Billion Electric Company BiPAC 7402G - Manual (Page 120)

802.11g ADSL2+ VPN Firewall Router
Chapter 4: Configuration
Virtual Server (“Port Forwarding”)
In TCP/IP and UDP networks a port is a 16-bit number used to identify which application program
(usually a server) incoming connections should be delivered to. Some ports have numbers that are pre-
assigned to them by the IANA (the Internet Assigned Numbers Authority), and these are referred to as
“well-known ports”. Servers follow the well-known port assignments so clients can locate them.
If you wish to run a server on your network that can be accessed from the WAN (i.e. from other
machines on the Internet that are outside your local network), or any application that can accept
incoming connections (e.g. Peer-to-peer/P2P software such as instant messaging applications and P2P
file-sharing applications) and are using NAT (Network Address Translation), then you will usually need to
configure your router to forward these incoming connection attempts using specific ports to the PC on
your network running the application. You will also need to use port forwarding if you want to host an
online game server.
The reason for this is that when using NAT, your publicly accessible IP address will be used by and point
to your router, which then needs to deliver all traffic to the private IP addresses used by your PCs.
Please see the WAN configuration section of this manual for more information on NAT.
The device can be configured as a virtual server so that remote users accessing services such as Web
or FTP services via the public (WAN) IP address can be automatically redirected to local servers in the
LAN network. Depending on the requested service (TCP/UDP port number), the device redirects the
external service request to the appropriate server within the LAN network
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