What Is a Firewall and Does Your Business Need One?

When people talk about IT security in a business, one of the first words that comes up is firewall. Yet many business owners are not sure what a firewall actually does, how it differs from antivirus software or the router they already have, and whether a small business or factory really needs one.

This guide explains it in plain terms: what a firewall is, how it works, the main types, and the steps to deploy one in an organisation, so you can judge where your own network should start. If you would like a team to design and install it for you, see our business firewall installation service.

What Is a Firewall?

A firewall is a system that controls traffic between networks according to a set of rules. Think of it as the security guard at the company gate: everyone coming in or going out is checked, and only those who meet the conditions are allowed through.

In practice, a firewall usually sits between the internal network (LAN) and the internet. It can also separate internal networks from each other, for example keeping the accounts department apart from guest WiFi, or factory machine networks apart from office networks.

A firewall does not replace antivirus. Antivirus protects individual computers, while a firewall controls traffic at the network level. The two work together.

How Firewalls Work: The Main Types

Firewalls have evolved over several generations, and each type inspects traffic in more depth:

• Packet filtering: checks each packet’s source and destination IP address, port and protocol against the rules. It is the most basic type: fast, but unaware of the context of a connection.
• Stateful inspection: keeps track of each connection, so it knows whether incoming traffic is a reply to a connection that an internal device opened. This is safer than checking packets one by one.
• Proxy / application gateway: acts as an intermediary that sends and receives traffic on behalf of the device. It can inspect traffic down to the application level but needs more resources.
• Next-generation firewall (NGFW) and UTM: combine many functions in one device, such as application control, intrusion prevention (IPS), web filtering, antivirus and malware scanning, VPN, and inspection of SSL-encrypted traffic where configured. Devices such as FortiGate belong to this group.

Hardware vs Software Firewalls

A software firewall is a program running on each computer, such as the firewall built into the operating system. It protects only that machine and works best as an extra layer.

A hardware firewall is a dedicated device at the edge of the network that protects every device behind it at once. Policies are managed in one place, and it supports business features such as VPNs for linking branches or remote staff, network zoning and logging.

For businesses with several users, servers or multiple sites, the usual approach is a hardware firewall at the edge plus software firewalls on the computers.

Signs Your Business Needs a Firewall

• You rely on the router your internet provider installed, and nobody manages its security settings.
• Servers, shared files, accounting software or customer databases sit on the network.
• Staff need remote access, or several branches must connect to each other.
• Guest or customer WiFi shares the same network as staff.
• CCTV cameras, machines or IoT devices are connected to the network.
• You want to control or restrict websites and applications during working hours.
• You need to keep network usage logs for later review.

If several of these apply, a properly planned firewall will reduce your risk considerably, especially combined with network segmentation using a VLAN. For factories, see our overview of factory security systems.

Steps to Deploy a Firewall in an Organisation

Deploying a firewall does not start with plugging in a box. It starts with understanding the organisation’s risks and needs. A typical sequence is:

1. Analyse risks and identify problems. The most important first step: what data and systems need protecting, who uses them from where, and what problems you face today.
2. Define a security policy. Decide what is allowed and what is not, for example who may access the server and that guests get internet access only.
3. Define user groups and administrators. Group users by department or access level, and decide who is responsible for managing the firewall.
4. Design the network structure. Create zones such as office LAN, servers, guest WiFi and CCTV, and choose a model that handles your number of users and internet speed.
5. Write rule sets from the policy. Apply least privilege and block everything that is not explicitly allowed.
6. Install and test. Install the device, configure VPN and security features, and check that day-to-day work is not disrupted.
7. Monitor, maintain and review. Enable logging, update firmware and threat databases, back up the configuration, and review the rules as the organisation changes.

Example Firewall Devices for Businesses

There are many NGFW brands. One widely used range for small and mid-sized organisations is Fortinet FortiGate, which comes in several models for different sizes and traffic levels, for example the FortiGate 60F and FortiGate 100F. Choose a model based on the number of users, internet speed, the features you plan to enable and future growth, because deep inspection features use more of the device’s capacity.

Beyond the hardware, consider licences for security features and updates, as well as ongoing maintenance. These matter as much for long-term security as the model you choose.

FAQ

What is the difference between a firewall and antivirus?

Antivirus protects individual computers, while a firewall controls traffic at the network level. Businesses should use both.

My router already has a firewall. Do I need another one?

Typical routers offer basic functions such as NAT and simple packet filtering, but usually lack IPS, application control, web filtering or usage reports. If you handle important data or have many users, consider a dedicated firewall.

What is the first step in deploying a firewall?

Analysing the organisation’s risks and identifying problems, before defining the policy, user groups and firewall rules.

Is a UTM different from an NGFW?

Both describe devices that combine several security functions in one box. UTM is often used for small and mid-sized business devices, while NGFW emphasises application-level inspection and control. Many current devices do both.

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