Distributed Denial of Service Attacks

Distributed Denial of Service (DDoS) attacks areattempts to overwhelm a computer system in order todeny access by legitimate users. They are generallyunstoppable, but there is a good deal of on-goingresearch on methods to reduce their negative effects.This paper will deal with the design of a model thatsimulates such an attack. The simulation model isthen used to study possible ways to defend againstthese attacks. Three experiments are run: 1) using apriority queue to sort messages from clients based onhow many connections they have open on the server, 2)limiting the number of connections each client cancreate, and 3) having the server forcefully deletethe oldest established connection, whenever itsconnection table becomes full. Results show thatmethod 1 is totally ineffective while method 2somewhat improves the overall performance of thesystem. However, method 3, combined with method 2,produces significantly improved performance against aDDoS attack.... Mehr