Want to keep your computer protected? You probably have a firewall, but do you know how they work? Even if you’ve got a bit of an idea, you might not know everything—and that’s what this article is for. Whether you’ve been using them for years or are new to computers, firewalls are important to have. In this article, we’re going to look at what they are and why you need them—as well as how they work.

The term “firewall” comes from an actual physical wall that was traditionally used to hold fire back in a building. It is a feature of many factories and industrial buildings that might be prone to fire. However, that’s not really what a firewall is known as now, the term has taken on a life of its own and most of the time when you hear someone talking about a firewall these days—they’ll be talking about computers.

There are actually two different types of firewalls, hardware and software ones. Hardware firewalls are built into your modem or router whereas the more common software firewalls install a piece of software on your computer that does a similar job. But what is that job?

Firewalls are designed to stop malicious attacks, hackers and viruses. If you didn’t have a firewall, hackers and other people might be able to connect to your computer over the internet and access your files (or perform other tasks). This obviously has a number of severe security implications and could lead to the loss of personal information, money, or a corruption of your system. Firewalls act as a block to these sorts of attacks, they’ll also stop certain other software from opening holes in your system and will guard against other malicious threats to your computer and online security. But how do firewalls actually work? Let’s have a look…

How do firewalls work?

A firewall is either a piece of software or hardware, but they both do generally the same thing—although slightly differently. A firewall is generally used to filter anything that comes from the internet and to your computer (or onto your home network). Filters can flag certain “packets” of information and block them for a number of reasons. Packets are the tiny bits of data that your computer sends and receives, that makes up parts of larger files or information.

Firewalls are useful to businesses that have lots of computers all using the same internet lines to connect to the outside world. All these different employees mean you have to protect all of them, and make sure nobody is receiving malicious data or allowing access to someone they shouldn’t.

But these firewalls aren’t just for businesses. There’s so much on the internet these days that everyone needs one to browse and interact safely. That means every home user should have a firewall. While hardware firewalls might be hard to set up if you don’t know much about networking and hardware, software firewalls are easy to install and get used within minutes. They’re designed for people who aren’t that tech-savvy, so they’re a good option.

Without a firewall, hackers can probe your connection to try and either open up or access open ports. They might try and make FTP connections or open a telnet connection. Then they can get access either to your computer or network so they can perform further tasks. You want to avoid this sort of thing, that’s why you need a firewall.

With a firewall, it’s much harder for people to gain access. A set of rules and barriers can be put in place by the firewall to only allow access on certain ports, or only allow certain limited access to your computer or network. That means FTP ports can be protected or blocked, as an example.

Firewalls can also help block the data that leaves your computers as well as what comes in. That means you can keep sensitive data private or not allow certain information to leave your systems.

FIrewalls generally use three different ways to handle traffic in and out of your business. The first of these is known as packet filtering. With packet filtering, the tiny packets of data we mentioned earlier are observed and filtered. Those packets that don’t fit a certain criteria are discarded and not allowed access. Only the packets that meet the criteria of the filters in place are allowed through.

Another method firewalls use is called proxy service. This is where information is analyzed by the firewall and then sent to where it has been requested from.

There’s also what’s known as a stateful inspection. This is a slightly newer technology that some older firewalls don’t use. In stateful inspection, the firewall doesn’t check each individual packet but compares important parts of packets to known information and an external database about what trusted files will look like. So the data is monitored for certain characteristics and then either blocked or allowed through depending on if the data fits the right criteria or not.

Firewalls are fully customizable. While they come with a certain range of settings, you can adjust them so that you can use your own connection more efficiently. Exceptions can be added to your firewall to allow access to certain computers, connections, files or pieces of software. Otherwise, you might find something blocked that you want to use. So you can add exceptions so that the firewall allows certain software to get through. You can also add exceptions based on IP addresses (which relate to other computers) or ports.

Hopefully, you now know a bit more about how firewalls really work. For extra protection, you might want to consider both a hardware and a software firewall. But if you’re just starting out, a software firewall could be enough. Have a lookout there to see what’s available.

About the Author James S

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