Basic Ubuntu Linux Firewall Configuration

A firewall is a vital component in protecting a computer system, or network of computers from external attack (typically from an internet connection). Any computer connected directly to an internet connection must run a firewall to protect against malicious activity. Similarly, any internal network must have some from of firewall between it and an external internet connection.

This chapter will cover the steps necessary to install and configure an Ubuntu Linux firewall.

The desktop edition of Ubuntu Linux is unusual amongst recent operating systems in that it does not install any firewall software by default. Whilst on the surface these seems odd it is likely that the Ubuntu team assume that most individuals and companies already have some of firewall in place. In the case of companies it is probably in the from of a sophistication proxy and firewall configuration. In the case of a home user it is liely in the form of a router or wireless base station with built in firewall capabilities. Unfortutely many wireless base stations are configuired by default to transmit data without any form of encyption leaving the network (and the computers connected to it) wide open to anyone close enough to pick up the signal.

Ubuntu Linux provides two firewall options. The first is a basic yet effective and easy to use firewall configuration system called lokkit. Another, more advanced, option is called GuardDog. Whilst still not an extremely complex firewall system, GaurdDog provides flexibility over and above that provided by the lokkit system.

In this chapter we will explore lokkit and in the next chapter (Installing and Configuring a GaurdDog Firwewall on Ubuntu) we will look at the GaurdDog firewall in more detail.