Understanding NAT

Dear Experts,

Is there any article or can anyone explain to me as simple as possible on how NAT works in a firewall / router?

I know NAT is to access a different IP subnet from the source, but I just can’t seem to understand on the way it works and how it is to be configured.
Anonymous KHIT EngineerAsked:
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yo_beeDirector of Information TechnologyCommented:
NAT stands for Network Address Translation.
Simplest explanation is a Public IP to translate to a private IP.
This helps you shape where certain IP addresses are assigned.  It comes in handy when you have a few or more public addresses.
Here is an example:
You have an email server that has a private address of, but there is no way to reach this server from the outside world so you need a public address  The public address has to know where to go when it hits your firewall.  That is where NAT comes in.
You put a rule in for to translate to   That is no the entire story.  You also need a ACL rule to state what port or ports are allowed to this address.

This is a much better explanation

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jorge diazSECommented:
You can also look into this resource, it's simple to read and to the point.

Sandeep GuptaConsultantCommented:
please go through:


they have explained very nicely and you can learn every bits and pieces of security, firewall, nat, networking etc..
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