User`s guide

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Using the Advanced Router Functions
Using the Virtual Server
Generally, a router protects your internal network computers by
filtering out unrecognized packets from the Internet. Therefore, all
network computers behind your Wireless Router are invisible to
the Internet—the Internet sees only your Wireless Router.
If you are hosting your own Web site on a Web server that resides
on your internal network, you can set up your Wireless Router to
act as a Virtual Server and direct all incoming traffic to your
internal Web server.
In general, all Internet servers use fixed TCP/UDP service port
numbers. (For instance, WWW is TCP/80, FTP is TCP/21, and so
on.) Therefore, any packets downloaded from the WAN which
have destination port numbers that match your Wireless Router’s
virtual server ports are forwarded to the pre-defined network IP.
The destination port number can be kept the same or mapped into
another network port. TCP ports are always mapped to TCP ports.
For example, if you have an FTP server (port21) at 192.168.8.5, a
mail server (port110) at 192.168.8.6, and a VPN server at
192.168.8.7, then you need to specify the virtual server as shown
below:
FTP port 21 = 192.168.8.5 port 21
POP3 port 110 = 192.168.8.6 port 110
VPN port 1723 = 192.168.8.7 port 1723