It lets OpenSSL do all the encryption and authentication work, allowing OpenVPN to use all the ciphers available in the OpenSSL package. OpenVPN uses the OpenSSL library to provide encryption of both the data and control channels.

Additionally, commercial licenses are available. It was written by James Yonan and is free software, released under the terms of the GNU General Public License version 2 (GPLv2). SoftEther VPN, a multi-protocol VPN server, also has an implementation of OpenVPN protocol. For example, DD-WRT has the OpenVPN server function. OpenVPN has been ported and embedded to several systems. It is capable of traversing network address translators (NATs) and firewalls. It uses a custom security protocol that utilizes SSL/TLS for key exchange. It uses the OpenSSL encryption library extensively, as well as the TLS protocol, and contains many security and control features.

When used in a multiclient-server configuration, it allows the server to release an authentication certificate for every client, using signatures and certificate authority. OpenVPN allows peers to authenticate each other using pre-shared secret keys, certificates or username/ password. It implements both client and server applications. OpenVPN is a virtual private network (VPN) system that implements techniques to create secure point-to-point or site-to-site connections in routed or bridged configurations and remote access facilities.

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