Firewalls are a critical security measure for internal networks. These “gatekeepers” help stop hackers and malicious attacks from entering the network while allowing only approved or legitimate traffic in.

As the primary defense against attacks, firewalls help safeguard internal networks from the rest of the internet. A firewall can be hardware- or software-based, and different firewalls may be used together to create a multi-layered approach to security.

So what are the different types of firewalls available for network protection? Here are the five most common types of firewalls explained.

Packet-Filtering Firewall

A packet-filtering firewall is the most basic type of firewall. Although it’s cost-effective and simple to deploy, it doesn’t provide a standalone solution to network security and is best used with additional firewalls.

Packet-filtering firewalls examine each data packet and don’t keep an account of connections. It simply looks at the IP address, port number, and other criteria to determine the legitimacy of traffic. These criteria allow the firewall to approve or block traffic into the network.

This basic type of firewall is not the right choice for organizations that need advanced protection from threats. Still, it can be an affordable option for smaller companies or those wanting to layer firewalls.

Circuit-Level Gateway

Circuit-level gateways provide a more robust level of security than packet-filtering firewalls and are cost-effective and simpler to maintain. As a bonus, they have minimal impact on network performance.

Instead of evaluating data packets, circuit-level gateways verify Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) connections to approve a session and confirm that the outside source is secure. Unlike packet-filtering firewalls, a circuit-level gateway keeps a record of previously approved and rejected connections, which can help businesses identify hacking attempts.

These firewalls are still generally used with other firewalls to provide a higher level of protection, especially since they don’t individually examine data packets.

Proxy Firewall (or Application-Level Gateway)

A proxy firewall, or application-level gateway, is more complex and can affect network performance. However, it provides a higher level of security and security controls, particularly regarding data.

Application-level gateways inspect data packets and provide stateful inspections, combining the best of circuit-level gateway and packet-filtering firewalls. They provide an extra layer of protection because the server never has access to the outside network and user details. This keeps internal networks safe from malicious threats.

This type of firewall generates two connections—one between the user requesting access and the proxy and another between the proxy and the server, so businesses can avoid potentially threatening direct connections to the server and create more protection.

Stateful Inspection Firewall

Stateful inspection firewalls keep a log of established connections while inspecting packets for enhanced security. These firewalls can prevent attacks that take advantage of network vulnerabilities by using fewer open ports.

Although they can be more costly and complex to configure and impact network performance, a stateful inspection firewall provides many organizations with an enhanced layer of protection.

These firewalls verify authentic connections and are able to utilize an active ruleset that updates over time to filter traffic rather than fixed pre-programmed rules, which allows for a more dynamic firewall setup.

Next-Generation Firewall

Next-generation firewalls are different from traditional firewalls in that they can combine different firewalls into one solution and work for industries that require a high level of data security, including healthcare and Payment Card Industry (PCI) companies.

These contemporary firewalls provide deep packet inspection (DPI), which means they closely inspect each packet’s data. They can also track sessions while providing additional security functions, such as integration with other systems, malware scanning, and encryption.

Although efficient and ideal for industries that need robust firewall solutions, they require some skill to configure and more resources to deploy. In addition, next-generation firewalls can also slow network performance, so keep this in mind when considering this type of firewall.

Which Firewall Is Right for You?

No one firewall is right for every organization. They each have pros and cons, and some need to be used in conjunction with others. It also depends on whether you have the talent to properly configure and maintain firewalls for the utmost performance. However, as attacks continue to grow in frequency and sophistication, it’s imperative to have a multi-faceted approach toward security that includes firewalls.