Very common questions that I see on Ubuntu forums are regarding security. Do I need antivirus, what about a firewall, what about the spyware etc. I'm not a Linux expert just a normal user but in this article I'll try to answer these questions.

1. Firewall

   Firewall is something that everyone connected to network needs regardless of a operating system. As an ex-windows user you would expect a firewall application to run somewhere in the backround and you probably get little bit restless if you can't find any.
   
   A firewall protects a computer system from unauthorized access. It is not normally necessary to install a firewall on an Ubuntu system, because access to the system is closed by default. However, if you run any services that let other computers access yours (for example, the Apache web server), it is advisable to install a firewall. Firestarter is a program that lets you control a firewall through a graphical interface. (Guardog for KDE)
   
   The Linux kernel includes the Netfilter subsystem, which is used to manipulate or decide the fate of network traffic headed into or through your server.  All modern Linux firewall solutions use this system for packet filtering. The kernel's packet filtering system would be of little use to administrators without a userspace interface to manage it.  This is the purpose of iptables and Firestarter (or Guardog) is a graphical interface for iptables.
   
   One thing to note is that once you set the iptables with Firestarter you don't need to run Firestarter in the background. Firestarter is mainly used for setting the rules and viewing of logs. Once you set the rules the job is done. The firewall is running as a part of the Linux kernel so there is no need for running of the graphical interface all the time.
   
   To install Firestarter, go to synaptic or type sudo aptitude install firestarter. For more information about Firestarter visit www.fs-security.com

2. Viruses
   

   At this moment there is only a handful of viruses for Linux and most of them are just a proof of concept. So far I haven't heard of anyone using Linux based OS to catch a virus. It's not impossible but Linux is not targeted as its not used by many people. Another good point is that you are running as a user and you only given temporary admin rights when needed, thus the need to use sudo before any command that you need to run as root.
   
   Nothing can just install without your input, therefore the most important thing is to be smart, install only from the official repositories and you'll be fine.
   
   If you use wine you should be carefull ot to run a windows virus through wine. It is not going to happen on its own but if you click on executable virus file and you have Wine installed on your machine it will probably ask you if you want to run it in wine and if you say yes the virus can infect your /.wine folder and possibly your /home. Read this to find more what happens if you run windows virus in wine.
   
   If you still feel like you want an antivirus or you don't want to pass viruses onto people using windows there are few linux antivirus programmes i.e clamAV (which is in repos), AVG for Linux.

3. Spyware
   

   Its basically the same story as with the viruses, basically nothing to worry about. There are no annoying windows that take over your PC or run in the background. You may wan to install plugin for your browser to block Javascript or something similar but other than that it shouldn't be a problem. 
   

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