In our digital age, it is more important than ever that your devices remain safe and secure. This is where firewalls come in. These digital defense mechanisms have long acted as a barrier from hackers trying to get your personal information. But while you’ve likely heard of firewalls, or maybe even used them, have you ever considered how they work?

First, you need to understand how information is transported through a network. This is done through the Transport Control Protocol (TCP). TCP acts as a guide for packets, which contain the data you want to move through a network. These packets have a variety of data, which not only includes what you want sent across a network, but also identifiers that tell the TCP to who and where the information is going.

This is where firewalls come in. When a data packet reaches a firewall, it is stopped and assessed by the firewall. The firewall is set to only let data packets through if they contain the data allowed by the firewall’s code. If the packet contains this data, then it is allowed to pass. If not, the data packet is rejected, meaning that potentially harmful information can’t enter your part of the network.

There are typically three types of firewalls. These are stateless, stateful, and application layer  Stateless firewalls are the more lenient of the three. This type of firewall can only judge packets based on their individual identification data. Stateful firewalls go one step further, checking the connection type of the packet from where it came from. If it doesn’t meet the standards of the firewall, it will also be rejected. Lastly, application layer firewalls are the most thorough. In addition to the previous two steps, these firewalls can check packets based on the data they are transporting, meaning unsavory data types will also set off the firewall.