A Beginner’s Guide to Firewalls for Business

Updated: April 29th, 2024

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What are Firewalls and Why are They Important For Your Business?

With a staggering 7.78 million cyber crimes taking place in the UK alone between late 2023 and early 2024, according to data from the UK Government, the need for effective defence against cyber threats has never been so prominent. Firewalls are a key element used by both individuals and businesses to protect themselves – and their private data – from hackers and web-based threats. 

Businesses that do fall victim to a cyber attack, experience a ripple effect that may cost them financially in the short term, whereas the long-term effects of the attack may force them to close their doors entirely. In other words, if you run a successful business and you don’t have a strict security policy in place with the right tools, you’re taking the biggest of risks.

Firewalls are a key element used by both individuals and businesses to protect themselves, and their private data, from hackers and web-based threats. With the global firewall market expected to double in size several times between now and 2030, according to data from Grand View Research, it’s clear that firewalls are seen by many as one of the most essential forms of threat protection and a serious line of defence against ever-evolving network breach methods.

But what exactly is a firewall, how do firewalls work, and how do businesses choose the right firewalls for their exact circumstances? Keep reading to find out everything you need to know about Firewalls for your business.

What is a Firewall?

A firewall is a piece of technology that analyses incoming and outgoing traffic in your network performing controlled access measures. It allows non-threatening traffic to pass and prevents unauthorised traffic from the internet from gaining access, stopping malicious network traffic from infecting your devices or network environments and stealing sensitive data. The best way to explain what a firewall is and how it works is to think of a real-life physical firewall; this is where the term ‘firewalls’ comes from when we’re discussing networks. 

Firewalls, in a fire safety sense, are structures within buildings to prevent fires from spreading and causing further damage. A fire will spread until it hits the firewall, which is robust enough to stop the fire dead in its tracks, essentially saving the rest of the building from certain doom, just as cyber security firewalls prevent unauthorised access to your network and devices.

Another way to think of it is to imagine a simple fish tank filter; water (network traffic) is sucked into the filter (firewall) where all the gunk and messy elements of the water (dangerous traffic) are trapped in the filter before the cleanest and purest water (authorised traffic) can pass through the pipes back into the tank (your network and devices). Easy, right?

What Types of Firewalls Are There?

Network firewalls can be pieces of software or physical hardware. Software firewalls can be installed on a per-device basis, ensuring every device in a business has at least some defence against security threats. When a connection reaches a device, it is scanned by the software and either allowed to make the intended connection or discarded. Most anti-virus software includes some form of firewall, and Windows machines often come with very basic built-in firewalls, though these aren’t always rugged enough for the needs of most modern-day businesses, which is why choosing a dedicated firewall provider is often best.

Firewall hardware, on the other hand, receives incoming connections from the internet and scans them before they have the chance to reach the wider network and devices, adding yet another line of defence against potential threats. Businesses are often advised to install both, to offer multiple layers of protection. If an infection can break through one firewall, there’s every chance it could still be caught by the other.

Firewalls are also available in a cloud-based format. These firewalls are hosted off-site but still monitor all the traffic flowing to your network and devices. Cloud-based firewalls are useful for companies that want to reserve as much memory as possible on their devices or don’t want to install any more hardware on their premises. On top of this, firewalls hosted in the cloud by a third-party provider are regularly monitored and updated, ensuring a business benefits from only the top line of defence, cutting the chances of a hacker or malware gaining entry to the network.

How Do Firewalls Work?

Like all machines, firewalls are programmed to follow a predetermined set of “rules” to protect your network and devices from infection. Firewall rules are either set by the firewall as standard, directed by the network administrator or are learned behaviours picked up by the firewall as it carries out its function – this is known as “machine learning” and is a feature in several next-generation firewalls.

Firewalls analyse incoming traffic and first determine its type, to decide whether or not to allow it to pass, block it entirely, or if it requires further investigation. A few of the elements firewalls examine are:

  • The source: Where did the connection come from?
  • The final destination: Where is the connection trying to get to?
  • The contents: What is the connection trying to deliver?
  • The language: What ‘language’ or form does a connection take?

While contents and languages of delivered connections can be discarded or allowed to pass with relative ease (these are the most obvious to spot) when it comes to sources and final destinations, firewalls will either grant or deny entry based on IP addresses and ports. You’ve likely heard of IP (Internet Protocol) addresses, these are identifiers given to devices and, when looked at in-depth, can be used to trace the location of a specific device. Ports, on the other hand, can be thought of as a more specific identifier than IP addresses, to determine where a connection is coming from. Think of them as specific, real-life addresses you’d write on a package – if you were merely trying to deliver a package to an office building, you’d write the name of the building (IP address). But if you wanted to reach a specific company in that building, you’d need to write the name of the company (ports).

What Do Firewalls Protect Against?

