NATMap 实现与拥有动态公网 IP 同等的访问效果，它通过打通完全锥型(Full cone)类型NAT的TCP、UDP端口，实现任意主机在无需客户端的情况下进行直连访问。

There are four core types of NAT:

• Full Cone NAT: Any external address and port may access an internal resource as long as the internal resource is contacted first
• Restricted Cone NAT: An external IP address can connect to an internal resource only if it has previously interacted with it
• Port Restricted Cone NAT: Only if an external IP address and port has interacted through that port with the internal resource it has the accessibility on the external address and port
• Symmetric NAT: When packets are sent to an external IP address and port, while being replied from the same, different handles will be provided to the external IP address and port. When two different outside users attempt to connect to the same internal address with the same port number, each will receive a different number