Classic Denial of Service Attacks

The simplest classical DoS attack is a flooding attack on an organization. The aim of this attack is to overwhelm the capacity of the network connection to the target organization. If the attacker has access to a system with a higher-capacity network connection, then this system can likely generate a higher volume of traffic than the lower-capacity target connection can handle. As shown in the figure the attacker might use the large company’s Web server to target the medium-sized company with a lower-capacity network connection. The attack might be as simple as using a flooding ping  1   command directed at the Web server in the target company. This traffic can be handled by the higher-capacity links on the path between them, until the final router in the Internet cloud is reached. At this point some packets must be discarded, with the remainder consuming most of the capacity on the link to the medium-sized company. Other valid traffic will have little chance of surviving discard as the router responds to the resulting congestion on this link.