User Manual

VisionNet 202ER ADSL Ethernet Router User’s Guid
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 Specify both a destination address (or range) and a
destination port (or range) if you want this translation rule to
apply to accesses to the specified server type at the
specified IP address or network.
7. Follow steps 7-12 under "The napt rule" on page 63 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 VisionNet 202ER
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.
Bimap rules can be used to provide external access to a LAN
device. They do not provide the same level of security as rdr rules,
because rdr rules also reroute incoming packets based on the port
ID. Bimap rules do not account for the port number, and therefore
allow external access regardless of the destination port type
specified in the incoming packet.
Figure 30 shows the fields used to establish a bimap rule.
Figure 30. NAT Rule – Add Page (bimap Flavor)
Follow these instructions to add a bimap rule (see steps 1-4 under
"The napt rule" on page 63 for specific instructions corresponding to
steps 1 and 2 below):
1. Display the NAT Rule – Add Page, select BIMAP as the
Rule Flavor, and enter a Rule ID.
2. Select the interface on which this rule will be effective.
3. In the Local Address field, type the private IP address of the
computer to which you are granting external access.