The Rdr Rule: Allowing External Access To A Lan Computer - ZyXEL Communications Prestige 623 series User Manual

Prestige 623 Series Dual-link ADSL Router
To specify that data from all LAN addresses should be translated, type 0 (zero) in each From
field and 255 in each To field.
If you use non-sequential private addresses, you can create an additional napt rule for each
separate range of addresses.
These addresses should correspond to private addresses already in use on your network (either
assigned statically to your computers, or assigned dynamically using DHCP, as discussed in
chapter on DHCP).
Step 7. When you have completed entering all information, click Submit. A page displays to confirm
the change.
Step 8. Click Close to return to the NAT Configuration page. The new rule should display in the NAT
Rule table.
Step 9.
On the NAT Configuration page, ensure that the Enable radio button is turned on and click
Submit. A page displays to confirm your changes. Refer to the section on Committing Your
Changes and Rebooting the Prestige to save your changes to permanent memory and make your
changes take effect.

8.6.2 The RDR Rule: Allowing External Access to a LAN Computer

You can create an rdr rule to make a computer on your LAN, such as a Web or FTP server, available to
Internet users without requiring you to obtain a public IP address for that computer. The computer's private
IP address is translated to your public IP address in all incoming and outgoing data packets.
Without an rdr rule (or bimap rule described on page 8-16), the Prestige blocks
attempts by external computers to access your LAN computers.
The following example illustrates using the rdr rule to provide external access to your web server:
Your Prestige receives a packet from the Internet containing a request for access to your
Web server. The packet header contains your public IP address (which is assigned to the
Prestige's WAN port) as the destination IP address, and 80 as the destination port number.
Port 80 is commonly used for web servers. Because you have set up an rdr rule for
incoming packets with destination port 80, the Prestige recognizes the data as a request
for Web server access. The Prestige changes the destination IP address in the packet to
the private IP address assigned to your Web server and forwards the data packet to it.
Your Web server sends data packets in response. Before the Prestige forwards these
packets to the Internet, it changes the source IP address in the data packets from the Web
server's private address to your LAN's public address. To an external Internet user, then, it
appears as if your Web server uses your public IP address.
Follow these instructions to add an rdr rule:
8-10 Configuring Network Address Translation