Sungkyunkwan University Sungkyunkwan University ETRI Korea Telecom Korea Telecom This document describes a framework, objectives, requirements, and use cases for security services based on Software-Defined Networking (SDN) using a common Interface to Network Security Functions (I2NSF). It first proposes the framework of SDN-based security services in the I2NSF framework. It then explains three use cases, such as a centralized firewall system, centralized DDoS-attack mitigation system, and centralized VoIP/VoLTE security system.