VPN software enables private communications over public computer networks and telecommunications infrastructure. Virtual private networks (VPN) provide network connectivity over long distances, and support network services such as file sharing and video conferencing. In this sense, a VPN is a type of a wide area network (WAN). VPN software uses a technique called tunneling to establish and maintain a logical network connection. Via this VPN connection, packets are structured according to a particular VPN protocol and then encapsulated within another carrier or base protocol (typically Internet Protocol or IP). After their transmission between the VPN client and the VPN server, the packets are de-encapsulated.

VPN connections require both VPN client software and VPN server software. Although virtual private networks don’t provide new functionality, they provide network services more efficiently and less expensively than other methods, such as a local area network (LAN).

Applications

VPN applications include Internet remote access client connections, LAN-to-LAN internetworking, and controlled access within an intranet. Businesses and other organizations that use VPN technology can support employees who work from home or from remote offices. Both client-side and server-side VPN software includes various security mechanisms for protecting virtual, private connections.

Benefits of VPN software include the ability to work over both private networks and public networks, and features such as mobile VPN. VPN software may support both voluntary and compulsory tunneling. With voluntary tunneling, the VPN client connects to a carrier network provider. In the case of an Internet VPN, the carrier is an Internet service provider (ISP). Using the voluntary connection, the VPN client creates a tunnel to the VPN server. With compulsory tunneling, on the other hand, the carrier network manages the creation of the VPN connection. After the VPN client establishes a regular connection, the carrier brokers a special VPN connection between the VPN client and the VPN server. In this way, compulsory VPN tunneling software authenticates clients before associating them with VPN servers. Most VPN software supports VPN tunneling protocols such as point-to-point tunneling protocol (PPTP), layer-two tunneling protocol (L2TP), layer-three tunneling protocol (L3TP), and Internet protocol security (IPsec). Types of VPN software include trusted delivery networks or trustedVPNs, secure VPNs, mobile VPNs, layer 2 VPNs, layer 3 VPNs, and virtual private LAN service (VPLS). VPN software that supports virtual router routing instances and VPN routing and forwarding (VRF) is also available.