What does a Firewall do? Understand the Basics & Benefits

By Tibor Moes / Updated: June 2023

What does a Firewall do? Understand the Basics & Benefits

What does a Firewall do?

Imagine your computer network as a castle under constant siege from online threats. Firewalls act as sturdy walls and moats, defending your precious data and resources from cybercriminals. As the digital landscape evolves, so does the complexity and variety of cyberattacks.

In this blog post, we’ll dive into the world of firewalls, exploring their foundations, types, best practices, and emerging trends to help you fortify your network and stay ahead of the curve.


  • Firewall protect a network from malicious activity by filtering incoming and outgoing traffic according to security rules.
  • They provide a layer of security for networks by monitoring traffic and restricting access to unauthorized users or activities.
  • There are many types of firewalls, each offering specific benefits and features, such as packet filtering, stateful inspection, and more.

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Firewalls: The Foundation of Network Security

A firewall is like the castle’s vigilant guard, guarding your network against malicious invaders by monitoring incoming and outgoing traffic. Acting as a crucial network security device, a firewall filters traffic within a private network, allowing or blocking it based on a set of predetermined rules. This ensures that nothing malicious slips through, keeping your private data and resources safe from cyberattacks.

Firewalls are essential for both corporate and consumer networks, working hand-in-hand with antivirus applications to provide a comprehensive defense against online threats. By monitoring and filtering all network traffic, from outgoing to application-layer traffic, firewalls help maintain the security and integrity of your network.

How Firewalls Monitor Traffic

Firewalls function by examining data packets at different network levels, using a set of rules to determine whether traffic should be allowed or blocked. These rules take into account factors like the source, destination, and content of the packet data. Various types of firewalls, such as packet filtering, stateful inspection, and proxy firewalls, monitor traffic in different ways to meet specific security needs.

Packet filtering firewalls, for example, protect entire networks by inspecting packets as individual units and filtering them based on their source, destination, and other criteria. Stateful inspection firewalls, on the other hand, monitor traffic within the context of a network connection, allowing them to recognize malicious activity and block it more effectively.

By understanding how different firewalls monitor traffic, organizations can choose the most suitable solution for their particular security requirements.

Importance of Firewall Protection

The importance of firewall protection cannot be overstated. By securing your network from unauthorized access and malicious cyberattacks, firewalls help protect sensitive data and resources from potential harm. For businesses, firewalls can help keep employees focused on work-related tasks by limiting access to online ads, gaming, and certain social media platforms. In educational institutions, firewalls ensure a safe online environment for students and staff by restricting access to inappropriate content.

Firewalls also play a crucial role in securing supply chain networks, safeguarding the value and confidentiality of goods, services, pricing, and production information. By regularly updating firewall software, employing multiple layers of defense, and monitoring network traffic, organizations can maximize their firewall protection and stay ahead of ever-evolving cyber threats.

Types of Firewalls: Diverse Solutions for Varied Needs

In a world where cyber threats are constantly evolving, it’s essential to choose the right type of firewall to protect your network. Different types of firewalls offer diverse solutions to address varied security needs, such as packet filtering, stateful inspection, proxy, next-generation firewalls (NGFW), network address translation (NAT), and virtual firewalls. By understanding the strengths and weaknesses of each type, organizations can select the most appropriate solution for their specific network security requirements.

Each type of firewall has its unique approach to inspecting and filtering network traffic. Some firewalls focus on analyzing individual packets, while others examine traffic within the context of a network connection or at the application level. With a myriad of options available, it’s crucial to understand the capabilities and limitations of each type to ensure the most effective defense against cyber threats.

Packet Filtering Firewalls

A packet filtering firewall is the most basic type of firewall, inspecting packets individually and filtering them based on a set of predefined rules. By examining the source, destination, and other criteria associated with each packet, packet filtering firewalls can decide whether the data should be allowed through or blocked.

However, packet filtering firewalls have their limitations. They are unable to stop web-based attacks, as all web traffic is allowed through without content filtering. Additionally, packet filtering firewalls are susceptible to IP spoofing attacks and have mostly been replaced by stateful inspection firewalls for improved security.

Stateful Inspection Firewalls

Stateful inspection firewalls, also known as stateful inspection firewalls, are a step up from packet filtering firewalls, offering more advanced security by monitoring traffic within the context of a network connection. By examining both incoming and outgoing packets, stateful inspection firewalls can recognize and block malicious activity more effectively. They maintain a record of all open connections and filter traffic based on state, port, and protocol, as well as rules and context set by the administrator.

Despite their enhanced capabilities, stateful inspection firewalls are not immune to vulnerabilities. They can be prone to denial of service (DoS) attacks, which exploit the established connections that these firewalls usually consider secure. To counter these threats, organizations should consider implementing additional security measures, such as intrusion prevention systems or deep packet inspection firewalls.

