ICR-1601
92
Virtual Server & NAT Loopback
"Virtual Server" allows you to access servers
with the global IP address or FQDN of the
gateway as if they are servers existed in the
Internet. But in fact, these servers are located in
the Intranet and are physically behind the
gateway. The gateway serves the service
requests by port forwarding the requests to the
LAN servers and transfers the replies from LAN
servers to the requester on the WAN side. As
shown in example, an E-mail virtual server is
defined to be located at a server with IP address
10.0.75.101 in the Intranet of Network-A,
including SMTP service port 25 and POP3 service
port 110. So, the remote user can access the E-
mail server with the gateway’s global IP
118.18.81.33 from its WAN side. But the real E-
mail server is located at LAN side and the
gateway is the port forwarder for E-mail service.
NAT Loopback allows you to access the WAN global IP address from your inside NAT local network. It
is useful when you run a server inside your network. For example, if you set a mail server at LAN side, your
local devices can access this mail server through gateway’s global IP address when enable NAT loopback
feature. On either side are you in accessing the email server, at the LAN side or at the WAN side, you don’t
need to change the IP address of the mail server.
Virtual Computer
"Virtual Computer" allows you to assign LAN
hosts to global IP addresses, so that they can be
visible to outside world. While so, they are also
protected by the gateway firewall as being
client hosts in the Intranet. For example, if you
set a FTP file server at LAN side with local IP
address 10.0.75.102 and global IP address
118.18.82.44, a remote user can access the file
server while it is hidden behind the NAT
gateway. That is because the gateway takes
care of all accessing to the IP address
118.18.82.44, including to forward the access
requests to the file server and to send the
replies from the server to outside world.