Intelligent Transportation Systems (ITS) are systems deployed to optimize the road traffic and realize safe, efficient and comfortable human mobility. Cooperative ITS is a new vision of ITS where vehicles, the roadside infrastructure, traffic control centers, road users, road authorities, road operators, etc. exchange and share information based on a common communication architecture -- known as the ITS station reference architecture -- supporting all types of ITS use cases over a diversity of access technologies (11p, 11n, 3G/4G, infra-red, ...). The building blocks of the ITS station are specified within ISO, ETSI, IETF and IEEE. To promote the deployment of Cooperative ITS and to encourage further research on it, we introduce an open-source software combining IPv6 and GeoNetworking which are two essential building blocks of the ITS station. It comprises the GeoNetworking protocol, the GN6 adaptation sub-layer (GN6ASL) and the test tools of Basic Transport Protocol (BTP). We implemented each module separately to facilitate the analysis and modification of the protocol behavior and provided a library for inter-process communication between the modules to allow extensibility. Our participation to Cooperative ITS plug tests organized by ETSI demonstrates that our implementation complies to the Cooperative ITS standards while a basic performance evaluation shows that overhead from our implementation design is limited.