legitimate traffic and sophisticated web assaults automatically.
• API security – Some WAFs safeguard REST API interfaces in addition to standard web apps.

If your infrastructure relies heavily on web-based apps, adding a WAF can drastically improve your security posture against web attacks. They provide specialised protections regular firewalls simply don’t offer.

Software-Defined Perimeter Firewalls

Last but not least, software-defined perimeter (SDP) firewalls take a radical approach to network security. SDP architectures create cryptographically verified, identity-based perimeters around protected resources. No packet can penetrate that perimeter without explicit authorisation. Here’s an overview of why organisations deploy SDP firewalls:

• Zero trust framework – SDP aligns perfectly with zero trust strategies, only granting least privilege access on a strict need-to-know basis after validating identities.
• Obfuscates network topology – SDP solutions conceal private IP addresses and infrastructure, presenting an empty network facade to unauthorised users.
• Agent-based architecture – Lightweight agents verify identities on hosts/VMs before allowing dynamic, controlled access through the SDP perimeter to specified connectivity.
• User-oriented model – SDP focuses on identity and role-driven policies for users over traditional IP-centric rules.

For extremely high-value networks dealing with sensitive data or elevated threats, an SDP firewall may provide the perfect balance of watertight security and granular access control.

Final Word

Packet filtering, stateful inspection, next-gen, web app, cloud – there’s definitely no shortage of options to think about when it comes to choosing a firewall.

At the end of the day, you have got to match firewall solutions to your own risk tolerance, traffic volumes, infrastructure, and business priorities. Each environment is unique. By understanding the core strengths and weaknesses of these different models, you can zero in on the right technologies for your organisation’s needs.

So give these firewall types a close look, analyse where they overlap and diverge, and map out what combination makes sense for your defences. Your network will be safer for it.