This book covers the security challenges of software-defined networks and proposes innovative solutions, such as the decentralization of security services and integration with blockchain technology, to enhance software-defined network security. It includes multiple case studies demonstrating the effectiveness of decentralized software-defined network security with three-layered architectures including all application programming interfaces. This book:• Offers in-depth analysis of software-defined network protocols including OpenFlow, Border Gateway Protocol-Link State, and Network Configuration Protocol (NETCONF). • Provides practical guidelines for implementing security measures within software-defined network environments, with a focus on technical aspects like firewall rules, intrusion detection, and access control policies. • Explores how blockchain can be integrated into software-defined networks to enhance security, providing step-by-step technical guidance for implementation. • Discusses supply chain transparency with integration of blockchain and software-defined networks. • Explains blockchain-enhanced network monitoring and control, and implementation of blockchain-secured network communication. It is primarily written for senior undergraduates, graduate students, and academic researchers in diverse fields, including electrical engineering, electronics and communications engineering, computer science and engineering, and information technology.