Billion 7800DX, User Manual, Page: 185 / 270

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One-to-One NAT
One-to-One NAT maps a specific private/local address to a global/public IP address. If user has
multiple global/public IP addresses from your ISP, you are free to use one-to-one NAT to assign
some specific public IP for an internal IP like a public web server mapped with a global/public IP for
outside access.
Valid:
Check whether to valid the one-to-one NAT mapping rule.
WAN Interface:
Select one based WAN interface to configure the one-to-one NAT.
Global IP address:
The Global IP mapped to an internal device. It can be left empty, and under this
circumstance, it can be reached through the WAN IP of interface set in the field above.
Internal Address:
The IP address of an internal device in the LAN.
For example,
you have an ADSL connection of pppoe_0_8_35/ppp0.1 interface with three fixed
global IP, and you then can assign the other two global IPs to two internal devices respectively.
If you have a WEB server (IP address: 192.168.1.3) and a FTP server (IP address: 192.168.1.4) in
local network, owning a public IP address range of 123.1.1.2 to 123.1.1.4 assigned by ISP. 123.1.1.2
is used as WAN IP address of the router, 123.1.1.3 is used for WEB server and 123.1.1.4 is used for
FTP server. With One-to-One NAT, the servers with private IP addresses can be accessed at the
corresponding valid public IP addresses.