The Bimap Rule: Performing Two-Way Translations - SMC Networks Barricade SMC7401BRA User Manual

If you enter only the network ID portion of the destination
address, then the rule will apply to outbound traffic to all
computers on network.
7. In the [Destination Port From:] field, type a port ID number
if you want the rule to apply only to outbound traffic to servers
of this type.
8. You can specify a range using the From/To fields if you want
the rule to apply to a range of port types, or enter the same
port number in both fields. See step 6 for creating an RDR
Rule on page 73 for an explanation of port IDs.
9. Follow steps 8-12 under The NAPT Rule on page 70
to submit your changes.

The Bimap rule: Performing two-way translations

Unlike the other NAT flavors, the Bimap flavor performs address
translations in both the outgoing and incoming directions.
In the incoming direction, when the specified ADSL Barricade
interface receives a packet with your public IP address as the
destination address, this address is translated to the private IP
address of a computer on your LAN. To the external computer, it
appears as if the access is being made to the public IP address,
when, in fact, it is communicating with a LAN computer.
In the outgoing direction, the private source IP address in a data
packet is translated to the LAN's public IP address. To the rest of
the Internet, it appears as if the data packet originated from the
public IP address.
Adding NAT Rules
81