Network security is a predominant topic both in academia and industry. Many methods and tools have been proposed but the attackers are still able to launch massive and effective attacks. Keeping the pace with the new threats appearing or becoming more sophisticated everyday is of a paramount of importance. Software Defined Networking (SDN) has recently emerged and promotes the programmability of the networks, which thus allows to enable in-network security functions. This includes firewalls, monitoring applications or middlebox support through OpenFlow devices. Therefore, this paper reviews the related approaches which have been proposed by identifying their scope, their practicability, their advantages and their drawbacks.