Denial of Service Attacks

Availability requires that computer systems function normally without loss of resources to legitimate users. One of the most challenging issues to availability is the denial-of-service (DoS) attack. DoS attacks constitute one of the major threats and among the hardest security problems in today’s Internet. The main aim of a DoS is the disruption of services by attempting to limit access to a machine or service. Depending on the attackers’ strategy,the target resources may be the file system space, the process space, the network bandwidth, or the network connections. These attacks achieve their goal by sending at a victim a stream of packets in order to exhaust the bandwidth of its network traffic or its processingcapacity denying or degrading service to legitimate users. There have been some large-scale attacks targeting high-profile Internet sites