NAT Static Address Translation

Basic NAT Static Address Translation shows an example of a basic static NAT address translation. The three addresses that take part in this basic static NAT example can be either IPv4 or IPv6, but they can not be a mix of the two IP address types. The three example addresses are:

• The Client1 internal private network IP address
• The Server1 external public network IP address
• The statically configured external public network IP address

A static NAT translation is configured that maps the Client1 IP address to a publicly addressable static outside IP address.

A packet arrives at the NAT router from Client1 with a source address of Client1 IP address and a destination address of Server1 IP address. The packet leaves the NAT router with a source address of the public static IP address and a destination address of Server1 IP address. The IP packet's destination address is not changed, only the source IP address is changed. Server1 receives the packet from the NAT router with no knowledge of the internal private network Client1 IP address.

When Server1 responds to Client1, the packet arrives at the NAT router with Client1‘s translated public static IP address as the destination address, but leaves the NAT router with Client1‘s actual internal private network Client1 IP address as the destination address. The NAT router delivers Server1‘s response to the Client1 IP address.