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Network Address TranslationΒΆ
Network Address Translation, or NAT, involves changing properties of a packet as it passes through a router. Typically this is done to mask or alter the source or destination to manipulate how such packets are processed by other hosts.
The most common examples are:
Source NAT, also known as Outbound NAT, which translates the source address and port of a packet to mask its origin.
Destination NAT, commonly referred to as Static NAT or Port Forwards which translate the destination address and port of a packet to redirect the packet to a different target host behind the router.
TNSR applies NAT based on the configured mode and the presence of directives
that set inside
(internal/local) and outside
(external/remote)
interfaces.
An inside
interface is a local interface where traffic enters and it will
have its source hidden by NAT. An outside
interface is an interface where
that translation will occur as a packet exits TNSR. An example of this is shown
in Outbound NAT.
Note
NAT is processed after ACL rules. For more information, see ACL and NAT Interaction.
Note
NAT-specific virtual reassembly parameters have been deprecated in favor of shallow virtual reassembly. See IP Reassembly.