Monday, April 4, 2011

Why would you need a Firewall

First, most people frequently store information, such as e-mail, spreadsheet database, and even passwords to online accounts (eBay and PayPal, for example) on their computers

This figure shows how a hacker can start what is called a brute-force attack to gain access to one of your computers. Tools to perform such attacks, which are easily available on the Internet, use dictionary files to constantly attempt to guess your password to remotely log in to your computer or to access a shared drive.

If left unrestricted, hackers can attempt thousands of times until they are successful. When into the computer, they can basically help themselves to whatever information you have stored there.

In the second example, it is not the information itself on the computers the hacker is interested in, but enrolling your computer (probably together with hundreds or thousands of others) into what is called a zombie army. Zombie armies are when a hacker has taken over control of a lot of computers and then uses the computers for illegal means, such as to attack other computers or business websites.

Next figure shows an example of using a bot army to carry out a distributed denial-of-service (DDoS) attack.

By exploiting a security flaw in the computer's operating system, hackers can install a little program to take remote control of your computer. After doing so on hundreds or thousands of other computers, hackers can then go after their target with a DDoS attack by instructing all the remote-control computers in the zombie army to start sending web page requests to a website such as and repeat the requests as often as possible.

If successful, the tens of thousands of requirements can cause a spike in the web server and possibly cause it to fail because of overloading. If they cannot cause the server to fail entirely, it might be possible to disrupt or slow down the service to legitimate folks who are trying to access the website.

This is called a DDoS attack. If the attack were carried out from a single computer, the website owner might be able to identify a model and simply block that computer from making subsequent requests. On the other hand, if the attack is coming from thousands of people's home computers, how can the website owner differentiate legitimate requests from an attack? That's the point of a bot army: scale, anonymity, and stealth.

We do not make-believe to have the answers to why people do things like that. Quite frankly, many of them are highly clever folks, who for whatever reason have decided to run against society's grain. Regardless of why, they do it; so, it is important for you not to be a victim.

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