  With the proliferation of new technologies such as Internet of Things (IOT)
and Software-Defined Networking(SDN) in the recent years, the distributed
denial of service (DDoS)attack vector has broadened and opened new
opportunities for more sophisticated DDoS attacks on the targeted victims. The
new attack vector includes unsecured and vulnerable IoT devices connected to
the internet, denial of service vulnerabilities like southbound channel
saturation in the SDN architecture. Given the high-volume and pervasive nature
of these attacks, it is beneficial for stakeholders to collaborate in detecting
and mitigating the denial of service attacks in a timely manner. The blockchain
technology is considered to improve the security aspects owing to the
decentralized design, secured distributed storage and privacy. A thorough
exploration and classification of blockchain techniques used for DDoS attack
mitigation is not explored in the prior art. This paper reviews and categorizes
the existed state-of-the-art DDoS mitigation solutions based on blockchain
technology. The DDoS mitigation techniques are classified based on the solution
deployment location i.e. network based, near attacker location, near victim
location and hybrid solutions in the network architecture with emphasis on the
IoT and SDN architectures. Additionally, based on our study, the research
challenges and future directions to implement the blockchain based DDoS
mitigation solutions are discussed. We believe that this paper could serve as a
starting point and reference resource for future researchers working on denial
of service attacks detection and mitigation using blockchain technology.
