The major way of contact in today's landscape of interconnected global commercial
activities occurs via cloud-based networks that transcend national, geographic, and
jurisdictional barriers. Software Defined Networking (SDN), a developing networking
architecture meant to ease policy enforcement and dynamic network reconfiguration,
enables this seamless integration. Even with all the obvious advantages brought in by SDN,
the problem of larger attack surface size compared to traditional networking infrastructures
cannot be considered minor, particularly within the context of safety-critical applications.
This problem gets even more exacerbated if SDN has to handle networking features relevant
to the IoT. In particular, such deployments are more vulnerable to certain types of attacks.
Added to that is the increasing need for inter-cloud communications in IoT applications,
creating a nightmare from the security point of view. Furthermore, the number of connected
nodes significantly complicates the situation and creates an overwhelming barrier toward
monitoring all entities to prevent system degradation and service disruption. The paper aims
to provide a general overview of frequent security challenges concerning SDN and IoT
cloud integration, going deeper into the basic design concepts of the newly established
paradigm called Blockchain, which could be considered a critical security aspect in each
SDN or IoT application. Given the peculiar features of the paper, it proposes a Blockchain
implementation solution to help nullify and minimize the various security issues which
come about due to the convergence of SDN and IoT.