NAT Is About Hiding or Changing the Truth About Source Addresses

It is really true: Lying is what NAT does for a living. Let’s look at Figure 14.1. The two users are using private address space on the 10 network along with the G0/1 interface of the router. R1 is also connected to the Internet through a service provider through its G2/0 interface. From a security perspective (and a NAT perspective), the G0/1 interface connects to the “trusted” or “inside” network (from the company’s perspective), and the G2/0 interface connects to the “untrusted” or “outside” network. Now the router itself does not have a problem with IP connectivity to the Internet because the router has a globally reachable IP address (34.0.0.3) in this example. The users are ...

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