Denial of service attacks are the most recent form of computer attacks which aim to hinder or destroy e-commerce and e-business being done on the Internet. Denial of service is when attackers try to stop or disrupt legitimate users from accessing information from a certain resource. Put simply it is when an attacker intentionally tries to stop visitors from visiting a website. There are four main types of denial of service attacks. The first is a flood attack. A flood denial of service attack is where attackers hog the bandwidth to a certain site so that no other visitors can go through. The second type of denial of service attack is when a connection between two machines is interrupted thereby limiting services.

The third type of denial of service attack is stopping a specific user from accessing a service, and the fourth type of denial of service attack is when a service is denied to a specific user. How are Denial of Service Attacks done? The most common way is to consume limited resources like bandwidth so that no others can use it. Another common way is to fill up disk space with garbage information so that the computer or server can not function. The less common but more dangerous way is when the attacker alters configuration data so that the computer will not function correctly or even open up other security holes. Recently this was done to over 750 western websites by Islamic extremist who were protesting a military action.