An attack characterized by an explicit attempt to prevent legitimate users of a network service from using that service. The most common method is to flood a network with useless traffic, overloading the network's capacity. Other DoS techniques include disruption of the connection between two machines and malicious alteration of server configuration. Many variants, such as the Ping of Death and Teardrop, exploit limitations in the TCP/IP protocols. For all known attacks, there are network security fixes that system administrators can install to limit damage. But, like viruses, new incarnations are constantly being dreamed up by hackers.