User's Manual

Advanced Configuration /
Virtual Server
67
BEC 6800RUL User Manual
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 designated as “well-known ports”.
The registered ports are numbered from 1024 through 49151. The remaining ports, referred to as
dynamic ports, or private ports, are numbered from 49152 through 65535.
Examples of well-known and registered port numbers are shown below, for further information,
please see IANA’s website at:
http://www.iana.org/assignments/port-numbers
Well-known and Registered Ports
Port Number
Protocol
Description
20
TCP
FTP Data
21
TCP
FTP Control
22
TCP & UDP
SSH Remote Login Protocol
23
TCP
Telnet
25
TCP
SMTP (Simple Mail Transfer Protocol)
53
TCP & UDP
DNS (Domain Name Server)
69
UDP
TFTP (Trivial File Transfer Protocol)
80
TCP
World Wide Web HTTP
110
TCP
POP3 (Post Office Protocol Version 3)
119
TCP
NEWS (Network News Transfer Protocol)
123
UDP
NTP (Network Time Protocol)
161
TCP
SNMP
443
TCP & UDP
HTTPS
1503
TCP
T.120
1720
TCP
H.323
4000
TCP
ICQ
7070
UDP
RealAudio