What is VPN?
A VPN (Virtual Private Network) is a network technology that makes a secure network connection over a public network such as the Internet or a private network of a service provider. Generally, government agencies, educational institutions, and large corporations use VPN technology to enable the remote users to connect securely to the private network.
A VPN can connect multiple sites over a long distance like a WAN (Wide Area Network). VPN are often used to extend the intranet to a wide user base. In the same way, education institution use VPN to connect between campuses across the country or the world.
User has to use a unique identification and password to gain access to the private network. A PIN (Personal Identification Number) is used as authentication token. A PIN is changed according to specific frequency, usually every 30 seconds.
PVN Protocols
There are many ways to secure the transport of data traffic over the public network.
1) IPSec (IP Security) is used to secure communication over the Internet. It can use as either tunneling or transport mode to encrypt data traffic in a VPN. Tunneling will encrypt the entire data while transport mode will encrypt only the message within the data packet. IPSec is referred as “security overlay” because it is used as a security layer for other protocols.
2) SSL (Secure Sockets Layer) and TLS (Transport Layer Security) use cryptography to secure communication over the Internet. Both SSL and TLS use handshake method of authentication that involves negotiation between client and server. Certificate is use as cryptography key that is store on both client and server.
3) PPTP (Point to Point Tunneling Protocol) is tunneling protocol that used to connect the remote client to a private server over the Internet. PPTP is widely used because of its easy configuration and maintenance and it comes with Windows operating system.
4) L2TP (Layer 2 Tunneling Protocol) is a protocol that is used to tunnel data traffic between two sites over the Internet. L2TP is often used one after another with IPSec (as a security layer) to transfer L2TP data packet securely. A VPN that implements L2TP/IPSec has to use a shared key or the certificates.
VPN technology use sophisticated encryption to ensure security and privacy and prevent interception of data between the private sites. A VPN needs a network administrator to continually monitor the overall architecture and scope of VPN to ensure secure data communication and privacy.
Advantages and Disadvantages of VPN
VPN is less expensive than leased private line in building a private network. It is relatively easy, fast and flexible, and it is ideal choice for corporation.
However, VPN lacks QoS (Quality of Service) over the Internet; it means it can cause packet loss and other performance issues. VPN also have vendor interoperability issue that one vendor may not compatible with another vendor. Because of disadvantages prevent widespread acceptance and deployment of VPN technology.