There are many VPN products available on the market, both commercial and open source. Almost all of these VPN products can be separated into the following four categories:
Some people argue that OpenVPN is also an SSL-based VPN, as it uses an SSL or TLS-like protocol to establish a secure connection. However, we have created a separate category for OpenVPN, as it is different from almost every other SSL-based VPN solution.
We will now go into more detail about each of the four types of VPNs:
One of the oldest VPN protocols is the Point-to-Point Tunneling Protocol (PPTP) developed by Microsoft and Ascend in 1999. It is officially registered as RFC2637 (see https://www.ietf.org/rfc/rfc2637.txt ...