Proxy Firewalls

Proxy firewalls offer a more precise level of control over network traffic by acting as an intermediary between the user and the internet. They inspect the contents of packets to differentiate legitimate requests from malicious code that may be disguised as an ordinary request for data. By providing a more detailed approach to traffic analysis, a proxy firewall grants security engineers greater control over network traffic and allows them to implement more stringent security policies.

However, proxy firewalls can sometimes suffer from performance issues due to the additional processing required to inspect packet contents. Despite this drawback, the increased security and granular control provided by proxy firewalls make them an attractive option for many organizations.

Next-Generation Firewalls (NGFW)

Next-Generation Firewalls (NGFW) represent the cutting edge of firewall technology, featuring advanced capabilities for deep packet inspection and threat prevention. By inspecting packets at the application level of the TCP/IP stack, NGFWs can identify and enforce security policies for specific applications, such as Skype or Facebook. Additionally, NGFWs incorporate sandboxing technologies and threat prevention features like intrusion prevention systems (IPS), antivirus software, and software firewall to detect and prevent malware and other threats in real-time. As a result, network firewalls have evolved to become more sophisticated and effective in securing organizations’ digital assets.

The adoption of NGFWs allows organizations to stay one step ahead of evolving cyber threats, providing deeper inspections of data traveling in and out of the network. With their advanced capabilities, NGFWs are becoming an increasingly popular choice for organizations seeking robust and comprehensive network security solutions.

Network Address Translation (NAT) Firewalls

Network Address Translation (NAT) firewalls offer an additional layer of security by preventing unwanted communication from reaching private IP addresses. By translating public IP addresses into private ones, NAT firewalls ensure that only incoming web traffic requested by a device within the private network is allowed through.

This type of firewall is particularly useful for organizations that rely on static IP addresses, as it can prevent malicious activity from reaching their private IPs. By implementing a NAT firewall, organizations can enhance their network security and better protect sensitive resources from external threats.

Virtual Firewalls

Virtual firewalls work in a similar way to physical firewalls by filtering traffic based on IP address, ports, protocols, and other criteria. This provides security for both virtual machines and networks. Virtual firewalls have many security features to offer; including application-level security, intrusion detection and intrusion prevention. These features make them a great way to keep your network secure.

As organizations increasingly adopt cloud-based infrastructures, the demand for virtual firewalls is on the rise. Cloud-native firewalls, a subtype of virtual firewalls, are specifically designed to work within cloud-based environments, providing seamless security for virtual machines and containers running in the cloud.

With the growing prevalence of virtual environments, virtual firewalls represent an essential component of modern network security strategies.

Software vs Hardware Firewalls

When it comes to firewalls, organizations may choose between software or hardware solutions, each with its own advantages and disadvantages. Software firewalls are installed on individual devices, inspecting and filtering traffic for that specific device. They are often more straightforward and less expensive to implement but may consume valuable system resources on the device. On the other hand, hardware firewalls are physical devices that filter network traffic to protect both the network and its endpoints. They are typically more robust and can handle higher traffic loads, but may be more challenging and costly to install and maintain.

Organizations should carefully consider their specific needs before deciding on the most suitable firewall solution. Factors such as network size, budget, and desired level of security should be taken into account when choosing between software and hardware firewalls. In some cases, implementing both hardware and software firewalls can provide an extra layer of security, offering a comprehensive defense against cyber threats.

Enhancing Firewall Security with VPNs

Adding a Virtual Private Network (VPN) to your network security arsenal can further enhance your firewall protection. VPNs work in tandem with firewalls, encrypting data and providing an additional layer of defense against cyber threats. By creating a secure connection tunnel, VPNs help to safeguard your data from interception and eavesdropping while traversing the internet.

VPNs can be especially useful for organizations with remote workers or multiple office locations, as they ensure secure and encrypted communication between devices and networks. By incorporating a VPN into your network security strategy, you can bolster your firewall’s effectiveness and better protect your organization from potential cyberattacks.

Firewall Vulnerabilities and How to Address Them

Even the most robust firewalls are not immune to vulnerabilities. Common firewall weaknesses include misconfiguration, outdated software, and lack of user authentication. To address these vulnerabilities, organizations should take steps such as regularly updating their firewall software, employing multiple layers of defense, and monitoring logs for any suspicious activity.

Additional security measures, such as intrusion prevention systems and deep packet inspection firewalls, can also help mitigate the risks associated with firewall vulnerabilities. By staying vigilant and proactive in addressing potential weaknesses, organizations can ensure their firewalls remain an effective line of defense against evolving cyber threats.

