Firewalls are among the most common, as well as effective, cybersecurity tools. They are used by businesses and consumers alike to protect against cyber attacks. Once deployed, a firewall will monitor traffic coming into and going out of a network. If it identifies a data packet as being malicious, the firewall will block it. With that said, there are several types of firewalls, including layer 3 and layer 7 firewalls. While they both work by monitoring and filtering network traffic, they aren’t the same.

What Is a Layer 3 Firewall?

A layer 3 firewall is a type of firewall that operates on the third layer of the Open Systems Interconnection (OSI) model. Also known as the network layer, the third layer of the OSI model is the same where routers operate. Therefore, layer 3 firewalls are able to monitor and filter traffic using the same protocols as routers. They can scan traffic based on Internet Protocol (IP) address, port addresses and similar router-based protocols.

What Is a Layer 7 Firewall?

A layer 7 firewall, as you may have guessed, is a type of firewall that operates on the seventh layer of the OSI model. Also known as the application layer, the seventh layer of the OSI model allows for more advanced traffic-filtering rules. Rather than filtering traffic by IP addresses, layer 7 firewalls can actually analyze the contents of data packets to see if they contain malware or other cyber threats.

Choosing Between a Layer 3 and Layer 7 Firewall

Because they operate on different layers of the OSI model, layer 3 firewalls and layer 7 firewalls don’t offer the same level of protection against cyber threats. Layer 3 firewalls use more generalized rules to filter traffic than their layer 7 counterparts.

With a layer 3 firewall, you can configure it to block specific IP addresses. If your business’s network was recently hit with a distributed denial-of-service (DDoS) attack, you can add those IP addresses to the layer 3 firewall’s ruleset. Unfortunately, though, layer 3 firewalls aren’t capable of inspecting the contents of data packets — and that’s where a layer 7 firewall comes into play.

Layer 7 firewalls are more advanced than layer 3 firewalls. They can look into the contents of data packets coming into and out of your business’s network to determine whether they are malicious. If a data packet contains malware, the layer 7 firewall can reject it.

Which type of firewall should you use? You don’t have to limit yourself to using only one type of firewall. You can use both a layer 3 and a layer 7 firewall to achieve greater protection against cyber threats.

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