NAT穿越模块的设计与实现，NAT实现了公网地址和内网地址之间的映射，可从两个方面来概括：(1) 当内网内的IP包经过NAT需要流入公网时，NAT将此IP 包的源IP地址和端口改为NAT接口上的一个公网地址和端口；(2)当公网中的IP包经过NAT 需要访问内网资源时，NAT将此IP 包的目的地址和端口改为内网IP 地址和端口-NAT through the Design and Implementation of Module, NAT a public network address and network address mappings between, can be summed up in two ways: (1) within the network when the IP packets through NAT, when the need for inflow of the public network, NAT this IP packet　s source IP address and port on the interface changed to NAT a public network address and port　(2) When the public IP network packets through NAT need access to resources within the network, NAT to IP packet destination address changed within the network and port IP address and port