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3G Broadband Wireless Router MBR624GU User Manual
3-6 Protecting Your Network
v1.0, January 2009
Inbound Rules (Port Forwarding)
Because the router uses Network Address Translation (NAT), your network presents only one IP
address to the Internet, and outside users cannot directly access any of your local computers.
However, by defining an inbound rule you can make a local server (for example, a Web server or
game server) visible and available to the Internet. The rule tells the router to direct inbound traffic
for a particular service to one local server based on the destination port number. This is also known
as port forwarding.
Remember that allowing inbound services opens holes in your firewall. Enable only those ports
that are necessary for your network. Following are two application examples of inbound rules.
Inbound Rule Example: A Local Public Web Server
If you host a public Web server on your local network, you can define a rule to allow inbound Web
(HTTP) requests from outside IP addresses to the IP address of your Web server at any time of day.
This rule is shown in the following figure:
The settings are:
• Service. From this list, select the application or service to be allowed or blocked. The list
already displays many common services, but you are not limited to these choices. Use the
Services screen to add any additional services or applications that do not already appear.
Note: Some broadband ISP accounts do not allow you to run any server processes (such
as a Web or FTP server) from your location. Your ISP might periodically check for
servers and might suspend your account if it discovers any active services at your
location. If you are unsure, see the acceptable use policy of your ISP.
Figure 3-4