Virtual private network technology runs on the idea of tunnelling. It establishes and maintains a logical network connection. The data from the system is converted and compiled into packets using a certain VPN protocol format. These packets are then encapsulated within some carrier protocol or base which is then transmitted flanked by VPN client and server. In the internet based virtual private networks the protocols are encapsulates within IP packets only. VPN undergoes protocol based formatting of data into packets to support authentication and encryption of the tunnels to secure them from any virtual threat.
VPN services are based upon the principle of tunneling. There are two types of tunneling, like voluntary and compulsory tunneling. Under the task of tunneling the VPN protocol builds and maintains a logical network connection of the systems using the network at any given point in time. VPN front end processor or we can call it point of presence server represent the logic built in broker device used under the compulsory tunneling process to authenticate and associate the client with the VPN servers. Under compulsory tunneling the details of VPN server connectivity would be hidden from its clients. This way the whole management control is easily transferred to the ISP over the tunnels. In order to attain the total management control the service providers have to install and maintain FEP devices also, which increases their work load for sure. There are a few types of VPN protocols like:
- PPTP – It stands for point to point tunneling protocol. The major OS and Smartphone can use PPTP with the help of their inbuilt software only. They don’t need to download any further software for that sake.
- IPSec – it stands for internet protocol security. A protocol suite used in combination with L2TP tunneling. It requires licensing cost to be paid by the user to access its services. It exists at the network layer that is layer number three of the OSI model. It acts as an encryption scheme within PPTP or L2TP.
- SSTP – The latest protocol it is available on windows vista and windows 7 computer systems only.
- OpenVPN – it is a free and open source software application that implements VPN solutions. It is considered to be very secure, and, like SSTP uses SSL to transport traffic, making it usable in almost any network environment. OpenVPN is compatible with all OSs (unlike SSTP that only work on Windows 7 and Vista), but has the downside that the OpenVPN software has to be installed on the client device
The L2TP is actually a combination of L2F and PPT protocols for VPN tunneling.L2F was initially created by Cisco. But later on it was combined with the very popular PPTP to create a better resolution for VPN tunneling. Both PPTP and L2TP exist at the layer two, or data link layer of the OSI model.