A full-featured SSL/TLS based VPN solution.

OpenVPN is a full-featured open source SSL/TLS VPN solution that accommodates a wide range of configurations and authentication models. Starting with the fundamental premise that complexity is the enemy of security, OpenVPN offers a cost-effective, lightweight alternative to other VPN technologies that is well-adapted for small companies and
organizations.

The OpenVPN security model is based on SSL/TLS, the industry standard for secure communications over the internet. OpenVPN implements OSI layer 2 or 3 secure network extension using the SSL/TLS protocol, supports flexible client authentication methods based on certificates, smart cards, and/or 2-factor authentication.

Due to the continuous research of higher performance, OpenVPN is being extended with kernel acceleration on a number of platforms. The idea is to keep the fast path (the data channel) in kernelspace and thus eliminate any overhead brought by the userspace processing. This solution is called DCO: Data Channel Offload.