A network firewall is a security tool that blocks illegitimate access to networks connected to the wider internet.

Companies install network firewalls to create a protective shield around data centers and critical workloads. Network firewall filters process all inbound and outgoing traffic. They deny access for malware and outsiders, while having minimal impact on authorized users.

The result is robust data security, improved threat detection and streamlined access management. Read on to explore how network firewalls work, and why they matter.

How does a network firewall work?

Network firewalls create a virtual perimeter around network endpoints. A well-calibrated network firewall will enforce security policies to regulate network access, block dangerous traffic and allow free movement for everything else.

Network firewall scheme

Pre-defined rule sets and policies govern how the firewall works. IT teams decide what represents a threat and what traffic types to prioritize. Policies may also include user profiles to verify authentic access requests. The firewall automatically applies these policies.

In some cases, firewalls use machine learning to adapt as new threats emerge. Filters may refer to global threat databases or connect to SIEM security tools used by the organization.

The firewall inspects traffic passing through the network firewall at four TCP/IP layers. Firewalls generally operate at the data link, network, transport, and application levels. Cutting-edge next-generation firewalls can operate at higher TCP/IP layers, gathering maximum information about every data packet.

Network firewalls come in various forms. Older network firewall technology relies on simple inspection mechanisms like packet filtering. Packet filtering monitors data headers, but cannot penetrate the content of data packets.

By contrast, stateful or next-generation network firewalls use deep packet inspection (DPI) to peer into the content of web traffic. These more advanced products provide a stronger line of defense for network infrastructure.

Why do you need a network firewall?

Organizations need network firewall security because the assets they hold are vulnerable to external attacks. Next-generation firewalls protect applications and data with robust filters and traffic inspection. Attackers must breach those barriers before accessing confidential data or disrupting network performance.

Efficient network firewalls blend filtering with scalability. Protection extends as the network expands. Companies might add new cloud assets or branch locations. This leads to new vulnerabilities unless firewalls adapt. A specialist network firewall scales smoothly, making it easier to secure rapidly changing IT environments.

Network firewalls also bridge local and cloud environments. Traditional firewalls tend to lack this capability. Cloud-hosted next-generation firewalls sit inside the cloud. They process traffic passing between local workstations, remote devices, and SaaS providers. This provides stronger protection for the cloud assets modern businesses rely on.

Network firewall use-cases

Firewalls play a range of practical roles in contemporary networks. Common network firewall use cases include:

Preventing inbound internet traffic intrusion

Network firewall tools are a powerful way to filter inbound traffic. Networks require protection against viruses, ransomware, Trojans, and worms. Firewalls use tools like protocol detection and stateful inspection to monitor incoming traffic. They block malicious agents while allowing free entry to authorized traffic.

Filtering outbound traffic

Firewalls also secure traffic leaving networks. This has a number of benefits. Malware may communicate with external devices to relay stolen data. The firewall blocks this process, minimizing the risk of data exfiltration.

Employees may also move data or files without authorization. Firewalls settings can block specific file types and ensure data remains where it needs to be. For example, companies may want to tightly regulate outgoing traffic like patient health records or customer financial information. Outbound firewall filtering achieves these goals.

Customizing Virtual Private Clouds (VPCs)

Many companies use VPCs to host workloads and store data. Cloud-optimized network firewalls can apply logical segmentation to protect virtual devices. Companies can store critical assets behind rock solid protective walls. Less sensitive apps or data are freely accessible. Admins can toggle access privileges to ensure only authorized individuals can access high-value data.

Benefits of a network firewall

Several features that make network firewalls a valuable addition to network security infrastructure. Firewall benefits for organizations include:

  • Inbound and outbound traffic filtering – The core goal of network firewall security. IT teams can filter traffic arriving at the network edge. Firewalls block viruses and malware along with malicious code or unauthorized users. They can also regulate outgoing traffic. This blocks the departure of sensitive data and disrupts outward-bound malware communications.
  • User freedom – With firewall filtering in place, employees can use the external internet safely. Employees can visit websites they need. Any hazardous code generated by malicious websites will be blocked, and any malware will remain outside the network perimeter.
  • Network endpoint coverage – Firewalls optimized for networks cover all relevant endpoints. This includes user laptops, mobile devices, workstations, and assets like routers or IoT sensors. When a device establishes a connection between the internet and the network, your firewall will take effect.
  • Segmentation – Smart next-generation firewall tools can apply internal and external filters, segmenting assets within the network. Firewall settings prevent some forms of traffic entering segmented areas, while allowing others. This creates zones of security in line with SASE and Zero Trust approaches.
  • Compliance – Companies are subject to multiple cybersecurity regulations, including GDPR, PCI-DSS, and HIPAA. Firewall systems are a core part of regulatory frameworks. Organizations must have a solid firewall in place to meet their compliance goals and prove they have a strong data security setup.

What is the difference between a traditional firewall and a network firewall?

When we talk about network firewalls, we are really discussing a subset of firewalls in general. Network firewalls are digital filters that protect company networks. They are designed to regulate access to endpoints on intranets, LANs and WANs. Advanced versions also include cloud filtering to protect SaaS applications.

Network firewalls filter the type of traffic commonly faced by business networks. This includes email filtering, URL filters, and malware or antivirus protection. It also includes protection against access attempts by unauthorized users. The aim is to guard on-premises or cloud-based network resources.

Traditional firewalls perform other roles. For instance, firewalls might set out to protect individual devices in home settings. IoT firewalls specialize in defending webs of IoT devices. And Wi-Fi firewalls guard public wi-fi environments against malicious attacks.

To summarize: network firewalls are critically important business tools. They protect network assets against malicious agents, regulate access, and make network resources available without compromising security.