Netopia 430 S/T, Reference Manual

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4-2 Netopia ISDN Router Reference Guide
Key Features of IP Network Address Translation
(NAT)
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NAT is selectable on a per connection basis, optionally allowing
real addresses to be used for intranet connections and proxied
addresses to be used for Internet connections.
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The NAT user can use any combination of proxied and
unproxied addresses simultaneously on the two B-channels. For
instance, one unproxied address connection profile can be
used to connect to a central office, while another proxied
address connection profile can simultaneously connect the
user’s Netopia ISDN Router and LAN to the Internet.
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The single proxy address is acquired at connection time from
the answering side. The address can be assigned by the
remote router from either a dynamic pool of addresses or a
fixed, static address.
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Security is made simpler and more reliable by only having to
firewall one IP address and by obscuring the internal network
structure from the Internet.
Using NAT
Follow these steps to use NAT.
1. Pick a network number for your local (internal) network. This
can be any IP address range you want. For this example, we will
use 10.0.0.0.
Note: The outside world (the external network) will not see this
network number.
2. Using the internal network number, assign addresses to the
local nodes on your LAN. For example, you may assign
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10.0.0.1 to your Netopia ISDN Router
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10.0.0.2 to a node running as a World Wide Web ser ver
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10.0.0.3 to an FTP ser ver
■ 10.0.0.4 to a Macintosh computer