Setting up a virtual private network (VPN)

Local area networks (LAN ) networks are internal to an organization, i.e. the connections between machines belong to the organization. These networks are increasingly connected to the Internet through equipment interconnection. It happens often that companies feel the need to communicate with subsidiaries, customers or even staff geographically remote from the Internet or remote that individuals want to create a secure VLAN.

However, the data transmitted on the Internet are much more vulnerable than when running on an internal network because the path is not defined in advance, which means that the data network infrastructure using public-owned operators . Thus it is not impossible that on the path, the network may be listened to by a user indiscreet or misappropriated. It is not conceivable to transmit in such conditions of sensitive information.

The first solution to address this need for secure communication is to connect remote networks with dedicated lines. However, most companies can not afford to connect two remote LAN through a dedicated line, it is sometimes necessary to use the Internet as a medium of transmission.

A good compromise is to use the Internet as a transmission medium using a protocol of "encapsulation" (tunneling) ie encapsulating data way to transmit encrypted. This is called virtual private network (VPN or RPV noted, an acronym for Virtual Private Network) to denote the artificially created.
This virtual network is said because it connects two "physical" (LAN) by a bond unreliable (Internet), and private computers only because of local side of the VPN can "see" the data.

The VPN system allows for a secure connection at a lower cost, if this is the implementation of terminal equipment. In return it does not ensure a quality of service comparable to a leased line as the physical network is public and therefore not guaranteed.