Behind the NAT box — one public address, two devices, and a table that tells the replies apart
Your laptop said 192.168-something. Here is the machinery that makes that legal — a rewrite on the way out, a rewrite on the way back, and a five-column table that remembers who was talking to whom.
Inside the site — private, unroutable, invisible
laptop192.168.0.10
phone192.168.0.23
NAT router
200.24.5.8
one real address
The Internet
web server25.8.3.2 : 80
It never sees a private address. Ever.
The packet on the wire
The NAT translation table
Private address
Private port
External address
External port
Protocol
bitsarebits.com · CSE 316 — Data Communication & Networking · DHCP and NAT