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5.3.6 Virtual Server
In TCP 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 need to configure your router to forward these incoming
connection attempts using specific ports to the PC on your network running the application.
You also need to use port forwarding if you wish to host an online game server.
The reason is that when using NAT, your publicly accessible IP address is used by and
points to your router, which needs to deliver all traffic to the private IP addresses used by
your PCs. Please see the
WAN
configuration section of this manual for information on NAT.
The Internet Assigned Numbers Authority (IANA) is the central coordinator for the
assignment of unique parameter values for Internet protocols. Port numbers range from 0 to
65535, but only port numbers 0 to 1023 are reserved for privileged services and are
