NAT was created for one reason only: because there weren't enough IPv4 addresses to go around. Port mapping and connection tracking firewalls were invented in

NAT was created for one reason only: because there weren't enough IPv4 addresses to go around. Port mapping and connection tracking firewalls were invented in 1989,[1][2] while network translation was created in 1994. [3][4] The private address space was only reserved in 1996.[5] The Firewalls book was published in 1994 (which meant that it was being written in the 1992-3 timeframe).[6] People were protecting networks before NAT. [1] https://en.wikipedia.org/wiki/Firewall_(computing)#Connection_tracking https://en.wikipedia.org/wiki/Firewall_(computing)#Connectio... [2] https://en.wikipedia.org/wiki/Circuit-level_gateway https://en.wikipedia.org/wiki/Circuit-level_gateway [3] https://www.rfc-editor.org/rfc/rfc1631 https://www.rfc-editor.org/rfc/rfc1631 [4] https://en.wikipedia.org/wiki/Cisco_PIX https://en.wikipedia.org/wiki/Cisco_PIX [5] https://www.rfc-editor.org/rfc/rfc1918 https://www.rfc-editor.org/rfc/rfc1918 [6] https://en.wikipedia.org/wiki/Firewalls_and_Internet_Security https://en.wikipedia.org/wiki/Firewalls_and_Internet_Securit...