说明：  STUN演示程序源码，能穿过绝大多数防火墙NAT等.演示实际际应用中的VOIP上UDP通信体系 可直接使用。 已通过测试。
(STUN demo program source code, can pass through most firewalls and NAT applications demonstrates the actual occasion of VOIP UDP communication system can be used directly. Has been tested.)