USRobotics U.S. Robotics SureConnect ADSL Ethernet/USB Router User Manual

Page 173

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U.S. Robotics SureConnect ADSL Ethernet/USB Router User Guide

Network Address Translation (NAT) hides internal IP addresses of a network from the outside
world and provides access to the Internet for multiple machines using a single or fixed number of
public IP addresses. The NAT framework supports both dynamic and static NAT. The nat
command enables dynamic NAT processing

With the nat command, all private addresses are mapped to the IP address of the specified WAN
interface.


nat -o [-interface <interface>] [-alias_address <addr>] [-unregistered_only yes|no] [-same_ports
yes|no] [-disable] [-status]


- interface <interface>
Configures the specified WAN interface to use dynamic Network Address Translation. For all
packets transmitted from the WAN interface, the source address is modified to use IP address of
the WAN interface. The source port of the packet may be modified, as required. Packets received
on the WAN interface will have their destination address modified appropriately to reach the
appropriate machine on the LAN network.

-alias_address <ip_address>
The source address field of the outbound packets from the WAN interface will be overwritten with
the specified ip_address.

-unregistered_only [yes | no]
If yes, only the outbound packets with unregistered source IP addresses are translated. All the
outbound packets with the registered source IP addresses are forwarded on the WAN interface
without translation. This is useful if you have one more subnet having registered IP addresses that
share the common WAN link with the subnet having unregistered IP addresses.

Registered addresses are addresses reachable and advertised in the Internet, whereas
unregistered addresses are private addresses which are not reachable through the Internet.
Currently there is no command to display registered addresses.

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