FreeLAN

FreeLAN is computer software that implements peer-to-peer, full mesh, virtual private network (VPN) techniques for creating secure point-to-point or site-to-site connections in routed or bridged configurations and remote access facilities. It is free and open-source software licensed under the GNU General Public License Version 3 (GNU GPLv3).

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

Authentication
FreeLAN has several ways to authenticate peers with each other. From version 2.0 FreeLAN offers pre-shared keys, certificate-based, and username-password based authentication.