The value of tmnxNatFwdActionOutPort specifies the outside port.
If the value of tmnxNatFwdActionType is not equal to 'create', do not
set the value of tmnxNatFwdActionOutPort.
If any port is acceptable, do not specify
the value of tmnxNatFwdActionOutPort; in this case, the system will
use the same value as for the inside port.