How does a Firewall Work?

Posted by: Maxine Brimmer (3 years, 2 months ago)

If you work around computers, or use them often in your daily life, then it’s more than likely that you’ve heard the word “firewall” used multiple times before. Created to increase security for personal computer users and corporations alike, a firewall acts like a barrier to keep unwanted forces out of your computer. Think of a firewall as your computer’s bouncer, keeping destructive threats out, but allowing useful, legitimate sources in.

Firewalls can come both as hardware and software, so whilst most up-to-date operating systems have firewall software installed and turned on by default, it may also be important to look into other security measures. Your firewall is the first line of security between you and people who would like access to your computer and information.

To only allow the right sources access to your computer, a firewall uses 4 basic processes, these are: packet filtering, proxy server, application gateway and circuit-level gateway.

A packet filter looks at traffic coming to and leaving from your network and checks it. You can enter specific criteria for a packet filter to look for as it scans your traffic, it will then filter inappropriate activity out.

A proxy server is generally used to speed access to websites over a large network, however as part of a firewall it can be used to block access to specific websites. This is often used in offices to ban inappropriate web activity.

An application gateway adds extra security to computers behind a firewall, but this might come at the cost of some overall speed.

A circuit-level gateway watches processes between your computer and outside sources to make sure the activity is legitimate, it can be useful for hiding information about protected networks.

Whilst not all 4 of these devices might exist within the same Firewall software, they all have their advantages and drawbacks.

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