The word ‘Technology’ has it’s origins from Greek. Technology is a result of science and engineering. It is the manner adopted by humans to improve their surroundings.One of the method involved is – making use of tools and machines to carry out tasks efficiently. With time we have observed rapid growth and change in technology like PCS, podcasts, teleconferencing, videoconferencing, electronic teaching centers, etc. One amongst the several technologies is the Virtual Private Network.A VPN is a private network that uses a public network like the internet to connect remote sites and users. A VPN uses “virtual” connections routed through the internet from the company’s private network to the remote site or employee.A public network like the internet can help carry VPN traffic based on certain standard protocols. A Service Level Agreement (SLA) between the VPN customer and the VPN service provider is drawn in order to enable the existence of a service providers private network.Advantages of a VPN:* Improved security and productivity* Simplified network topology* Reduced operational and transportation costs* Faster Return on Investment* Extensive connectivity across the globeFeatures:* Reliable* Secure* Scalable* Network and policy managementTypes of VPN:1. Remote Access VPN2. Intranet VPN3. Extranet VPN1. Remote Access VPN:Remote access VPN is a user-to-LAN (Local Area Network) connection used by an organization whose employees need to connect to the private network from remote locations.The remote access VPN helps save on costs over toll free expenditure and is secure (encrypted tunnels across a public network like the internet), scalable2. Intranet VPN (Interconnecting corporate sites):The intranet VPN helps in cost saving over dedicated, leased lines. There exist tunneled connections and encryption that enables reliable throughput.3. Extranet VPN (connecting corporate site(s) to external business partners or suppliers)Extranet VPN extends WAN (Wide Area Network) to business partners.VPN Security:The most important part of a VPN solution is security. A VPN helps putting private data on public networks and this raises concerns about threats to that data and the impact of data loss. A Virtual Private Network must provide security services in area of Authentication.Authentication ensures that a user or system is who the user claims to be. Security is thus ensured.Authentication Mechanisms:* login name, password, PIN (password – specified number of digits followed by 8 bits that constantly changes at regular intervals)* a computer readable token like a smart card* fingerprint, retinal or iris patternTunneling:Tunneling is a very important part of a VPN. Tunneling involves placing a packet within another packet and sending it over a network. The network (like the internet) over which the packet is sent and the *tunnel interface understand the protocol of the outer packet.Protocols used in Tunneling:* Carrier protocol – The protocol used by the network that the information is traveling over* Encapsulating protocol – The protocol (GRE, *IPSec, L2F, PPTP, L2TP) that is wrapped around the original data* Passenger protocol – The original data (IPX, NetBeui, IP) being carriedExample: A packet that uses a protocol not supported on the internet like NetBeui can be placed inside an IP packet and can be sent safely over the internet.Considering the current business scenario/trend that involves increased commuting/telecommuting and widely spread global operations, with employees who need to connect to central resources from remote sites in order to communicate with each other, technologies like the VPN prove to be very handy and vital.*Tunnel Interface: The two points where the packet enters and exits the network.*IPsec is the security portion of the IP standard that is supported by the Client. IPsec performs packet-by-packet authentication and end-to-end encryption. In addition, IPsec supports the IP within IP encapsulation for network address translation.