Which of the following firewalls operate at the network layer of the OSI model?

I understand that Firewalls may operate on different OSI layers depends on the firewall itself. but how can I know if I install specific firewall at what OSI Layer(s) it does operate ?

asked Mar 8, 2015 at 18:20

4

Since firewalls essentially filter data, the answer depends on what kind of filtering you do.

If you filter based on IP address (for example), you can say that your firewall is filtering at layer 3. If you filter specific ports, you can say you're filtering at layer 4. If your firewall inspects specific protocol states or data, you can say it operates at layer 7.

The truth is that most firewalls do all these things in combination. So practically speaking there really is no useful answer to your question.

May I suggest you also read this question about the OSI model.

answered Mar 8, 2015 at 21:39

Ron TrunkRon Trunk

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Unless your firewall uses the OSI model, it is of little value to speak about it in these terms. You should bear in mind that the TCP/IP model only has five layers.

That being said, it largely depends on if your firewall is capable of doing Deep Packet Inspection. If it is, it operates at L3/L4 and at the Application Layer. Otherwise, it only filters at the IP and Transport layers.

On the other hand, it "Operates" at all layers except for the application layer. It must have a physical connection, provide a data link/Network connection and enforce NAT policies and firewall rules at the IP layer and Transport layer. If it didn't it would not be a functioning firewall.

answered Mar 9, 2015 at 4:31

It depends on what kind of firewall. There are three basic types: Generation 1 Packet Filter runs at layer 3, Generation 2 Stateful Filter runs at layer 5, and Generation 3 Application Firewall (also known as NGFW: Next Generation Fire-Wall.)

answered Oct 11, 2018 at 18:56

1

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.

#firewall #layer3 #layer7

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