NETGEAR WGR826V manual Single IP Address Operation Using NAT

Reference Manual for the 54 Mbps Wireless Router with Phone Adapter WGR826V

Single IP Address Operation Using NAT

In the past, if multiple computers on a LAN needed to access the Internet simultaneously, you had to obtain a range of IP addresses from the ISP. This type of Internet account is more costly than a single-address account typically used by a single user with a modem, rather than a router. The WGR826V Wireless Router employs an address-sharing method called Network Address Translation (NAT). This method allows several networked computers to share an Internet account using only a single IP address, which may be statically or dynamically assigned by your ISP.

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

Private IP addresses assigned by user

IP addresses assigned by ISP

192.168.0.1172.21.15.105

Internet

192.168.0.4

192.168.0.5

Figure B-3: Single IP Address Operation Using NAT

This scheme offers the additional benefit of 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 computer (for example, a Web server) on your local network to be accessible to outside users.

B-8 Network, Routing, and Firewall Basics

202-10051-01, March 2005