About Network Address Translation (NAT)?

Posted by Rudi on Stack Overflow See other posts from Stack Overflow or by Rudi
Published on 2010-05-23T04:55:10Z Indexed on 2010/05/23 5:00 UTC
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Just curious about a particular scenario of NAT. Let's suppose we have 4 computers sharing a global IP address under the NAT. I understand that the NAT box keeps an internal record to know which computer to forward requests to. But let's say on computer #2 I'm trying to download a file. And let's say on computer #1, #3, and #4, I'm just browsing the web normally. When the browser initiates a TCP connection to get that file, how does it know which computer to give it to? I mean like, each of the four computers is using port 80 to browse the web right? How does the NAT's record distinguish which "port 80" belongs to which computer?

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