Abstract: This paper introduces a lightweight, decentralized security framework for the Northbound Interface (NBI) in Software-Defined Networking (SDN), leveraging blockchain technology to overcome the limitations of centralized architectures. Traditional access control mechanisms in SDN suffer from single points of failure, low scalability, and vulnerability to REST API abuse. The proposed framework distributes security functions across multiple blockchain peers, eliminating the need for compute-intensive consensus algorithms while maintaining data immutability and trust. The system enforces access control via token-based authentication, policy validation, and a dynamic trust model. Experimental evaluation shows minimal performance impact, with an average overhead of 0.174 seconds for read and 0.121 seconds for write operations, and <0.25 KB packet overhead. The architecture effectively mitigates common STRIDE threats and supports real-time, resilient NBI protection. These results confirm the proposed solution as a scalable and secure alternative for modern SDN environments.

Keywords: Software-defined network, Northbound interface, Blockchain technology-based, Decentralized access control system, Security, Scalability, Decentralization

Pages: 42-57