RDMA has been widely adopted as a promising solution for high performance networks, but is still unavailable for a large number of socket-based applications running in public clouds due to the following reasons. There is no available virtualization technique of RDMA that can meet the cloud's requirements. Moreover, it is cost prohibitive to rewrite the socket-based applications with the Verbs API. To address the above problems, we present vSocket, a software-based RDMA virtualization framework for socket-based applications in public clouds. vSocket takes into account the demands of clouds such as security rules and network isolation, so it can be deployed in the current public clouds. Furthermore, vSocket provides native socket API so that socket-based applications can use it without any modifications. Finally, to validate the performance gains, we implemented a prototype and compared it with current virtual network solutions against 1) basic network benchmarks and 2) the Redis, a typical I/O intensive application. Experimental results show that the latency of basic benchmarks can be reduced by 88% and the throughput of Redis is improved by 4 times.