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At a minimum, IP routing
and appropriate IP addresses must be configured on the router. To
enable dynamic local IP address translation, perform the following
steps:
-
Define a standard IP access-list for the inside network by using the
access-list access-list-number {permit | deny}
local-ip-address command.
Define an IP NAT pool for the inside network by using the
ip nat pool pool-name start-ip end-ip {netmask
netmask | prefix-length prefix-length} [type rotary]
command, which is explained in Table
.
Map the access-list to the IP NAT pool by using the
ip nat inside source list access-list-number pool
name command.
Enable NAT on at least one inside and one outside interface with the ip nat {inside | outside}
command.
Only packets moving between inside and outside interfaces
are translated. For example, if a packet is received on an inside interface but is not destined for an outside interface, it will not be translated.
Example
shows a sample dynamic NAT configuration.
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Lab
Activity |
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Our
small company has recently been assigned the
network number 206.222.222.0 by ARIN.
Previously the company was using a private IP
address on the internal network. Now that the
company is going to be connected to the
Internet, we need to either go to each and
every workstation and configure it with a new
IP address, or to use some kind of IP address
translation at the router. For security
reasons our company does not want the
computers to be directly on the Internet,
using real IP addresses. Since our company has
a large number of computers it would be too
time consuming to enter all of the static
address translations into the router. Our
alternative is dynamic network address
translation. It is our job to configure the
ISDN connection and implement the address
translation. |
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