The term, virtual private network (VPN), is defined most fundamentally as an extension of a private network over a public one like the Internet. VPNs let users receive and transmit data over shared networks as if the devices they’re using were connected to the private network directly. As a result, this can attribute the benefits of private network management, security, and functionality to any applications that run over the VPN.
Lots of companies use VPNs to let their employees access their corporate intranets securely even when they’re not at the office, and no one without the VPN software is able to get into the network, which protects the company’s virtual infrastructure. Companies often do this if they have multiple offices that occupy physically separate locations (i.e. companies whose office buildings may be in different cities, states, or countries) because they can connect the systems of all these buildings using a VPN, and these brings cohesion to their virtual network.
Individual users on the Internet often attempt to encrypt wireless transactions via VPN, too, because this would let them get around the censorship and geo-restrictions for certain content. They may also be attempting to connect to proxy servers so that they can protect their location and personal identity from external entities. Some Internet sites refuse to give access to any user that employs VPN technology that the sites recognize because they only want to deal with users whose IP addresses can be logged, and VPN users typically are not supplying real IP addresses. The sites that screen for this kind of anonymity do so because they want to prevent that kind of circumvention of restrictions.
Virtual tunneling protocols, dedicated connections, and/or traffic encryption are used to establish virtual, point-to-point connections, which is how a VPN is created. A VPN that is accessible from the public Internet is able to give users some of the benefits typically sought from wide area networks (WANs). As far as any user would be concerned, it is not only possible but uncomplicated to remotely access the available resources in a private network.
Point-to-point topology is the conventional way to construct a VPN, and VPNs rarely ever extend to connect or support broadcast domains, which means that common services like Microsoft Windows NetBIOS, for example, might not work as well as they would on a local area network (LAN). However, there are designers who have engineered methods to fix that with layer-2 tunneling protocols and VPN variants like Virtual Private LAN Service (VPLS).
Types of VPNs
VPNs are either classified as site-to-site or remote-access. Site-to-site VPNs are used to connect two networks whereas remote-access VPNs are used to connect a computer to a network. For most companies that rely on VPNs, remote-access VPNs are their optimal choice because they need employee devices to be able to access their company intranet remotely if they’re on a business trip, for example, or simply working from home. On the other hand, some use site-to-site VPNs so that their employees in separate offices that have their own intranets can connect from one to the other seamlessly. Some companies employ both, layering them.