What are the three main VPN protocols?

There are three main protocols used by VPN-providers to ensure you an anonymous and secured connection : PPTP, L2TP and OpenVPN. These protocols have two main goals: they must transmit data in a secured way. That’s why they can use other protocols having a precised objective.

1- PPTP (Point-to-point tunneling protocol):

The maximum encryption PPTP can provide is 128bit. IP protocol deals with the transfer of data. Transfer-protocol TCP allows an authentication between the VPN client and the server during the connection.

Advantages:

easy, simple and quick to use
no need to install a software
recognized by the most of software and operators

Disadvantages:

less secured than the two other protocols
more often blocked by ISP (Internet Service Providers)

2- L2TP/IPSec:

L2TP provides a 128bit AES maximum encryption. UDP protocol to establishes a tunnel but it does not provide an authentication system. IPSec secures the tunnel between the VPN server and the client; thus IPSec encrypted data and L2TP set up the link. The two go hand in hand.

Advantages:

more secured than PPTP
no need to install a software

Disadvantages:

less recognized by softwares and operators
less quick than PPTP

3- OpenVPN:

OpenVPN is overall a free software. It uses TLS/SSL security protocol and includes also two steps: authentication and data encryption.

OpenVPN makes a double authentication: from the client to the VPN server and vice-versa, which means a reinforced security. This authentication is based on an asymmetric encryption using a key of 2048bit or 4096bit.

Once the authentication is made, OpenVPN uses symmetric encryption to encrypt data. This encryption uses also a key of a variable length: 128bit, 256bit, 448bit. The longer the key is, the more secured connection it provides.

Avantages: