Overview; Nat Configuration - Netopia R2020 User Reference Manual

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The Netopia R2020 uses Internet Protocol (IP) to communicate both locally and with remote networks. This
chapter shows you how to configure the Router to route IP traffic. You also learn how to configure the Router to
serve IP addresses to hosts on your local network.
Netopia's SmartIP features IP address serving and Network Address Translation. This chapter describes how to
use the Network Address Translation feature of SmartIP and Multiple Network Address Translation (MultiNAT).
Note: When you configured your Netopia R2020 using SmartStart, Network Address Translation was enabled by
default. You have the option of disabling it, if you wish. This is done through the System Configuration screens
using Console-based Management.
This section covers the following topics:
"Overview" on page 10-1
"NAT configuration" on page 10-4
"Binding Map Lists and Server Lists" on page 10-18
"NAT Associations" on page 10-22
"MultiNAT Configuration Example" on page 10-24
"IP subnets" on page 10-29
"Static routes" on page 10-31
"IP address serving" on page 10-35
O O O O v v v v e e e e r r r r v v v v i i i i e e e e w w w w
NAT (Network Address Translation) is a means whereby one or more IP addresses and/or IP service ports are
re-mapped into other values. This aliasing serves two functions:
It allows the addresses of many computers to be represented by only one or a few addresses, saving you
money.
It can be used as a security feature by obscuring the true addresses of important machines from potential
hackers on the Internet.
To help you understand some of the concepts discussed here, it may be helpful to introduce some NAT
terminology.
The terms mapping or remapping refer to rules that translate one or more addresses on the Netopia Router's
LAN to another address or addresses on the other side of the Netopia Router's WAN link (typically the Internet).
The terms private and internal refer to addresses on the Netopia Router's LAN network that are protected or
obscured from the NAT remappings. These NATed addresses cannot be seen from the Internet side of the
Netopia Router's WAN connection.
Multiple Network Address Translation and IP Setup 10-1