Abstract
The use of cloud computing has increased significantly in recent years; therefore, many cloud platforms have become in demand such as OpenStack, AWS etc. One of the challenges in cloud computing is providing secure and reliable services. For the last few years, Denial of Service (DoS) and Distributed Denial of Service (DDoS) attacks are the biggest threats in cloud security. DoS and DDoS attacks are initiated by the hacker to make an online service occupied by compromising it with massive traffic from multiple sources. The aim of this paper is to study the impacts of several types DoS/DDoS attacks in the cloud, and the procedures that they use to affect the services' availability. Furthermore, several mitigation techniques are discussed as well. To achieve this study, research and simulation work has been done.