OpenVPN 2.3.6

An open source application that implements VPN (virtual private network) techniques to employ secure point to point connections for routed and bridged network configurations, OpenVPN uses a custom security protocol that uses SSL/TLS for key exchange. It is capable of allow data to travel through NATs (network address translators) and firewalls of many types. 

Known to be a very secure VPN application, OpenVPN is the solution you need for protecting your connection from the source to the destination. The software allows peers to authenticate using a pre shared key, username and password, and certificates. It uses OpenSSL encryption as well as the SSLv3/TLSv1 protocol while also containing many different types of features to properly accommodate your network configuration. 

The software offers quite a few internal security features and has up to 256-bit encryption through OpenSSL. The application runs on a custom security protocol based on SSL and TLS while also offering support for smart cards using PKCS#11 based cryptographic token. OpenVPN can be extended using third party plugins and scripts which can all be called at user defined entry points.

OpenVPN is a multiplatform application that is not only available for Windows, but also Mac OS X and quite a few Linux distributions. There is limited support for mobile based applications, and currently only offers support for Windows Mobile 6.5 and below, so it isn't very viable for mobile based security, however it is impressive at the amount of support there is for desktop computing. 

Considering how often nowadays VPN software can come into great use, OpenVPN uses many advanced techniques to giving you the most out of the security you need for your connections. Many pieces of software include OpenVPN as their VPN of choice to provide the best possible VPN connection for maximum security, making the software a more well-known name.

It is important to note that OpenVPN isn't exactly very novice friendly. I would say without sufficient knowledge of VPN based software that there might be better choices out there if you do not really know what you are doing. However, OpenVPN's techniques at security are one of a kind and definitely worth trying out if you are a veteran of computer networking based applications.