Using a Virtual Private Network or VPN, a private network can extend across a public network, such as the Internet, in a secure way. We often use a VPN in an organization to access the remote network. Many of us might have heard the terms PPTP, L2TP, OpenVPN, SSTP, IKEv2 VPN. What are they actually, and how are they different from each other? Let’s understand that in more detail.

PPTP VPN

PPTP VPN was developed by a consortium founded by Microsoft, Ascend Communications, 3Com, and others. It uses the Point-to-Point Tunnelling Protocol or PPTP for implementing a VPN. PPTP uses a control channel over TCP and a GRE or Generic Routing Encapsulation (What is GRE protocol and how does it work?) tunnel to encapsulate PPP (What is PPP protocol and how does it work?) packets.

As per this protocol, the end-user first initializes a TCP connection using TCP port 1723. The TCP connection is then used to initiate and manage a second GRE tunnel to the same peer. In a PPTP GRE packet, the acknowledgment field replaces the typical routing field, and the modified GRE packet is then encapsulated into IP packets that allow tunneling within PPP.

The PPTP specification does not describe encryption and authentication. Instead, it relies on the Point-to-Point Protocol being tunneled to implement security functionality.

Pros :

• PPTP VPN is easy to set up.
• It is fast.

Cons :

• Serious security vulnerabilities have been found in this protocol.

L2TP VPN

L2TP VPN uses the Layer 2 Tunneling Protocol to implement a VPN. In this protocol, the entire L2TP packet, including the L2TP header and payload, is sent within a UDP. Once an L2TP tunnel is established, higher-level protocols run through the tunnel. The network traffic between peers is bidirectional. It is possible to set up multiple virtual networks across a single tunnel.

L2TP VPN does not provide any encryption and confidentiality by itself, rather it relies on the encryption protocol that passes within the tunnel to provide security. IPSec Protocol (What is IPSec Protocol and how does it work?) is often used to secure the L2TP packets by providing confidentiality, …