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A Visual Review of NAT and PAT
Many people are confused by Cisco’s NAT/PAT naming conventions, such as “inside local”, etc. so I have put together a few diagrams that might help. Since we can’t actually see the packets as they traverse the media, by "looking" we mean what we would “see” if we were to install protocol analyzers locally and globally and examine the addresses within the packets’ IP headers. Since I can’t draw a protocol analyzer, in the diagrams I’ll use an "X-ray eyeball" that’s able to see the packet headers.