Network Address Translation/Port Address Translation
Cisco Security Appliances can statically or dynamically translate internal private (RFC 1918)
addresses or any other address used internally to the assigned public addresses. They can also
hide multiple hosts on the internal network behind a single public address. A one-for-one
translation of addresses from internal to external, or from external to internal, is referred to
as Network Address Translation (NAT). If multiple internal addresses are translated behind
a single external address, each outgoing connection uses a different source port. This is called
Port Address Translation (PAT).