Denial of service attacks are designed to lock out legitimate users from web sites or networks. Hackers run programs that repeatedly request information from the victim's computer until that computer is unable to answer any other requests. Hackers can run programs of automated scripts that barrage the victim computer or network so that it becomes unusable by legitimate users, or even has to be shut down.

Distributed denial of service attacks (DDoS) are automated attacks that run simultaneously from multiple computers. Hackers can plant Trojan horse programs on the computers of unsuspecting accomplices throughout the network or internet. At a given hour, all involved computers coordinate requests for information from the overloaded victim computer. Due to the numbers involved, such an attack can be very difficult to stop.

Most Hacking is done as "An inside Job". A hacker may pose as an employee who forgot his or her password, or a software vendor asking for information about a network in order to determine what the company's software needs are. By gaining or establishing trust a hacker can infiltrate your system by getting you to give them a key!

Trojans horse programs are "back doors" into a computer system. A hacker may disguise a trojan as another program, video, or game, in order to trick a user into installing it on their system. Once a trojan is installed, a hacker could have access to all the files on a hard drive, a system's email, or even to create messages that pop up on the screen. Trojans are often used to enable even more serious attacks. By hiding programs to be run later, hackers might gain access to other networks. The simplest Trojan horse replaces the messages shown when a login is requested. Users think they are logging into the system, so they provide their usernames and passwords to a program that records the information for use by the hacker. The most famous Trojan horse to date is probably Back Orifice, once installed, this program gives the user access and control over any computer running a Windows 95/98 operating system or later.

Worms and viruses are surreptitiously "self-replicating" programs that can spread exponentially throughout a network. Modern-day virus writers often have malicious intent, however, and they use viruses and worms to spread destructive programs among unwitting hosts. A virus spreads by infecting another object on the computer system--a program file, a document, or the boot sector of a floppy disk. A worm can copy itself from computer to computer on a network without needing a file or other object. The most famous worm was the ILOVEYOU bug, which infected an estimated 45 million computers. It propagated itself by exploiting a weakness in the Microsoft Outlook email software, and emailing itself to every address stored in the Outlook address book on an infected computer.

Close and lock the door, then don't give out keys to strangers... Anytime you are connected to the Internet you are assigned an IP address. This is your door, if it is open anyone can come in without you knowing it. the simplest protection is a utility that blocks intruders and alerts you. Most of these can be downloaded free on the internet and offer minimal security. Personal firewall software can be effective, but at times confusing to set up and a separate copy is required for each machine. The most effective firewall is a hardware device. It can be a separate computer with two network cards installed and proxy software. The important thing is having two network cards or MAC addresses, forcing network traffic through the proxy software. Another solution is a stand alone firewall device between your computer, or network and the Internet. these devices have drastically dropped in price recently and can be purchased for under $200.00.

Most of the time hackers have permission to compromise your system because you let them in. Even though the door is closed and locked, a friendly face can still get in! Email Viruses, Trojan horses, or Downloading files can compromise your system. Reputable virus scanning software is required protection. Virus data files must be kept up to date, a personal example... I have a virus scanning program installed on my computer, I went a month without updating the Virus Data files. When I did update I found I had 150 files infected with a malicious worm virus that was about to do serious damage to not only my hard drive but also my system bios. New viruses surface every day, prevention is the key. Common sense is the best protection, a door can only be locked and secure if you don't give out the key.

• Change your passwords frequently, and don't share your passwords with anyone.
• Be cautious while on the internet, don't open a back door to your system.
• Keep the door locked.

http://www.pbs.org/wgbh/pages/frontline/shows/hackers/

http://www.firewall.com/

http://www.firewallguide.com/

http://www.robertgraham.com/pubs/firewall-seen.html

http://www.vicomsoft.com

http://www.cvsweb.com