Edimax Technology i-Watcher Pan/Tilt Internet IP Camera - Manual (Page 30)

A word about terminology
The term gateway is used generically to define a device that connects a local network to the
Internet. A gateway may be a router, a PC running software which allows it to act as a
gateway such as a proxy server, or some other device. Most home networks use a NAT
(Network Address Translation) router as a gateway. The term gateway router refers to such
a device.
Static versus Dynamic IP address
The IP address (or addresses) your ISP has (have) provided you will either be static, which
means it never changes, or dynamic, meaning it can change periodically. Dynamic
addresses present an additional challenge when trying to locate your network from the
Internet since your address may have changed since the last time you checked it. How
often your dynamic address changes varies from one service provider to another. Also, any
time you reboot your cable or DSL modem, you are likely to get a new address when
reconnecting. The solution to the ever-changing IP address is known as DDNS or dynamic
domain name service. A DDNS will allow you to find your network by a domain name, such
as mynetcam.no-ip.com, rather than needing to know the IP address.
13-2. Network Address Translation (NAT)
Most home routers and business firewalls today perform something called NAT or Network
Address Translation. NAT translates your external or WAN IP address into an internal
address inside your gateway router. What this means is, you can think of your router as
being divided into two halves, the LAN side (inside) and the WAN side (outside or Internet
side). When a connection request arrives at your router from the Internet, it will not get any
farther than the WAN side unless you have specifically instructed your router to pass this
type of request to a specific device on your LAN. This process is known as port forwarding
or port redirecting.
13-3. Port Forwarding
All TCP/IP (Internet) networking uses software ports. Ports can be thought of as channels
on your television. By default, all web page traffic is on channel (port) 80. By default, the
IP-Cam uses port 80 to deliver its web page to your browser and port 1600 to send video.
Therefore, both of these channels (ports) must be open (not blocked by your router/firewall)
to incoming traffic in order for you to connect to the camera from the Internet. Also, these
two ports must be forwarded or redirected to the camera’s LAN IP address by your gateway
router. Your router’s setup software should provide a utility for port forwarding or redirecting.
Router configuration contains setup help for some popular home networking gateway
routers currently on the market.
Note:
Forwarding ports to your camera does not pose any additional security risk to your LAN.
Before setting up port forwarding, it is best to configure your camera to use a static LAN IP
since your port forwarding setup will need to be updated if the camera’s LAN IP address
changes.
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