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防火墙的NAT(Network Address Translation)功能已经使互联网具备了与汽车上“没有无线电设备”标记同等的含义:两者部告诉入侵者不要轻易破门而入,因为没有东西可偷。为从外部保护企业主机和系统的真正IP地址和身份,多数防火墙要把内部网络地址转换为多个外部地址(有时转换为单个外部地址)。对一个基于Internet的局外人来说,它看起来就好象是网络上只有一台主机。防火墙在挫败入侵者闯入企图方面作了特殊设计。如果你的网络使用了一个为专有网络保留的特殊IP地址,NAT对Internet连接就显得十分重要。这些地址不能由Internet路由器进行路由选择,所以在它们离开一个专用网络之前必须把它们转换为“真实”地址。
The NAT (Network Address Translation) feature of the firewall has given the Internet the same meaning as the “no radio” mark on the car: both tell the intruder not to break into it easily because there is nothing to steal. To protect the true IP address and identity of the corporate host and system externally, most firewalls translate the internal network address to multiple external addresses (sometimes translated to a single external address). For an Internet-based outsider, it looks as if there is only one host on the network. Firewalls have been specially designed to thwart intruders’ attempts to intrude. If your network uses a special IP address reserved for the private network, NAT Internet connection becomes very important. These addresses can not be routed by Internet routers, so they must be translated to “real” addresses before they leave a private network.