Filter
Top Products
62
5.4 Virtual Ports
A port number represents a "channel" or entryway for network communications. Port numbers allow different
computers to utilize network resources without interfering with each other. Port numbers most commonly appear
in network programming, particularly socket programming. Sometimes, though, port numbers are made visible to
the casual user. For example, some websites on the Internet use a URL like the following:
http://www.sitename.com:8100/
In this example, the number 8100 refers to the port number used by the browser to connect to the web server.
The standard port number used by web sites is 80, so this number does not need to be included with the URL
(although it can be). In IP networking, port numbers can theoretically range from 0 to 65535. Most popular network
applications, though, use port numbers at the lower end of the range (such as 80 for HTTP). Ports are similar to
doors and windows of your house, with port 80 acting as the front door. If these are not open you could not enter
the house. This is the same case with ports on a network. If the ports for a specific IP address are not open then
you could not gain access to that IP address.
Note: The term port also refers to several other aspects of network technology. A port can refer to
Ethernet connection points, such as those on a hub, switch, or router. The term port is also used to refer
to a physical connection point for peripheral devices such as serial, parallel, and USB ports.
Another analogy would be: if a WAN IP address is similar to the phone number identify a site, IP ports are similar
to telephone extensions, in that they allow communication with specific devices within a site that all share the
same external (WAN) IP address. A router is a device which allows multiple computers and other IP enabled
equipment to share that single WAN IP address. It functions like a “switchboard operator” – opening ports creates
an association between those port numbers and the LAN IP address of specific equipment on the LAN behind the
router. When the router sees a ‘call’ for a specific ‘extension’ (port), it directs that data stream to the (LAN IP
address of the) equipment associated with that ‘extension’ (port).
5.5 Pre-Installation
Before beginning the installation, please answer the following questions:
Do you have Hi-speed Internet? ______________
There are many types of high speed Internet available. The most common ones are T1, Cable, and DSL
(in order of speed). The DVR is not compatible with a dial-up connection.
Note: EverFocus suggests having a minimum upload speed of 256KBps. This can be addressed
by your Internet Service Provider.
What type of modem/router do you have? ______________
Modem/router model name/ #
The modem/router was either installed by your Internet service provider or purchased by you to establish
a connection to the Internet. A router assigns different internal IP addresses to local computers; this
allows multiple computers to access the Internet through the same external IP address.