What is a firewall? Where is it used? Why is it necessary?

Subject E-Commerce
NU Year Set: 2.(d) Marks: 3 Year: 2012

In computing, a firewall is software or firmware that enforces a set of rules about what data packets will be allowed to enter or leave a network. Firewalls are incorporated into a wide variety of networked devices to filter traffic and lower the risk that malicious packets traveling over the public internet can impact the security of a private network. Firewalls may also be purchased as stand-alone software applications.

The Internet has provided the ability to connect any computer, anywhere, to any other computer, anywhere. It is great fun to surf the vast internet visiting one website after another (effectively connecting with one computer after another) in search of useful information, entertainment, connecting people, and doing a variety of things. However, being connected to the internet also has associated risks from perpetrators who are out there to cause damage. Any computer or device connected to the Internet that is not properly protected is vulnerable to a variety of malicious intrusions and attacks. This applies to all users of cable modems, digital subscriber lines (DSL) and dial-up lines. Cable modem and DSL users are more vulnerable because both connection methods provide always-on connection capability. The likelihood of a malicious person entering your computer increases significantly the longer your computer is on and connected to the Internet.

You would normally think that if you have installed an anti-virus software, you are secure. While anti-virus software does protect you from viruses, spyware and malware, they have their own limitations. If you have a single computer to protect, you can install an anti-virus software that has an in-built personal firewall, and you are fairly secure. Off course, you need to configure your personal firewall software to block unwanted access to your computer from the outside network.

If you have a network of computers, be it a home network or an organization's network, you need to consider setting up a firewall. In this article, I will provide an overview of what a firewall is, and provide a conceptual understanding of the subject. My discussions are primarily centered around small organizational networks and are more relevant for IT heads and security managers. However, as an individual to you can benefit from the knowledge you will gain.

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