Virtual Private Network (VPN)

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VPN is a private network that uses a public
network (usually the Internet) to connect
remote sites or users together.
A VPN (Virtual Private Network) is a way of
creating a secure connection to and from a
network or computer.
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You connect to the Internet through your ISP.
The VPN client software on your computer
initiates a connection with the VPN server.
The VPN server encrypts the data on the
connection so it cannot be read by others
while it is in transit.
The VPN server decrypts the data and passes
it on to other servers and resources.
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Under this application only a single VPN
gateway is involved. The other party involved
in negotiating the secure communication
channel with the VPN Gateway is a PC
or laptops that is connected to the Internet
and running VPN Client software.
The VPN Client allows telecommuters and
traveling users to communicate on the central
network and access servers from many
different locations.
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Significant cost savings by reducing the
burden of long distance charges associated
with dial-up access. Also helps increase
productivity and peace of mind by ensuring
secure network access regardless of where an
employee physically is.
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A simple method for VPN is PPTP. It is a
software based VPN system that uses your
existing Internet connection.
By using your existing Internet connection, a
secure "tunnel" is created between two points
allowing a remote user to connect to a
remote network.
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Two or more networks are connected using a
dedicated line from an ISP.
These are usually T1's, Metro Ethernet, or OC
lines.
The main strength of using a leased line is that is
a circuit-based point-to-point connection.
It does not go out over the public Internet, so
there performance is not degraded by routing
problems, latency, and external congestion.
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Site-to-site is the same much the same thing
as point-to-point except there is no
"dedicated" line in use. Each site has it's own
internet connection which may not be from
the same ISP or even the same type.
With Intranet VPN, gateways at various physical
locations within the same business negotiate a
secure communication channel across the
Internet known as a VPN tunnel.
An example would be a network that exists in
several buildings connected to a data center or
mainframe that has secure access through
private lines. Users from the networks on either
side of the tunnel can communicate with one
another as if it were a single network. These may
need strong encryption and strict performance
and bandwidth requirements.
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Almost identical to Intranets, except they are
meant for external business partners.
As such, firewall access restrictions are used
in conjunction with VPN tunnels, so that
business partners are only able to gain secure
access to specific data / resources, while not
gaining access to private corporate
information.
1. Cost Savings with a VPN
A VPN can save an organization money in
several situations:
A) Eliminating the need for expensive longdistance leased lines
B) Reducing long-distance telephone charges
C) Offloading support costs
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Organizations historically needed to rent
network capacity such as T1 lines to achieve
full, secured connectivity between their office
locations.
With a VPN, you use public network
infrastructure including the Internet to make
these connections and tap into that virtual
network through much cheaper local leased
lines or even just broadband connections to a
nearby Internet Service Provider (ISP)
A VPN also can replace remote access servers
and long-distance dialup network
connections commonly used in the past by
business travelers needing to access to their
company intranet.
For example, with an Internet VPN, clients need
only connect to the nearest service provider's
access point that is usually local.
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With VPNs, the cost of maintaining servers
tends to be less than other approaches
because organizations can outsource the
needed support from professional thirdparty service providers.
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To use a VPN, each client must possess the
appropriate networking software or hardware
support on their local network and
computers.
When set up properly, VPN solutions are easy
to use and sometimes can be made to work
automatically as part of network sign on.
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VPN technology also works well with WiFi
local area networking.
Some organizations use VPNs to secure
wireless connections to their local access
points when working inside the office.
These solutions provide strong protection
without affecting performance excessively.
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VPNs require detailed understanding of
network security issues and careful
installation / configuration to ensure
sufficient protection on a public network like
the Internet.
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The reliability and performance of an
Internet-based VPN is not under an
organization's direct control. Instead, the
solution relies on an ISP and their quality of
service.
VPN products and solutions from different
vendors have not always been compatible due
to issues with VPN technology standards.
Attempting to mix and match equipment may
cause technical problems, and using
equipment from one provider may not give as
great a cost savings.
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http://www.howstuffworks.com/vpn.htm
http://www.skullbox.net/vpn.php
http://compnetworking.about.com/od/vpn/f
/vpn_benefits.htm
http://www.alpha-apr.com/vpn/
http://www.alpha-apr.com/vpn/
http://www.vpninfo.com/how_vpn_works.htm

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