Do you have passwords, love letters, naughty pictures or sensitive business information stored on your computer's hard drive? If you have a continuous Internet connection such as cable, xDSL, ISDN or other, you should know that it's almost embarrassingly easy for a hacker to break into a networked computer.
Once in, they can use your private information any way they see fit. As well as getting your personal documents, hacker can damage your system files or install software on your disk that allows your computer to be used in Denial of Service attacks and other destructive activities.
Similarly, hacker can activate your interior microphone or interior video recorder without your knowledge. This lets them record and distribute sound and video files of conversations and activities taking place in your work area.
How Hackers Do It Every Internet-connected computer has a unique set of identifying numbers called an IP address. Using special software applications, hackers send out probes over Internet looking for live IP addresses. If they locate your computer, they look for "holes" or vulnerabilities that leave your system insecure.
For example, a computer is likely to have multiple applications (email, web browser, etc.) running on same IP address. Each application is assigned a number called a "port" that uniquely identifies that service on a computer. Ports that allow an application to send or receive information from Net must be "open". In some unprotected systems, even ports that are not in use have been left open -- practically inviting attack! When hackers discover an unprotected, open port, they can use that opening to gain access to your system.
An unprotected broadband connection is easiest to hack because both connection and IP address remain constant. If a hacker or a "script kiddie" finds your computer once, they can readily find it again. (Script kiddie is a derogatory name used by professional hackers to describe simple scripts used by young and inexperienced hackers).
The threat is less severe for persons connecting to Internet via dial-up modems. Dial-ups usually connect with a different IP address each log-on. Therefore, if hackers have found a system once, changing IP address will make it difficult (not impossible) to find it again.
However, if a trojan horse or back door program has been installed on a system, trojan horse could "phone home" with IP address each time an Internet connection is made.
Back door programs allow remote users to control a system without owner's knowledge. They are installed on computers by hackers, or sometimes come secretly bundled with software applications that user installs. Well-known back door programs for Windows computers include BackOriface, NetBus and SubSeven.
Firewalls: Your First Level of Security Firewalls are software applications or hardware devises that you install on your system. They are designed to prevent unauthorized access to or from a private network that is connected to Internet. When a firewall is installed, all incoming or outgoing messages pass through firewall. Those that do not meet specified security criteria are blocked.
Most home firewalls are software applications.
How Firewalls Work There are various types of firewalls, and they work through different processes. However, following is true for most of home or personal firewall software that is used today.