What is a Firewall in a Computer Network?

What is a Firewall in a Computer Network

What is a Firewall in a Computer Network?

Cyberattacks are increasingly prevalent. They come in various forms, as malicious intruders try to infiltrate organizations to steal data, disrupt networks, or make money by holding systems hostage. And this is yet another reason why network security for your organization or business is more important than ever! Malicious attackers usually try to attack institutions at their point of vulnerability, and their networks are often one of them. One reason is that wireless networks are notoriously prone to attack, and the radio frequency used by wireless networks to transmit data is often easily intercepted. Unsurprisingly, many organizations have responded with tighter security measures, including firewalls. But what exactly are firewalls, and how do they secure a computer network?

What is a Firewall?

The primary duty of a firewall is to serve as a barrier or blockade between a private internal network and public sources such as the internet. An efficient firewall will selectively allow or block access to the secure network; it will usually have a set of established security protocols to analyze incoming traffic coming from suspicious or unsecured sites before deciding which one to let in. The points where this information is exchanged are called ports or entry points.

Firewalls have had multiple definitions over the years, and one reason is that their operation mode has changed over time. Despite the consistent modifications made to them due to the constantly evolving cyberspace, firewalls remain a crucial part of network security. A firewall is a network security device that monitors and filters incoming and outgoing traffic in your network.

What is a Network Firewall?

With many organizations using private networks to send sensitive documents and information, there is an increased need to provide adequate security to protect those data. Network firewalls do an excellent job at these. 

Network firewalls are similar to typical firewalls but are specially designed to protect private networks. They are security devices that stop or restrict access to public sources to remote networks. Network firewalls act as liaisons between the devices in the private network and other external devices. 

Usually, firewalls are positioned at the front line of a network and configured so that any data entering or exiting the web has to go through it. If done correctly, the authorized users of the network can access every resource offered by the network while simultaneously keeping out unauthorized users, hackers, malicious programs, and viruses that try to invade the network. They are essential for networks prone to attack, such as wireless networks.

How Do Firewalls Work?

Firewalls remain an essential to improve cybersecurity for your business due to how they work. While anti-malware programs (such as antivirus) can help protect a system from suspicious software, they can still gain access to the system and move from one computer or another until they come across a vulnerable system. 

Firewalls do not allow malware or any other malicious software to gain access to your system in the first place. A good firewall monitors all network traffic and identifies and blocks unwanted traffic. They usually work with predetermined security protocols to filter out suspicious traffic and malicious traffic through various means.

Why are Firewalls Important?

Firewalls are crucial because they help monitor traffic flow in your network. Being able to track online traffic effectively has many benefits:

  • You can prevent virus attacks by controlling the entry points of your network. Viruses can shut down your digital business and steal sensitive information.
  • They protect you from hackers that hold your systems hostage or access relevant emails, customer data, etc.
  • Preserve the privacy and confidentiality of your organization and your client information; the firewall prevents spyware that can compromise that.
  • They give you control of your online and network security.

Types of Firewalls in a Computer Network

Network firewalls usually protect entire networks and are generally also called hardware firewalls. There are five main types of hardware firewalls:

1: Packet Filtering

Packets are small chunks of data within public traffic like the internet. Packet filtering firewalls with established security settings screen each packet for signs of predetermined red flags. If even a tiny part of the packet is suspicious, then the packet is blocked right away.

2: Proxy Service

A proxy service firewall acts as an intermediary between two endpoint systems. Information about all public sources is stored in a requesting system. Incoming traffic meets the firewall and is sent to the requesting system for verification, after which the firewall can either block or allow the traffic based on the result from the requesting system.

3: Stateful Inspection

Stateful Inspection is the most sophisticated and modern form of firewall. A vast trustworthy database holds all the significant attributes, such as each connection’s IP address and ports. During each session, the firewall compares all incoming traffic against the information in the database. If the comparison is favorable, the traffic is let through, but if it isn’t, it is automatically denied. This firewall is better because it is less memory-intensive and more efficient.

4: Circuit Level Firewalls

Circuit Level Firewalls protect a network by providing session-level control over network traffic. Although its operation method is similar to packet filtering, it generally works at a much higher level. They often act as relays between incoming packets and the host server and are often combined with other firewall types, such as proxy servers.

5: Next-Generation Firewalls (NGFW)

Next-generation firewalls are highly sophisticated firewalls designed to address advanced security threats at the application level. This type of firewall uses intelligent, context-aware security features that can better filter malicious software. In addition, NGFW has extra layers of protection not commonly found in other types of traditional firewalls.

How Does a Firewall Protect Data?

Firewalls protect data in your private network by managing network traffic; this includes monitoring and accessing incoming and outgoing traffic and blocking suspicious or malicious malware. 

A firewall will often use any of the five processes explained earlier to do its job effectively. Data is often lost or held hostage when malware, viruses, or hackers access the network or an individual system. Firewalls make this extremely difficult by blocking access to private networks using susceptible filters. 

These filters can be software-based; they are found in the computer and monitor all traffic on that computer. They can also be hardware-based, located between the internet and the computer. For example, most routers used for wireless networks often come with firewalls that monitor and filter traffic for everybody using the router. A firewall is a good start to deter cyber security threats from small business all the way up to enterprise businesses. If you are an enterprise business and are only running a firewall in your security stack you may need to take a look at this article -> How Do I Choose A Managed Service Provider. 

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Importance of Firewall in Network Security 

Many networks, especially wireless networks, often lack security and are consequently vulnerable to attack. Many users are at risk of data and identity theft, hacking, and online fraud. Firewalls protect against these threats and allow users to surf the internet safely.

Unlike antiviruses that offer only limited security to a single system, a firewall can protect an entire network by filtering out malware and other harmful traffic, preventing damage or other forms of attack from cybercriminals on the prowl, and looking for vulnerable networks.

Why Your Company Needs Website Firewall Protection

There are several reasons why your company will need website firewall protection. If your company uses a wireless network, it would need one as these networks tend to be vulnerable and prone to interference. If your company does a lot of work online, they are especially exposed to cybercrimes and need protection.

Suppose you deal with the public and store client or customer data online or in a system. In that case, the best practice will be installing a firewall to protect your network from data theft and ransomware that would hold your information hostage.


Firewalls are essential to network security as they shield your network from malicious software and viruses that seek to steal or destroy data. There are different firewalls, but they can be either software-based or hardware-based (like routers). If your company’s work is majorly online and you are wondering how to secure your wireless network, consider investing in a sound firewall program to protect your business. Computronix team is available for all of your IT Support and Cyber Security needs. Contact soon.