What is a firewall? hardware software

What is a firewall?

A firewall is a piece of hardware and/or software that "sits" between your computer and the Internet in order to filter the traffic going back and forth. It acts, as a security checkpoint so that unauthorized data transfer doesn't occur. If this kind of transfer does take place, it could allow a black-hat hacker or a script kiddy to gain remote access to your computer or let a Trojan horse (see Anti-Trojan) exploit your computer. Go Back to Top

How does a firewall work?

When a web page is requested or you are chatting on the Internet, the information is sent back and forth in little envelopes called packets. It works much like our postal system using an envelope with the destination and return information on the outside and the actual letter or data on the inside. This is how information is passed back and forth over the Internet.

The firewall then checks the envelopes and the data to make sure that it is authorized to go to the person it is addressed to and that the person or application sending the data is authorized to use the Internet. For instance, Internet explorer or AOL would be authorized to send data, but a Trojan horse or some other unknown application would be prohibited from doing so until it could be verified why it is using the Internet. Go Back to Top

Why do I need a firewall?

A firewall provides that extra level of protection that you can’t get from an anti-virus program. In fact, the general public regards firewalls the way anti-virus software was viewed during the early 1990’s. At that time, no one would purposely go out and buy the software unless a virus had attacked their computer. The same mistake should not be made with firewalls, because the consequences could be much greater if your computer is exploited.

Some people say, “I don't care if I get hacked, I don't have anything on here anyway.” Well, a hacker may not be interested in your computer directly, but use it indirectly for their criminal purposes. If your computer is hacked, it can be used to gain others and cover the tracks of the hacker, leaving you "holding the bag.”

There really isn't any excuse not have a firewall. There are even some "lite" versions, which are distributed for free and provide adequate protection. However, if you have a high-speed connection (dsl, adsl, or cable) then you need a hardware firewall as well.


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Software Firewalls

A software firewall is a program that examines data packets on a network to deter- mine whether to forward them to their destination or block them. You can use fire- walls to protect only against inbound threats (one-way firewall) or against both unauthorized inbound and outbound traffic (two-way firewall). The standard fire- wall in Windows XP and Windows Vista is a one-way firewall. However, many third-party firewall programs, such as Zone Alarm, are two-way firewalls.

You can configure a software firewall to permit traffic between specified IP ad- dresses and to block traffic to and from the Internet except when permitted on a per-program basis.
Corporate networks sometimes use a proxy server with a firewall as the sole direct connection between the Internet and the corporate network and use the firewall in the proxy server to protect the corporate network against threats.