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Chapter 4 - Firewall Software
If instead of mapping a static IP address from your ISP, you employed Multi-Tech’s Global Dynamic
WAN port addressing method, you can assign a predefined Global Dynamic WAN port address to the
Firewall’s WAN port and then map your servers to that WAN port address the same way you map a
static IP address from your ISP.
The Virtual Server Setup dialog box defines how the servers are connected to the one global IP
address. The static IP address (of the Router) in our virtual server connection example above is
added to the Global IP Addresses group in the Virtual Server Setup dialog box.
With static IP addressing, the Global IP Address is the IP address that is seen by the Internet. This
global address will be used by the Firewall’s virtual server feature to filter by functionality the activity
of the traffic to and from the Internet. The addresses that we assigned to our servers in the virtual
server example are unregistered addresses that are only seen by the Firewall. These local IP
addresses are arbitrarily assigned to servers in our virtual server connection example.
These local addresses are then individually mapped (one at a time) to the global address by
protocol(s) and function (or Port). The Web server, assigned the unregistered IP address of
192.168.0.20, can be mapped to the Global Address (in this case, the Router’s static IP Address of
204.20.12.10) with its protocol information (TCP and UDP) and Port WWW-HTTP(80). The FTP
server, with the unregistered IP address 192.168.11.30 is mapped with both TCP and UDP protocols
and the port information FTP(21,20). Finally (to complete our example), the Mail server with the
unregistered IP address of 192.168.0.40 is mapped with both TCP and UDP protocols and both
POP-3(110) and SMTP(25) for its Port information.