BEC 5200 Series User Manual page 39

Virtual Server
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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