Firewalls - An Introduction

A firewall is a piece of software (There are also hardware firewalls but we are going to discuss software only) that blocks or allows incoming or outgoing connections from your computer. I would probably recommend that every computer user should have one as they can protect your computer from hackers, viruses, trojans etc. They are also useful when trying to prevent someone from connecting to an internal service in an organisation, for example an Intranet. There are a number of techniques a firewall can use to defend you computer:

- Packet filter

- Application gateway

- Proxy server

Packet Filter

This type of firewall inspects every packet that tries to enter your computer. It will look at each individual packet and analyse it based on a set of rules. as to whether it is safe or dangerous. These rules can be based on source IP address, destination IP address, which port it is coming through, the type of service (FTP, Internet etc.) plus many other factors can be taken into account.

Application gateway

An application gateway is when a firewall will inspect any program trying to access/connect with your computer, these are especially effective against stopping any viruses or trojans as they recognize the program and prevent it entering your computer and causing any damage.

Proxy server

A proxy is kind of like a veil, it will block anyone from seeing your true IP address, making it harder for anyone to hack/connect with your computer. There are of course ways around this but it adds an extra challenge for the attacker.

This is just a basic introduction to firewalls and the technology they use to protect your computer.

If you want to learn more or need to download a firewall, visit the following link: Bulletproof PC