The working of VPN is not a tough deal to understand, though it is. But, before that, you need to get an idea about the protocols or set of rules in laymen terms, used by VPN in providing a secure personal network. Let’s tell you more about it:

SSL (Secured Socket Layer): It uses a 3-way handshake method for assuring proper authentication between the client and server machines. The authentication process is based on cryptography where certificates behaving as cryptographic keys already stored in the client and server, are used for initiating the connection.

IPSec (IP Security): This protocol can work on transport mode or tunnelling mode, so that it can do its job of securing the VPN connection. The difference between the two is, transport mode only encrypts the Payload in the data i.e. only the message present in the data, whereas tunnelling mode encrypts the whole data to be transmitted.

PPTP (Point-To-Point Transfer Protocol): It connects a user located at some remote location to a private server in a VPN network, and also uses the tunnelling mode for its operations. Its low maintenance and simple working makes it the most widely adopted VPN protocol, further credit goes to the inbuilt support provided by Microsoft Windows.

L2TP (Layer Two Tunnelling Protocol): It facilitates the tunnelling of data between two geographical sites over the VPN network, often used in combination with the IPSec protocol which further aids to the security layer of the communication.

So, you have a rough idea about the various protocols used in a VPN. We shall proceed further and see how it works. When you are connected to a public network such as internet, you can assume that all your data is flowing through a big tunnel along with the data of other users.

So, anyone who wants to spy on you, can easily sniff your data packets from the network. When VPN comes into the scene, it actually provides you a personal tunnel inside that big tunnel. And all your data is transformed into garbage values, so no one can recognize it.

Authentication: In this phase, data packets are first encapsulated, basically wrapped inside another packet and some headers and other stuff are attached, all done to conceal the identity of the data packets. Now, your device initiates the connection by sending a Hello request to the VPN server, which replies with an acknowledgement and asks for the user credentials to clarify the authenticity of the user.

Tunnelling: After the authentication phase is finished, what we say, an imaginary tunnel is created which provides a direct point to point connection through the internet. We can send whatever data we want to via that tunnel.

Encryption: After we’ve successfully created the tunnel, we can send whatever information we want to, but that information is still not safe if we are connected to a free VPN service, which is also used by other people. So, we encrypt the data packets before sending them over the tunnel, thus barring any other user to peep into our packets, as he will only see some unrecognizable rubbish data flowing through the tunnel.

Say, you want to access a website, your device will send the access request to the VPN server which will then forward the request to the website in its name and receive the data from it. This data will then be transferred back to your device. And the website will think, the VPN server is the user and will find no trace of your device as the actual user.

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