Best Practices for Maximizing Firewall Protection

To maximize the effectiveness of your firewall protection, it’s essential to follow a few best practices. First and foremost, regularly update your firewall software and operating systems to protect your device from potential exploits and security breaches. Employ multiple layers of defense, such as intrusion prevention systems, to enhance your firewall’s capabilities and safeguard your network from a broader range of threats.

Monitor your firewall’s logs and rules for any changes or suspicious activity, including malicious traffic, and make sure all rules are up to date and only necessary ports are open. Ensure access is restricted to authorized users and disable any unnecessary services or software to reduce potential attack vectors.

By adhering to these best practices, you can maximize your firewall protection and keep your network safe from cyber threats.

The Future of Firewalls: Emerging Trends and Technologies

As cyber threats continue to evolve, so too must firewall technology. Emerging trends in firewall protection include cloud-based firewalls, AI-driven firewalls, and zero-trust architectures. Cloud-based firewalls provide security for virtual machines and networks in cloud environments, ensuring seamless protection for organizations adopting cloud-based infrastructures.

AI-driven firewalls leverage artificial intelligence to detect and respond to threats in real-time, staying one step ahead of cybercriminals. Zero-trust architectures, on the other hand, adopt a security model that assumes all users and devices are untrusted and require authentication and authorization before granting access, providing a more comprehensive defense against internal and external threats.

By staying informed about emerging trends and technologies in firewall protection, organizations can ensure they remain at the forefront of network security, proactively safeguarding their assets and data from ever-evolving cyber threats.


In conclusion, firewalls play a crucial role in protecting networks from cyber threats and unauthorized access. With a variety of types and technologies available, organizations must carefully consider their unique needs in order to select the most appropriate firewall solution. By following best practices, addressing vulnerabilities, and staying informed about emerging trends, organizations can maximize their firewall protection and confidently navigate the ever-evolving landscape of cybersecurity.

How to stay safe online:

  • Practice Strong Password Hygiene: Use a unique and complex password for each account. A password manager can help generate and store them. In addition, enable two-factor authentication (2FA) whenever available.
  • Invest in Your Safety: Buying the best antivirus for Windows 11 is key for your online security. A high-quality antivirus like Norton, McAfee, or Bitdefender will safeguard your PC from various online threats, including malware, ransomware, and spyware.
  • Be Wary of Phishing Attempts: Be cautious when receiving suspicious communications that ask for personal information. Legitimate businesses will never ask for sensitive details via email or text. Before clicking on any links, ensure the sender's authenticity.
  • Stay Informed. We cover a wide range of cybersecurity topics on our blog. And there are several credible sources offering threat reports and recommendations, such as NIST, CISA, FBI, ENISA, Symantec, Verizon, Cisco, Crowdstrike, and many more.

Happy surfing!

Frequently Asked Questions

Below are the most frequently asked questions.

What is the purpose of a firewall?

The purpose of a firewall is to protect a network from malicious activity by filtering incoming and outgoing traffic according to established security rules. Firewalls provide an essential layer of security for networks by monitoring traffic and restricting access to unauthorized users or activities.

What are the 3 main functions of a firewall?

Firewalls are an essential security measure, serving three main functions: they prevent unauthorized access to networks, protect sensitive data from being compromised, and maintain the privacy of computer systems and networks.

These functions are critical for any organization that stores or transmits sensitive data, as they help to ensure that only authorized users can access the data and that it remains secure. Firewalls also help to protect against malicious attacks, such as viruses, worms, and other forms of attacks.

Is it really necessary to have a firewall?

The short answer is yes – having a firewall in place is absolutely necessary. Firewalls are the first line of defense against external attacks and can be used to regulate traffic within the network. They provide an extra layer of protection for your computer or network from malicious activity, viruses, and other forms of cyber-attack.

Yes, it is essential to have a firewall in place to protect your network and data from outside threats. Firewalls act as a shield by preventing malicious software from entering your system or network and allowing you to control which connections are accepted into your home network. Having a firewall in place ensures that your data remains safe and secure.

Does a firewall protect against hackers?

Firewalls are an important security measure against hackers. They create a barrier between your computers and the internet, blocking malicious traffic and alerting you to any potential threats.

Firewalls help protect you from a variety of cyber-attacks, keeping you and your data safe. By implementing a firewall, you can minimize the risk of cyber-attacks and keep your business safe.

What is a firewall?

Firewalls are an important network security measure that can help protect your organization from malicious threats coming from the outside. By using a firewall to filter incoming and outgoing traffic, you can create a secure barrier between your internal network and the public Internet to protect against malicious intruders.

Author: Tibor Moes

Author: Tibor Moes

Founder & Chief Editor at SoftwareLab

Tibor has tested 39 antivirus programs and 30 VPN services, and holds a Cybersecurity Graduate Certificate from Stanford University.

He uses Norton to protect his devices, CyberGhost for his privacy, and Dashlane for his passwords.

You can find him on LinkedIn or contact him here.