Openswan - Definition from the Hotspot Shield Glossary
Openswan is used on Linux devices and is an implantation of IPsec. Openswan has operated as the main VPN software for the Linux OS since its inception in 2005 and has been included in many of the Linux distributions including Red Hat, Ubuntu, Gento and Fedora.
Openswan has support for many of IPsec’s extensions including IKEv2, NAT Traversal and Digital Certificates. This software can be fully downloaded and the core code can be modified, it also is extremely flexible and has a large developer community working on its continual improvement. In 2012 Libreswan forked from Openswan due to disputes over ownership.