7 Types of Firewalls and Main Facts About Them

Firewalls Types
Source: unsplash
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Security of network connection is one of the most important things to keep an eye on in the business. If your company’s equipment isn’t protected, it can be easily accessed from any computer in the world with just a few tools and a bit of knowledge. So, you need some kind of a guardian that will ensure that the connection is safe.

That’s why firewalls exist. They are devices or programs that block harmful network packages, thus not allowing them to get into the computer. However, while there are many types of firewalls of different forms and specifics, it’s important to know which of the following is a firewall function:

  • Establishing a secure connection through a network of remote servers located in a different country.
  • Establishing a connection through a single remote server.
  • Finding and destroying viruses and other forms of malware.
  • Securing the connection by filtering the packages and blocking harmful data.

Only the last one is the function of the firewall. The first two functions are performed by VPN and proxy respectively. The third one is done by antiviruses. Right, they do protect the computer, but in a different way.

Nowadays, most devices have in-built firewalls. Not literally of course, but they are implemented into an OS by the developers. Yet, as you could guess, those aren’t always as reliable as you would want them to be. So, it’s important to be able to recognize when your security level is too low and install a new defense.

We asked professionals from Develux to provide us with valuable insights on the best firewalls and the differences between them. Here’s the list of the main types of firewalls.

1. Packet-Filtering

As the name suggests, these firewalls filter the network packages your computer receives. They analyze all the incoming data and only allow the packages they find not harmful. Some of these systems have very good detection protocols and work flawlessly, while others can’t detect hidden malware but block unharmful data.

However, the packages themselves do not get opened. Such systems have a set of rules that determine whether the data is allowed or not, and if those rules aren’t met, the packages are simply denied access. There are 2 sub-types of packet-filtering protection: stateful and stateless.

The first one analyzes the incoming packages as a sequence, taking all the previously analyzed ones into consideration. The latter views each package separately, analyzing it individually.

This type offers only a very basic level of protection and can be easily tricked. Yet, its main advantages are the low impact on system performance and the fact that it comes pre-installed on most platforms. The latter makes this type of firewall the most popular and probably the best one for home overall.

2. Proxy (Application-Level, Cloud)

Proxy firewalls, not to be confused with proxy servers, filter the incoming data on the level of application. They’re called proxy or cloud firewalls because such defense is usually installed on a separate device. It connects to your device first and then filters the packages.

Most of the time, they work similarly to the stateful packet-filtering systems, with the addition of TCP checks. However, some more advanced proxies may even open packages to analyze the contents and determine whether it’s harmful to the system. After the data is checked, the proxy sends it to the computer.

You can think of proxy firewalls as a kind of gate that is located outside of the house but still determines whether anyone is allowed to enter. The main advantage is the space between the gate and house, which provides an additional security layer. But of course, this space also means that the data reaches its destination much slower.

3. Circuit-Level

Circuit-level protection analyzes incoming traffic by checking its TCP handshake (Transmission Control Protocol). The data only passes if its TCP exists and is legitimate. This is a very simple process, thus making this type impact the performance of the system only a tiny bit.

However, it only checks up on a single factor – TCP. The content of the packages is never touched. That means that harmful packages can easily bypass the firewall if they have the right TCP.

4. Network Address Translation

While NAT itself isn’t a firewall, many defensive systems use it to give devices inside the network particular names. They can only be recognized by the devices inside them and the protection itself, which makes connecting to them without knowing NAT names impossible.

How does having a name protect the system? As we all know, to establish a connection between 2 computers, they need to know each other’s IP. Of course, most modern software does everything automatically, but the basics still remain the same. By hiding the IP behind a name, such defensive software simply hides the potential targets.

NAT Firewall Types
Source: unsplash

5. Web Application

This type only targets the traffic received by visiting websites or using web applications. It works similarly to proxy type but focuses on filtering web packages more. It can be located on cloud or proxy servers. In most cases, web application firewalls are used for server protection or as additional layers of defense.


NGFW stands for Next-Generation FireWalls and is a pretty broad term. The name “next-gen” was given when they only started to appear on the market, but today it’s the most commonly used type. All the detection protocols, the optimization and the security itself suit modern standards.

Why is it a separate category? Well, computers have evolved a lot in the last 30 years. New processors are presented every 1-2 years. All of that means that the systems gain a lot of power very fast. What was impressive 5 years ago is considered “not enough” today.

So, next-gen firewalls are made to utilize all the advantages of modern systems, without damaging the performance. They also make use of all the modern security protocols, antiviruses, intrusion detection, and basically any features that provide extra protection.

The main drawback of NGFW is the lack of particular classification for them. It’s just a name for all the protective systems that were released recently, and it doesn’t explain how it works and what it focuses on. It’s recommended to analyze and find feedback on every particular firewall of this category individually.

7. Hardware

As sort of the opposite to NGFW, hardware firewalls are mainly regarded as a thing of the past. They are located in separate cards that are installed in PCI-X slots. It was a very common thing for computer vendors to pre-install them as an additional feature.

But of course, they are present today too. Think of hardware firewalls as an additional router inside your system that filters all the incoming traffic. The main advantage is a very high level of protection and resource efficiency. Yet, they are very vulnerable to attacks from the inside. So, if any malware manages to get into the system from other sources (flash drives, for example), the protection can be easily shut down.

Wrapping It Up

Some of the types presented in the list have different specifics and focus on different aspects of connection security. But they all have one thing in common – they filter the incoming data and only allow the safe packages based on particular requirements, be it TCP or package contents. So, analyze your demands and system capabilities to choose the right one, and may your device always remain safe from attacks.

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Paschal Okafor is NaijaTechGuide Team Lead. The article 7 Types of Firewalls and Main Facts About Them was written by NaijaTechGuide Team. The article was last modified: June 4th, 2022
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