Wikipedia
University of Tsukuba Virtual Private Network, UT-VPN is a free and open source software application that implements 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 uses SSL/TLS security for encryption and is capable of traversing network address translators (NATs) and firewalls. It was written by Daiyuu Nobori and SoftEther Corporation, and is published under the GNU General Public License (GPL) by University of Tsukuba.
UT-VPN has compatible as PacketiX VPN product of SoftEther Corporation. UT-VPN developed based on PacketiX VPN, but some functions was deleted. For example, the RADIUS client is supported by PacketiX VPN Server, but it is not supported by UT-VPN Server.