ControlByWeb WEBRelay-10+ User Manual page 25

WebRelay-10 Plus™ Users Manual
Port Forwarding
The router can be configured to allow outside access to the ControlByWeb devices. All requests from the
Internet to any device on the local network must use the public IP address (203.0.113.254). With only a
single IP address, TCP ports are used to identify the intended device for the incoming message.
Using the mailing address analogy, the port is similar to a post office box. The IP address specifies the
location, and the port specifies the specific recipient. Port numbers can be set to any number between 1
and 65535. However, many port numbers are reserved for specific applications and should be avoided.
As a general rule, numbers above 8000 are safe to use. All of the ControlByWeb™ devices come from
the factory with the HTTP port set to 80, which is the standard port for HTTP. In the example above, the
WebRelay-10 Plus™ HTTP port will be changed to port 8000 and WebRelay™ port will be changed to
8001. Once the ports are changed in the two ControlByWeb™ devices, the router must be set up for port
forwarding.
Port forwarding associates the IP address of each local device with an assigned port. In the above
example, the address 192.168.1.25 for the WebRelay-10 Plus™ would be associated with port 8000. The
address 192.168.1.26 for WebRelay™ would be associated with port 8001. The WebRelay-10 Plus™
would be accessed from the Internet by entering the public IP address of the router, plus the port number
assigned to the WebRelay-10 Plus™ in the URL window of the browser, http://203.0.113.254:8000. All
Internet requests to the router for port 8000 would be forwarded to the WebRelay-10 Plus™. Similarly, all
request for port 8001 would be forwarded to WebRelay.
Note: When an HTTP request comes in to the router without the specific port specified
(http://203.0.113.254), the router will handle this as a port 80 request (default HTTP port). In other words,
http:// 203.0.113.254 is exactly the same as http://203.0.113.254:80.
Router configuration can vary widely. Some routers have the capability of translating the addresses and
the ports, which would require no port configuration change on the ControlByWeb device. For example,
the router would be configured so that messages sent to http://203.0.113.254:8000 would be forwarded to
http://203.0.113.254:80, which is the default HTTP port.
An example screenshot of a router configuration is given below. This setup allows the two
ControlByWeb™ devices in the above example to be accessed remotely from the Internet.
Figure Appendix C.3 - Port Range Forwarding Note: Routers will vary, this is an example.
Xytronix Research & Design, Inc. Page 25