The outbound SYN packet from each host creates the necessary NAT state for its own NATs.

从各自的主机外出的SYN包，为他们自己的NAT产生可能的NAT状态。

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NAT would do network address translation for outbound packet so that inside hosts can use reserved IP addresses and outside hosts can not visit inside ones directly to realize one-way communication.

NAT对内网主机的出网数据包进行网络地址变换，内网主机可以使用保留地址上网，外网主机无法直接访问内网主机，从而实现单向通信。

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Port prediction allows a host to guess the NAT mapping for a connection before sending the outbound SYN and is discussed in detail later.

端口预报允许一个主机去猜测NAT映射，找到一个在发出外发的SYN包的连接，这个在之后还会讨论到。

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