PAT and NAT

Red Squirrel

No Lifer
May 24, 2003
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I've read on both. I know what NAT is and use it at home, well most other people do as well. But what makes PAT different? From what I read it just seems like its the same, exept PAT involves making port forwarding to different ports. So connecting to port 80 on the router outside may lead to an internal server on port 10000. But isin't this still a NAT? Just with port forwarding enabled? Or am I just missing something?
 

BornStar

Diamond Member
Oct 30, 2001
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I'm sure my answer will get torn to shreds but what most people refer to as NAT is in actuality PAT. PAT will assign multiple inside IPs to one outside IP whereas NAT usually requires one outside IP for each inside IP.
 

spidey07

No Lifer
Aug 4, 2000
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NAT = network address translation. It works at layer3 regardless of layer4 (TCP/UDP port numbers)

PAT = port adress translation. It works at layer4

All SOHO gear uses PAT unless specifically told to do different.

So to your question - anytime source/destination addresses are changed by a device...that is technically port address translation. Network Address Translation only changes the******/dst layer3 IP addresses and doesn't change anything else.

It's mainly semantics however.
 

cross6

Senior member
Jun 16, 2005
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Yeah it's kind of misleading that people call soho routers "NAT routers", when it's really PAT they are using.