What is VPN??

What is VPN

The 
Virtual Private Network - VPN - has attracted the attention of many 
organizations looking to both expand their networking capabilities and 
reduce their costs.

The 
VPN can be found in workplaces and homes, where they allow employees to 
safely log into company networks. Telecommuters and those who travel 
often find a VPN a more convenient way to stay connected to the 
corporate internet. No matter your current involvement with VPNs, this 
is a good technology to know something about. This VPN tutorial 
involves many interesting aspects of network protocol design, Internet 
security, network service outsourcing, and technology standards. 

What Exactly Is A VPN?


A VPN supplies network connectivity over a possibly long physical 
distance. In this respect, a VPN is a form of WAN The key feature of a 
VPN, however, is its ability to use public networks like the Internet 
rather than rely on private leased lines. VPN technologies implement 
restricted-access networks that utilize the same cabling and routers as 
a public network, and they do so without sacrificing features or basic 
security.


VPN supports at least three different modes of use:

Remote access client connections LAN-to-LAN internetworking Controlled access within an intranet

VPN Pros and Cons


Like many commercialized network technologies, a significant amount of 
sales and marketing hype surrounds VPN. In reality, VPNs provide just a 
few specific potential advantages over more traditional forms of 
wide-area networking. These advantages can be significant, but they do 
not come for free.

The 
potential problems with the VPN outnumber the advantages and are 
generally more difficult to understand. The disadvantages do not 
necessarily outweigh the advantages, however. From security and 
performance concerns, to coping with a wide range of sometimes 
incompatible vendor products, the decision of whether or not to use a 
VPN cannot be made without significant planning and preparation. 

Technology Behind VPNs

Several network protocols have become popular as a result of VPN developments:

PPTP L2TP IPsec SOCKS

These protocols emphasize authentication and encryption in VPNs. 
Authentication allows VPN clients and servers to correctly establish 
the identity of people on the network. Encryption allows potentially 
sensitive data to be hidden from the general public.

Many 
vendors have developed VPN hardware and/or software products. 
Unfortunately, immature VPN standards mean that some of these products 
remain incompatible with each other.

VPN Solutions and Key Features

A 
VPN supplies network connectivity over a possibly long physical 
distance. In this respect, a VPN is a form of WAN VPNs enable file 
sharing, video conferencing and similar network services. Virtual 
private networks generally don't provide any new functionality that 
isn't already offered through alternative mechanisms, but a VPN 
implements those services more efficiently / cheaply in most cases.

A 
key feature of a VPN is its ability to work over both private networks 
as well as public networks like the Internet. Using a method called tunneling, a VPN use the same hardware infrastructure as existing Internet or internet links. VPN technologies includes various security mechanisms to protect the virtual, private connections. 
Specifically, a VPN supports at least three different modes of use:

Internet remote access client connections LAN-to-LAN internetworking Controlled access within an intranet

Internet VPNs for Remote Access


In recent years, many organizations have increased the mobility of 
their workers by allowing more employees to telecommute. Employees also 
continue to travel and face a growing need to stay connected to their 
company networks.

A VPN 
can be set up to support remote, protected access to the corporate home 
offices over the Internet. An Internet VPN solution uses a client/server design works as follows:

1. A remote host (client) wanting to log into the company network firstconnects to any public ISP.


2. Next, the host initiates a VPN connection to the company VPN server. This connection is made via a VPN clientinstalled on the remote host.


3. Once the connection has been established, the remote client can 
communicate with the internal company systems over the Internet just as 
if it were a local host. Before VPNs, remote workers accessed company 
networks over private leased lines or through dialup remote access 
servers. While VPN clients and servers careful require installation of 
hardware and software, an Internet VPN is a superior solution in many 
situations. VPNs for Internetworking

Besides 
using virtual private networks for remote access, a VPN can also bridge 
two networks together. In this mode of operation, an entire remote 
network (rather than just a single remote client) can join to a 
different company network to form an extended intranet. This solution 
uses a VPN server to VPN server connection. Intranet / Local Network VPNs

Internal 
networks may also utilize VPN technology to implement controlled access 
to individual subnets within a private network. In this mode of 
operation, VPN clients connect to a VPN server that acts as the network 
gateway.

This type of VPN 
use does not involve an Internet Service Provider (ISP) or public 
network cabling. However, it allows the security benefits of VPN to be 
deployed inside an organization. This approach has become especially 
popular as a way for businesses to protect their WIFI local networks.