The most commonly used NAT function is to allow all of the internal LAN devices
to be privately addressed using one of the three nonroutable address ranges and have
all outbound traffic passed through the firewall and re-assigned a single public
address,usually that of the firewall’s WAN interface.This is the same mechanism that
all residential “routers”use to allow homeowners to run many computers off one
DSL or cable connection.
NOTE
When broadband Internet service was first introduced to the residential
market, users could only get a single IP address and connect a single
computer to those circuits. In fact, you usually had to ...
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