The salient features of cloud computing (such as on-demand self-service, resource pooling, broad network access, rapid elasticity, and measured service) are being exploited by attackers to launch the severe Distributed Denial of Service (DDoS) attack. Generally, the DDoS attacks in such an environment have been implemented by flooding a huge volume (high-rate) of malicious traffic to exhaust the victim servers’ resources. Due to this huge volume of malicious traffic, such attacks can be easily detected. Thus, attackers are getting attracted towards the low-rate DDoS attacks, slowly. Low-rate DDoS attacks are difficult to detect due to their stealthy and low-rate traffic. In the recent years, many efforts have been devoted to defend against the low-rate DDoS attacks. By utilizing the salient features of cloud computing, it becomes easy for an attacker to launch sophisticated low-rate DDoS attacks. Thus, the study of various DDoS attacks and their corresponding defense approaches becomes essential to protect the cloud infrastructure from fatal effects of DDoS attacks. This paper presents a comprehensive taxonomy of all the possible variants of cloud DDoS attacks solutions with detailed insight into the characterization, prevention, detection, and mitigation mechanisms. The paper provides a detailed discussion on essential performance metrics to evaluate various defense solutions and their behavior in a cloud environment. The purpose of this survey paper is to excite the cloud security researchers to develop effective defense solutions against the various DDoS attacks. The research gaps and challenges are found, and described in the paper while future research directions are outlined.

中文翻译：

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云计算环境中针对 DDoS 攻击的防御机制：最新技术和研究挑战

攻击者利用云计算的显着特征（如按需自助服务、资源池化、网络广泛访问、快速弹性和可测量服务）发起严重的分布式拒绝服务（DDoS）攻击。通常，这种环境下的DDoS攻击都是通过大量（高速率）的恶意流量泛洪来耗尽受害服务器的资源来实施的。由于恶意流量如此巨大，此类攻击很容易被检测到。因此，攻击者逐渐被低速率 DDoS 攻击所吸引。低速率 DDoS 攻击由于其隐蔽和低速率的流量而难以检测。近年来，针对低速率 DDoS 攻击的防御投入了大量精力。利用云计算的显着特点，攻击者很容易发起复杂的低速率 DDoS 攻击。因此，研究各种 DDoS 攻击及其相应的防御方法对于保护云基础设施免受 DDoS 攻击的致命影响至关重要。本文对云 DDoS 攻击解决方案的所有可能变体进行了全面分类，并详细了解了特征、预防、检测和缓解机制。本文详细讨论了评估各种防御解决方案及其在云环境中的行为的基本性能指标。本调查论文的目的是激发云安全研究人员开发针对各种 DDoS 攻击的有效防御解决方案。发现研究空白和挑战，