Why you need to install and use a firewall to secure your computer.

Beginner Series

Securing a computer is a multiple step process that does not have to be complicated or expensive. The first step in securing your computer or laptop is a firewall, and all devices connected to the Internet should be running one.
Why a firewall? Firewalls help protect you from hackers; some viruses that scan networks for other devices to infect, and some can even notify you if malware or a virus on your computer is trying to connect; or upload information to the Internet without your knowledge.
Firewalls come in two forms; one is what is known as "software" firewall and the other is a hardware firewall.
First of all what is a software firewall? A software firewall runs directly on the computer or laptop. A software firewall can be built into an Operating System like Windows XP and Vista, purchased from a third party company like Symantec, and there are also several free software firewalls, several of which I have provided links to at the end of the article.
Software based firewalls work by inspecting network traffic and deny incoming requests from the Internet or Local Area Network to a program or the port which the program listens, unless the user has rules in place that allow traffic to a port or application. An example of a rule would be opening port 5800 or 5900 to allow someone; such as help desk personnel to remote control your computer using VNC to troubleshoot applications or Operating System issues or to resolve other problems.
What is a hardware firewall? A hardware firewall is a device that connects computers on a Local Area Network to the Internet. Most home users have a hardware firewall in place and that is the Router that we purchase to connect multiple computers and laptops to the Cable or DSL Modem supplied by your Internet Service Provider.
Most hardware firewalls or routers use packet filtering to examine the header of a packet (network traffic or data) to determine its source and destination. This information is compared to a set of predefined or user-created rules that determine whether the packet is to be forwarded or dropped. Most of these home devices come with all ports blocked but have an easy to use web based interface to allow the opening of certain ports for data transfer; gaming, etc. A word of caution before opening ports on a firewall, verify that your ISP allows the service, port, or application that you are opening up on their network. I know of at least one ISP in particular will suspend your account for opening the telnet port; port number 23 or ftp and sftp ports 20 and 21 as a violation of their terms of service.
Which type of firewall to use is up to you, and it does not hurt to use a software firewall along with the hardware firewall, but do not use two software firewalls at the same time. Software firewalls are included in almost all operating systems, relatively inexpensive, or free.
My next article will show the setup and configuration of the firewalls included with Windows XP and Vista.
The following list does not include every software firewall, nor is it a recommendation of one versus the other, but the list is a starting point. Also use your favorite search engine to find the "top ten" firewalls and read the reviews.

1. Comodo – http://personalfirewall.comodo.com/
2. Outpost Firewall Free - http://free.agnitum.com/
   
3. Online Armor Personal Firewall - http://www.tallemu.com/product_overview.html

Matthew L. Davidson

Lexington KY