With the trend of developing more and more applications for Unmanned Aerial Vehicles (UAV), several research projects have considered new missions where single UAVs are replaced by swarms of drones. Although today regulations do not take into account such scenarios, implementation of an efficient security policy appears mandatory before operating a swarm of drones in open spaces. Consequently, this paper introduces an architecture for providing security features through the use of software defined network (SDN) technologies. To validate our approach, we compare the routing performance of our architecture with a classical solution based on the AODV routing protocol and the use of iptables rules. The results confirm the suitability of a SDN solution in this context. Finally, we present how it may be used to improve network security for a swarm of cooperative drones.