Netgear DG814 DSL User Manual download pdf (Page 98)

Reference Manual for the Model DG814 DSL Modem Internet Gateway

B-8 Networks and Routing Basics

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.

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.

7786EA

92.168.0.2

92.168.0.3

92.168.0.4

92.168.0.5

192.168.0.1 172.21.15.105

Private IP addresses

assigned by user

Internet

IP addresses

assigned by ISP

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Netgear DG814 DSL User Manual Page 98