Firewalls are designed to protect against many different refined threats, but here is a quick summary of the key types of threats firewalls can repel:


The thought of someone putting a lot of time and effort into hacking your business network can be a scary thought. While some people like to think the scariest hackers only exist in the movies, nothing could be further from the truth. You hear stories in the news all the time about major businesses suffering breaches. A lot of the time, this is not the result of a virus that has been unleashed on the internet and left to cause its own chaos; rather, these are the results of countless hours of malicious activity by cyber criminals to spot weaknesses in network security and find a way through.

Firewalls protect against hackers by analysing incoming network traffic to determine precisely where a connection is coming from and what it is trying to do. If the firewalls spot a connection from a hacker and identify a threat in what they are trying to force into the network, they will put a stop to it immediately and alert the relevant person in the business (often an IT manager).


Malware is the umbrella term used to define a wide range of software that has been designed to infiltrate or damage a network while gaining access to sensitive data. Malware is usually unintentionally downloaded to a device when a user clicks a link or pop-up (if web filtering hasn’t caught it first) disguised as something else, or downloads a piece of software they believe to be legitimate.

Computer viruses are one of the most common forms of malware, spreading from one part of a device to the other, or to multiple devices on the same network. From here, viruses can make significant changes to the underlying structure of a device or network without the user’s authority. Here are just some of the other ways viruses and malware can be harmful to your business:

  • Download sensitive data and deliver it to the creator of the virus
  • Track keystrokes, microphones, webcams and more (Spyware)
  • Encrypt all files and demand payment before they can be “unlocked” (Ransomware)

Thankfully, advanced firewalls can stop many of these threats from accessing the network and devices by analysing them on arrival and quickly deciphering the type of connection they are, before blocking them completely.

Unnecessary Traffic

As worrisome as all of the above sounds, sometimes firewalls can be put to use to deal with less threatening arrivals. It can simply be the case that unnecessary traffic tries to find its way to a business network and devices, for countless reasons. But businesses need to focus on fully utilising their network, ensuring it doesn’t become clogged with non-essential connections, slowing down processes across the board. That’s when firewalls can kick in and deem certain connections as ‘vital’ and ‘non-vital’. In other words, any connections that don’t aid your processes in some way will get the boot, so you can make the most use of the traffic you actually need.

Why Should Businesses Use Firewalls?

Protect Data and Devices

Large businesses deal with excessive amounts of data every day in the digital age, much of which is very sensitive and could be disastrous should it fall into the wrong hands. Firewalls as a major component of protecting company data, ensuring hackers and malware are unable to gain access to certain devices or the wider system, to steal said data. Without an effective firewall and other protective measures in place, businesses are placing their data – and their future – at risk at any given hour of the day. 

The same is true for the safety of the devices themselves. Once a device has become infected, it can be damaged from the inside and rendered completely useless, depending on the directive of that which has gained unauthorised access. In this case, businesses stand to lose thousands in repair or replacement costs.

Avoid Downtime

If there is no effective firewall in place and someone or something can breach a business’s network, the downtime that this would cause could be fatal. Even large businesses with plenty of financial backing can experience severe downtime as the damage is repaired and data is (hopefully) restored, with many having to deal with days or even weeks with no progress whatsoever. 

Legal Requirements

Given the level of trust that is placed in modern businesses to protect data and use it wisely with a conscience at heart, it is understandable that the protection of this data isn’t a voluntary choice, it’s a legal obligation. Businesses are required to have strict security policies in place (such as firewalls) to ensure everything that could be done to defend data is being done. In the event of a breach, and a follow-up investigation finds a business’s cyber security practices seriously lacking, or showing a blatant disregard for company and customer data, there could be severe penalties including hefty fines and, in some instances, jail time. All of this makes using an effective firewall a no-brainer.

Want to Know Which Firewalls are Right for Your Business? Speak to Netcentrix

As business IT specialists with decades of combined experience delivering the tools and technology businesses need to protect themselves, Netcentrix is here to deliver the firewall solutions you require to put your data – and your peace of mind – first. We can analyse your business and your daily processes to recommend the best firewalls to suit your needs, thanks to our partnerships with some of the industry’s leading cyber security providers.

Our proactive support means you won’t need to report issues to us every time something rears its head. Chances are we’re already taking care of it, so you can spend more time focusing on important tasks and driving the business forward. Plus, should any issues arise, you’ll be assigned a dedicated account manager to deal with this for you, so you’ll always have someone to contact in your hour of need.

Speak to our Netcentrix experts today.


  • Liv Appleton

    Technology Content Marketing Executive, Liv, joined the team in 2021, as our technology copywriter, before progressing to her current role as our Content Marketing Executive in 2022. Liv has a strong background in the field of technology and leverages deep industry knowledge across a range of topics to create informative, insightful, and educational content to guide businesses towards effective technology adoption. Liv is committed to bringing up to date information on the latest technology, reporting on industry trends and providing advice to empower customers to make the most of everything their technology solutions have to offer.

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