Reference Manual for the ProSafe VPN Firewall FVS318v3
Firewall Protection and Content Filtering 4-5
January 2005

Inbound Rules (Port Forwarding)

Because the FVS318v3 uses Network Address T ranslation (NAT), your network presents only one
IP address to the Internet, and outside users cannot directly address 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 firewall to direct inboun d
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 FVS318v3 VPN Firewall. Only
enable 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 inbou nd Web
(HTTP) requests from any outside IP address to the IP address of your Web server at any time of
day. This rule is shown in Figure 4-3:
Figure 4-3: Rule example: a local public Web server
Note: Some residential broadband ISP accounts do not allow you to run any server
processes (such as a Web or FTP server) from your location. Your ISP may periodically
check for servers and may suspend your account if it discovers any active services at
your location. If you are unsure, refer to the Acceptable Use Policy of your ISP.