Figure B-3. Single Ip Address Operation Using Nat - NETGEAR DG814 DSL Reference Manual

Reference Manual for the Model DG814 DSL Modem Internet Gateway
The router accomplishes this address sharing by translating the internal LAN IP addresses to a
single address that is globally unique on the Internet. The internal LAN IP addresses can be either
private addresses or registered addresses. For more information about IP address translation, refer
to RFC 1631, The IP Network Address Translator (NAT).
The following figure illustrates a single IP address operation.
192.168.0.2
192.168.0.3
192.168.0.4
192.168.0.5
Figure B-3. Single IP Address Operation Using NAT
This scheme offers the additional benefit of simple firewall-like protection because the internal
LAN addresses are not available to the Internet through the translated connection. All incoming
inquiries are filtered out by the router. This filtering can prevent intruders from probing your
system. However, using port forwarding, you can allow one PC (for example, a Web server) on
your local network to be accessible to outside users.
B-8
Private IP addresses
assigned by user
192.168.0.1 172.21.15.105
IP addresses
assigned by ISP
Internet
7786EA
Networks and Routing Basics