Billion Electric Company 7800 User Guide

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Virtual Server allows you to direct incoming traffic from WAN side (identified by Protocol and 

External port) to the Internal server with private IP address on the LAN side. The Internal port is 

required only if the external port needs to be converted to a different port number used by the 

server on the LAN side.

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.

Examples of well-known and registered port numbers are shown below, for further information, 

please see IANA’s website at: 

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

Real Audio