A NAT traversal mechanism for cloud video surveillance applications using WebSocket

This paper describes a novel Video Surveillance as a Service (VSaaS) architecture. The proposed solution uses an add-on component, named WS-Gateway (WebSocket-based gateway), installed in the client’s private network (along with IP-cameras network). The WebSocket protocol is used to establish a bi-directional communication among the actors in the system. The main advantage of the solution is the overcoming of reachability problems caused by the presence of NATs or Firewalls in the network. A prototype system including one IP-camera, a WS-Gateway running on Android smartphone, a WS-Server built on a Windows system, and a Web-page implementing an user front-end has been tested. The obtained experimental results are compared, in term of latency time, frame loss rate and other implementation features, to other existing solutions, and to the traditional HTTP-Polling used in conjunction with the SSH reverse tunneling to traverse the NAT.