# Specifying Inside and Outside Interfaces

You must mark interfaces that participate in NAT translation as residing on the inside or the outside network.

| Caution: Only packets routed between an inside and an outside interface are subject to translation.

You can unmark an interface by using the no version of this command.

ip nat

- Use to mark an IP interface as participating in NAT translation.
- Use the keyword (inside or outside) to specify the side of the network on which the interface resides.
- Example
  host (config-if) # ip nat inside
- Use the no version to unmark the interface (the default) so that it does not participate in NAT translation.
- See ip nat.