Chapter 1. Introduction

Guarddog is a user friendly firewall generation and management utility for KDE running on Linux. It allows you to simply specify which network protocols should be allowed between which groups of computers without requiring you to have knowledge of port numbers or packets. Guarddog is built on top of Linux's ipchains and iptables packet filtering commands.

What is a firewall and why do I need one?

A firewall is a software and/or hardware tool for defending a computer or network of computers, from attacks via the network performed by malicious or curious computer users. It protects by restricting what hostile computers are permitted to do to the protected computers. It does this by filtering and blocking the network communication between the protected computers and the Internet at large.

With the arrival of fast, permanent, 24 hour/7 day, internet connections for home users, your computer is now exposed to constant attacks from anywhere in the world. You may ask yourself "why would anyone want to break into my computer? I don't have anything important". Actually you do, even a home computer stores usernames and passwords for connecting to the internet, personal email, possibly financial information and perhaps even credit card information. Even without these things, your computer can be used as a stepping stone by malicious users (often called 'crackers') to attack other computers. The worst part of this is that these further attacks will look like they are coming from you!

For more introductory material about firewalls try the firewall article over at How Stuff Works.