232 Copyright © 2019, IGI Global. Copying or distributing in print or electronic forms without written permission of IGI Global is prohibited. Chapter 11 DOI: 10.4018/978-1-5225-6023-4.ch011 ABSTRACT The future networks are expected to lead a hyper-connected society with the promise of high social and economic value. The goal is to solve today’s network problems and provide satisfactory security. Thus, the future networks require a fexible infrastructure that is secure against cyberattacks. Software defned networking (SDN) can be considered as one of the building blocks of upcoming networking technolo- gies. In this chapter, frst, the limitations of today’s networks are presented. Then, solutions to secure the networks with SDN components are given. This concept is referred to as “SDN for Security.” While SDN facilitates securing networks in general, it introduces additional challenges, mainly, the vulner- abilities of the SDN components such as the controller have to be addressed. Security for SDN aims at securing SDN assets and is discussed in the sequel. After reading this chapter, readers will obtain a comprehensive overview of the limitations of traditional networks, such as how SDN overcomes those limitations and the security issues thereof. Software-Defned Network Security Ahmed Demirpolat Middle East Technical University, Turkey Doğanalp Ergenç Middle East Technical University, Turkey Esref Ozturk Middle East Technical University, Turkey Yusuf Ayar Middle East Technical University, Turkey Ertan Onur Middle East Technical University, Turkey