A firewall is basically the first line of defense for your computer, because it can restrict traffic coming into or going out of your network or computer. Setting up a firewall can help to protect your computer from hackers, worms and viruses.

The basic purpose of a firewall is to keep uninvited guests from browsing your network. A firewall can be a hardware device or a software application and generally is placed at the perimeter of the network to act as the gatekeeper for all incoming and outgoing traffic.

There are hardware firewalls built into dsl routers and network routers. Make sure to use all of the security features in these hardware products. There are also software applications called Personal Firewalls that you can run on your computer. These Personal Firewall applications monitor all incoming and outgoing communications on your computer as well as what services are trying to interact with what other services. For your computer to be secure, you should have a Personal Firewall installed on it.

Windows XP has a built in firewall. If you are running Windows XP, you can turn on the firewall by going to the Start Menu, click on Control Panel and then Network and Internet Connections, and then Network Connections. Find your internet connection, and right click on it and chose Properties, then click on the Advanced Tab. Make sure the box is checked under Internet Connection Firewall.

For more protection, you should consider purchasing and installing a Personal Firewall from such vendors as Norton, ZoneLabs, Black Ice or McAfee. These Personal Firewalls will give you greater protection than the Windows XP firewall. Before installing Personal Firewall software on a Windows XP computer, be sure that the firewall built into Windows XP is turned off. Never use two software firewalls at the same time. Completely uninstall one before installing another. Use the vendor's uninstall utility or if not available, use the Windows XP add/remove software tool in the control panel.

Some things that a firewall can protect you from include:

• Remote Login: This is when someone is able to connect to your computer and control it is some way, such as being able to view or access your files or being able to actually run programs on your computer.
• Application Backdoors and Operating System Bugs: Some programs and operating systems have special features that allow for remote access or have bugs that provide a backdoor, or hidden access. Experienced hackers can take advantage of these backdoors to gain access to your computer.
• SMTP Session Hijacking: SMTP is the most common method of sending email over the internet. After gaining access to a list of email addresses, a person can send unsolicited junk email (spam) to thousands of users. This is done quite often by redirecting the email through SMTP server of an unsuspecting host, making the actual sender of the spam difficult to trace.
• Denial of Service: Hackers send a request to the server to connect with it and when the server responds, it is unable to find the system that made the request. The hacker inundates the server with these unanswerable session requests, which causes the server to slow to a crawl or eventually crash.
• Email Bombs: An email bomb is a personal attack where someone sends you the same email hundreds or thousands of times until your email system cannot accept any more messages.
• Macros: Macros (scripts of commands that an application can run) created by hackers and loaded on your system can destroy your data or crash your computer.
• Viruses: Viruses are small programs that can copy itself to other computers which allows it to spread quickly from one system to the next. Viruses range from harmless messages to programs that erase all of your data on your computer.
• Spam: Usually harmless, and always annoying, spam is electronic junk mail. Spam can be dangerous, especially when it contains links to web sites. By clicking on the link, you may accidentally accept a cookie that provides a backdoor to your computer.

Other important components of computer security include the following:

• Back Up Your Data Files: You should back up your data files at least once a week, if not daily. If your computer ever crashes, you will be glad you did. Try to put all of your data files into one folder, such as My Documents. This will make backup easier.
• Turn On Automatic Updates: Make sure that the automatic update feature in Microsoft Windows is turned on for "critical updates." Updates, or patches, are needed to fix holes in Windows to protect your security and privacy. To turn on automatic updates, go to Start, My Computer, View System Information, Automatic Updates.
• Select an Internet Service Provider That Filters for Spam and Viruses: Make sure your ISP offers online (server side) virus, spam and content email filters, or use an email service that does.
• Use Anti-Virus Software: Anti-virus software scans your hard disk to find and remove viruses. Most viruses get into your computer through email. Make sure that the software you choose includes an email scanner and that it is compatible with your email software. You should also look for a product that scans your outgoing email for viruses so you don't end up forwarding a virus to your friends and colleagues. Finally, the most important part of you anti-virus software should be that it offers an automatic update service that will check for new virus definitions. Your software will be able to do nothing to stop a new virus if it doesn't have the latest virus definitions.
• Consider Using Other Security and Privacy Software: There are other software products available on the market that you can use to further secure your computer. These products can be used in addition to your firewall and anti-virus software. Anti-Trojan software blocks Trojan horses which is a destructive computer program that masquerades as a harmless application but allows an attacker access to your computer where he can perform almost any action he wants. Anti-Spyware software finds and removes things such as web sites that take over your browser, pop up ads that show up even when your browser has been closed for some time and other malicious software that controls your PC. There are other privacy software products that protect your identity, manage passwords, stop spam, block pop-up ads, and remove temporary files.
• Consider Replacing Microsoft Outlook and Outlook Express With Another Email Program: Propagation of most malicious code (virus, Trojan & worm) is done by email and is designed to take advantage of weaknesses in Microsoft products. Consider switching to another email program, such as Eudora. Eudora is supported by the email scanners of Norton, Panda, McAfee and Trend Micro anti-virus products.

No one security solution will solve everything. The more lines of defense you have in place, the harder it is for hackers to get in and the safer you will be.

Please note that the above information is based on my personal experience. I am not an IT expert. The purpose of this article and other technology articles that I write is to make people aware of situations that exist and possible solutions. Specific questions related to your computer should be directed to your IT consultant. Liberty Professional Services works with a variety of IT consultants on a regular basis if you are looking for a referral.