We all use computers, and we all value privacy, so in trying to access networks like the Internet for work or fun, we have to make sure that we are protected from malicious cyber attacks that target our private data.
That’s where firewalls come into play. A firewall is a security tool that filters incoming and outgoing traffic in a network. Its goal is to block bad traffic and only allow legitimate traffic into the network.
The Eight Types of Firewall
There are different types of firewalls, and they are categorized depending on their structure and methods of operation.
Hardware Firewall
As the name suggests, a hardware firewall is a physical device that intercepts data packets and traffic requests from the external network such as the Internet before they get connected to a network’s internal servers. It is also known as an appliance firewall.
Because it is a separate device, the hardware firewall doesn’t consume any CPU or RAM from the host device and won’t be affecting the network speed. This is why medium- to large-sized organizations use the kind of firewall because it’s those kinds of institutions that have multiple computers working within one network.
Software Firewall
Another structure-based type of firewall is the software firewall. Instead of being separate from the host device, it’s installed in it; that’s why it is also aptly known as a host firewall. A major benefit of a software firewall is that it’s useful for an in-depth defense by isolating network endpoints from one another. It can distinguish between programs while filtering traffic.
However, since it’s in the host device itself, it can use up the ram and CPU. And if there are multiple devices connected to your network, you’ll have to manually configure the firewall for each device because it needs to be compatible with the host. Hence, making it time-consuming and would require an expert to handle.
Cloud-based Firewall
A cloud firewall is also known as a firewall-as-a-service. Like other cloud solutions, it’s maintained and run on the Internet by third-party vendors.
The main advantage of using a cloud-based firewall is its scalability. Because it’s on the cloud, there is no need for physical resources. As your organization grows, you can add capacity to your cloud servers to accommodate larger traffic loads.
Packet-filtering Firewall
The packet filtering firewall is a type of firewall categorized based on its method of operation, which is packet filtering. It is considered the oldest of the firewall types. Its primary function is to create a checkpoint at a router or switch and perform a simple check of the data packets that go through the router. It usually only checks surface-level inspection of the packets like destination and origin IP address, packet type, and port number without actually inspecting its contents.
Because of its simple functionality, it isn’t a resource-intensive firewall. However, it is also easy to bypass this kind compared to the other types of firewall.
Circuit-level Gateways
Circuit-level gateways are also another simplistic type of firewall. It operates by verifying the transmission control protocol connections and sessions. It just ensures the session where the packet came from is legitimate.
Similar to the previous type, it also doesn’t check the content of the packets it filters and is also not very resource-intensive. It’s simple to set up and doesn’t require a separate proxy server, but the level of security it provides is still lacking compared to today’s standards.
Stateful Inspection Firewall
The stateful inspection firewall is a little more advanced than the last two because it combines bot packet-filtering and TCP verification. This allows it to keep track of the entire connection and creates a greater level of protection.
Because of the combined functionalities, the stateful inspection firewall can enforce more checks and inspect actual data instead of just the headers. Unfortunately, this also means that this type uses up more resources and can slow down the transfer of legitimate packets.
Application-level Gateways
An application-level gateway filters the traffic flow on the application layer, hence the name. It is also called a proxy firewall because how it works is it establishes a connection to the source first by forwarding requests from the user and masking it as its own, as a proxy. Once the web server it’s connected to responds, the proxy then passes on the information to the user.
This firewall is similar to stateful inspection in that it looks at the packet and the TCP handshake protocol. But it can also perform deep packet inspection and inspect the packet contents to verify that there is no malware. However, the extra steps in masking the client’s identity and the deep packet inspection can significantly slow down data transfer.
Next-generation Firewalls
A next generation firewall is the most advanced of the firewalls listed because it combines the features of its predecessors. It incorporates packet, stateful, and deep packet inspection to thoroughly inspect each packet and ensure no malicious content will go through. Aside from those functions, most next generation firewalls also include an intrusion prevention system that detects and automatically blocks all kinds of attacks on your network.
The Next Step: AI-enabled Next Generation Hardware Firewall
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