Software-Defined Network (SDN) is vital in simplifying the dynamic network characteristics and device management. However, the centralized architecture of SDN opens the scope for malicious attacks on the controllers. To mitigate such attacks in real-time, we propose an SDN architecture for resourceconstrained devices in a fog-enabled IoT environment using a private blockchain (pBC) network. We exploit the decentralized nature of pBC for enabling resource-constrained SDN controllers towards transparently setting flow rules for fog nodes and other devices in the network. In case the miners identify faulty flow rules, pBC allows the SDN devices/fog nodes to retract back to an earlier flow rule while raising a flag against the alleged controller. Additionally, since data in pBC are accessible by all the candidates having the same genesis file, they are readily available to malicious users. Towards this, we further propose encrypting the data before inserting them into the blocks, which helps in securing the data from undesired users. Through the extensive deployment of our proposed fusion, we observe CPU usage of 30% among the devices and latencies in the range of milliseconds, which presents the feasibility of our system with minimum delay. We also observe a reduction in energy consumption by more than 90%, compared to traditional SDN.

The proliferation of IoT in various technological realms has resulted in the massive spurt of unsecured data. The use of complex security mechanisms for securing these data is highly restricted owing to the low-power and low-resource nature of most of the IoT devices, especially at the Edge. In this work, we propose to use blockchains for extending security to such IoT implementations. We deploy a private Ethereum blockchain consisting of both regular and constrained devices connecting to the blockchain through wired and wireless heterogeneous networks. We additionally implement a secure and encrypted networked clock mechanism to synchronize the non-real-time IoT Edge nodes within the blockchain. Further, we experimentally study the feasibility of such a deployment and the bottlenecks associated with it.We study the effects of network latency, increase in constrained blockchain nodes, data size, Ether, and blockchain node mobility during transaction and mining of data within our deployed blockchain. This study serves as a guideline for designing secured solutions for IoT implementations under various operating conditions such as those encountered for static IoT nodes and mobile IoT devices.