Monday, June 13, 2011

Firewalls–First Layer of Defense

A firewall is a wall or barrier that is designed to block malicious or unauthorized access while allowing legitimate traffic though a network. Firewalls can be either software or an actual dedicated hardware device. Dedicated hardware firewalls tend to be more robust and are often used in businesses, but for most home computer users a software firewall will suffice.  Also many home routers will have some form of a firewall built in.  Most modern operating systems include a firewall, including Windows XP, Vista, and 7. Windows XP’s firewall is slightly lackluster, but should be sufficient.

A firewall is more for protection against hacking or malicious access than protection against viruses.  For this reason, just because you have a firewall, do not expect it to protect you against a virus.  In the security world, layered protection is the best protection method and a firewall is usually the first layer at the entrance of a network or a computer.

One of the keys to a firewall is minimizing the number of holes (doors or windows) in the wall.  A hole in a computer firewall can be an open port such as FTP port 21.  You will not be able to close every port in your firewall (if you did you would be better off just pulling the cable on the back your computer – which actually might not be a bad idea now days!), but be sure not have services selected that you will not be using!  In the screenshot below you can see a number of services that Windows has turned off (blocked).

windows-firewall-rules-allow-a-program

If you have Windows XP, Vista, and 7 you should be all set for a firewall, and of course many security suites also come with a firewall.  One thing that you will probably see no matter what firewall program you use is a request to allow a program through a firewall.  What should do when you see this?  That depends greatly on what you are doing, if you just opened a program such as an instant messaging application for the first time (or the instant messaging application updated itself) then the the firewall popup most likely has to be for the instant messaging application; of course, try to verify that is the case be looking at the details given in the popup.  Hopefully the popup will list the program name as well as the location it is running from.

Now of course with all that being said about a firewall, one of the single most important items with a firewall is to make sure it is ON!  Sometimes you may be required to temporarily disable a firewall if that is the case make sure you enable the firewall when done!  If you are using the Windows firewall, it should notify you if it is off.

Windows-7-Firewall

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