Programmable firewall using Software Defined Networking Software Defined Networking is an exciting technology that enables innovation and flexibility in designing and managing networks, but it also introduces new security issues. Our Major challenge is to build powerful and flexible firewall applications for protecting software defined based networks. In this paper we focus on designing and developing OpenFlow based firewall application. The implementation shows that most of the firewall functionalities can be built using software, without need of dedicated hardware. We are using open source POX Controller based on python for our experiments. To perform experiment, we have used VMPlayer virtualization solution and installed Mininet emulator for creating network topologies. In this paper, we present the implementation details as well as experimentation results of firewall application.