6 Most Common VPN Protocols 1) Open VPN. OpenVPN is a highly secure and very popular protocol commonly used by many VPN providers. ... 2) Secure Socket Tunneling Protocol (SSTP) ... 3) Internet Key Exchange Version 2 (IKEv2) ... 4) Wire Guard. ... 5) Point-to-Point Tunneling Protocol (PPTP) ... 6) Layer 2 Tunneling Protocol (L2TP)