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3.9.3 Virtual Server & Virtual Computer
Virtual server is another name for port forwarding used by some routers. In computer networking,
port forwarding or port mapping is an application of network address translation (NAT) that redirects a
communication request from one address and port number combination to another while the packets
are traversing a network gateway, such as a router or firewall. This technique is most commonly used to
make services on a host residing on a protected or masqueraded (internal) network available to hosts
on the opposite side of the gateway (external network), by remapping the destination IP address and
port number of the communication to an internal host.
Port forwarding allows remote computers (a computers on the Internet) to connect to a specific
computer or service within a private local‐area network (LAN). So you can deploy some servers in your
Intranet with the firewall protection by your gateway. This device's NAT firewall filters out unrecognized
packets to protect your Intranet, so all hosts behind this device gateway are invisible to the outside
world. If you wish, you can make some of them accessible by enabling the Virtual Server Mapping.
However, a virtual computer is a host in the Intranet whose IP address is global and is visible to the
outside world. Since it is in the Intranet, it is protected by the firewall gateway when it acts like a node
in the Internet.
In "Virtual Server & Virtual Computer" page, there are two list windows for all virtual servers and
virtual computer. "Virtual Server List" window lists the public port used in the Internet, server IP at LAN
side, private port used in the Intranet, used protocol for the service on the server and the integrated
time schedule rule for all virtual servers. There is an "Add" button for you to add and create new virtual
server, and the "Edit" button to modify the existed virtual server settings. On "Virtual Computer List"
window, the mapping of the global IP address and the local IP address for all virtual computers are
listed. There is also a "Add" button for you to add and create new virtual computer, and the "Edit"
button to modify the existed virtual computer.
Index skipping is used to reserve slots for new function insertion, when required.
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