Every computer that connects to the internet in any form MUST have a firewall
Each computer must have a personal firewall or be behind a corporate firewall. The type of connection to the internet is not important. A personal or corporate firewall is required for dial in connections, cable modem, DSL, ISDN, T1 and others. The ONLY exception is when there is some type of firewall already existing between the computer and the internet. Get a personal firewall and configure it according to the maker’s instructions.
Why do I need a firewall?
It would seem that if you keep your anti-virus definitions update with your virus protection program and you keep your system patched with the latest updates you would not need a personal firewall. Viruses would be immediately caught by your antivirus program, and your vulnerabilities would not exist since you always patch them immediately. This does not work for the following reasons:
Viruses begin to spread before they are identified. The only way they are identified is when someone discovers their computer is behaving incorrectly and then they realize they have a virus. Then the virus updates are posted to anti-virus vendor websites such as Symantec. Therefore the virus can spread to you before it is identified and your system may be compromised and other unwanted items such as hacker backdoors may be placed on your system before the virus is removed. A firewall can also help prevent additional malware from being placed on your system if you should get an unknown virus.
Firewalls typically block most of the routes that viruses, trojans, worms, and hackers will try to use to gain access to your computer. A computer with a firewall is thereby much better protected than one without.
It is likely that some vulnerabilies may not be patched before an attack occurs. Firewalls can stop these attacks from being successful.
Vulnerabilities like viruses must also be discovered. If a hacker discovers the vulnerability or someone writes a virus program to use an undiscovered vulnerability, a firewall may still be able to prevent the attack.
Even with all these measures there is no guarantee that your system cannot be compromised by a virus, worm, or hacker, but it is very likely that you will have much less trouble. Remember there is no guarantee that your hard drive will not break tomorrow so you should also back up your data to another computer, tape, or CD periodically when possible.
To determine the best firewall, check the firewall products section to see a variety of firewall products. Read firewall product reviews on this site and other sites. You may be able to find more personal firewall reviews by going to Google and typing “personal firewall reviews” to find sites that provide these reviews. If you cannot afford a firewall, there is a version of zonealarm personal firewall which is free for individuals and non profit organizations. It is available at http://www.zonealarm.com Please do not violate license laws when using this product. Since antivirus software is also an essential requirement to have a reasonably secure computer, several products out today combine the personal firewall with their anti-virus software.
Configure your firewall before connecting to the internet. Most users should at this point read their documentation or run the provided firewall tutorial. You may get alerts while configuring or in one case I got an alert indicating that a specific program wanted to act as a server on the internet. Before answering the question I used another computer and went to https://www.Google.com and looked up the name of the program the alert had specified. At this point I realized the computer had a virus. If you are told by the alert that a program wants to act as a server the likely answer to this question should be no, but it is best to look up the program name on Gigablast to be sure. Also be aware of any actions you may be taking which may cause a program to access the internet to help determine whether an action you took caused the internet access request to occur.