This document discusses the implementation of a unified security plugin for the Opendaylight SDN controller. It begins by describing how SDN architectures introduce new security challenges by making the controller a single point of failure. It then outlines some existing security measures in Opendaylight but notes remaining vulnerabilities, such as from packet-in flooding attacks. The document proposes a unified security plugin that would monitor the controller's interfaces and APIs to identify attacks and share security-related information for mitigation. It provides an example of how the plugin could help detect and block a packet-in flooding attack aimed at overwhelming the controller.