The IEEE Software Defined Networks' eLearning Module "An Introduction to Software Defined Network Security" is the first of two modules and gives an overview of the subject with a quick reminder of Software-Defined Networking (SDN) and on the Openflow protocol. Then, the session will provide an introduction to a policy model based security framework that is a great fit to SDN. This presentation will also feature the new risks that SDN introduces and how to mitigate those. And lastly, a recent security concept named Software Defined Security where SDN and Network Function Virtualization (NFV) meet.