Contemporary Controls EIGR Series Application Manual page 10

Application #6 – Port Forwarding to Access a Private Web Server
The firewall will normally block all WAN-side requests. Port
forwarding allows computers on the WAN side to access
devices on the LAN side by opening up selected WAN IP
ports. The only WAN-side requests that will be forwarded
through the IP router are those that specify both the router's
WAN address and a destination IP port number that exists in
the router's IP port forwarding table. When this match is
made, the message is forwarded to the indicated IP address
on the LAN side.
This is very useful when only one public IP address is
available, but there is a need to access multiple LAN-
192.168.92.101
192.168.92.102
Enhance Security with a Whitelist
Specify which WAN-side devices
can use port forwarding.
Internal IP Address LAN IP Port
192.168.92.101/24
192.168.92.101:80
Application Guide – EIGR Series
side devices. In this example, we want to access a private
web server at 192.168.92.101 which is normally invisible from
the Internet. Using port forwarding, we allow a WAN-side
request made to the router's public (WAN) address. For
additional security, the port numbers have been translated.
You can also select Port Range Forwarding to allow an entire
range of addresses through the firewall. Note that any
WAN-side device can use port forwarding — but you can
greatly enhance security by creating a whitelist of allowed
WAN-side devices. This is illustrated at the bottom of the
page.
WAN IP Port
80 8080
STATUS PWR
RESET
H
WAN
L
1
2
LAN
3
4
192.168.92.1
10
External IP Address
1.2.3.4
WAN Request
1.2.3.4:8080
AG-EIGR0000-AA0