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What is a firewall?

21 Sep , 2017, 14.56 Linus Nyman


A firewall is an important part of your security. But what the heck is a firewall? If you’ve ever asked yourself that very question – or if your smorgasbord of small-talk topics for cocktail parties needs some spicing up, this is the post for you.

Firewalls as bouncers

The easiest way to think of a firewall is as a bouncer – a guard standing watch in front of a door. The bouncer’s objective is to examine all the traffic that wants to get past it. And to stop anything suspicious from actually getting through the door.

There are two different kinds of bouncers – or two different places where bouncers are commonly found. One group of bouncers is those that stand guard at a specific machine. The other group is the bouncers who stand guard between different networks.

Bouncers guarding individual machines

An easy example of bouncers for individual machines would be: pretty much any computer. Both Windows and Mac computers come with firewalls. These firewalls are software-based. Meaning, they are computer programs that are already on your machine when you buy it.

(But – Fun Fact: firewalls can also be hardware-based!) (However, [Bonus Fun Fact] hardware-based firewalls will also have firewall-related software running on them.)

Bouncers guarding networks

One example of network bouncers is a firewall between your local network at home –  the computers you have at home that are connected to (commonly) the Internet – and the Internet itself.

The connection between your local network and the Internet usually goes through a modem (that small box with antennae and the WiFi password sticker on the back). In connection with this modem you might have a network bouncer – a firewall – examining all the traffic as it passes through.

(Fun Fact: Even if you don’t have an actual firewall built in to your modem, your router actually acts as a firewall; or at the very least a “firewall-light”.) (Protip: it’s worth keeping in mind that there are a limited amount of cocktail parties where insights about the multi-purposefulness of routers are considered “Fun Facts”.)

As you can see, even the shallowest of discussions of firewalls provides topics for countless hours of enjoyable small-talk!

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