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I have the following example:

From my understanding of static NAT the client makes a request on the inside global address of a resource, in this case the webserver. (http://209.165.201.5). The request then gets translated into the inside local address at R2. (209.165.201.5 is translated to 192.168.10.254)

However in this example the NAT inside is assigned IP address 10.1.1.2 255.255.255.252 and the outside is assigned 209.165.200.225 255.255.255.224.

How is NAT supposed to work in this scenario?

Static NAT example

1 Answer 1

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Destination NAT translates an outside address to an inside address. Often that's one of the router's addresses.

(I'm ignoring TCP's intricacies here and am just using "request" as a high-level concept.)

  1. The client sends a request to TCP 209.165.201.5:80.
  2. The request is received by R2's S0/1/0.
  3. R2 translates the request's destination to TCP 192.168.10.254:80 due to its static NAT configuration.
  4. The router forwards the request out of its S0/0/0 interface, according to its routing table entry for 192.168.10.254.
  5. Subsequent routers forward the request to the web server.
  6. The process reverses for the server's reply.
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  • But in this example the interface S0/1/0 has IP address 209.165.200.225. This wouldn't work right?
    – Rubus
    Commented Jan 7, 2023 at 12:06
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    Why not? As long as the destination 209.165.201.5 is routed into that interface, the interface's own IP address is irrelevant.
    – Zac67
    Commented Jan 7, 2023 at 13:01

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