To make a local web server public:
1. Assign your web server either a fixed IP address or a dynamic IP address using DHCP address reservation.
In this example, your router always gives your web server an IP address of 192.168.1.33.
2. On the Port Forwarding / Port Triggering page, configure the modem router to forward the HTTP service to the
local address of your web server at 192.168.1.33.
HTTP (port 80) is the standard protocol for web servers.
3. (Optional) Register a host name with a Dynamic DNS service, and specify that name on the Dynamic DNS page
of the modem router.
Dynamic DNS makes it much easier to access a server from the Internet because you can enter the name in
the web browser. Otherwise, you must know the IP address that the ISP assigned, which typically changes.
How the Modem Router Implements the Port Forwarding
The following sequence shows the effects of a port forwarding rule:
1. When you enter the URL www.example.com in your browser, the browser sends a web page request message
with the following destination information:
•Destination address. The IP address of www.example.com, which is the address of your modem router.
•Destination port number. 80, which is the standard port number for a web server process.
2. The modem router receives the message and finds your port forwarding rule for incoming port 80 traffic.
3. The router changes the destination IP address in the message to 192.168.1.123 and sends the message to that
4. Your web server at IP address 192.168.1.123 receives the request and sends a reply message to your router.
5. Your modem router performs Network Address Translation (NAT) on the source IP address and sends the reply
through the Internet to the computer or WiFi device that sent the web page request.
Manage Port Triggering for Services and Applications
Port triggering is a dynamic extension of port forwarding that is useful in these cases:
•An application must use port forwarding to more than one local computer (but not simultaneously).
•An application must open incoming ports that are different from the outgoing port.
With port triggering, the modem router monitors traffic to the Internet from an outbound “trigger” port that you specify.
For outbound traffic from that port, the modem router saves the IP address of the computer that sent the traffic. The
Manage Port Forwarding and Port Triggering
Nighthawk X4S AC2600 WiFi VDSL/ADSL Modem Router Model D7800