- [FreeLAN](http://www.freelan.org/)
- [GVPE](http://software.schmorp.de/pkg/gvpe.html)
- [l2tpd](http://sourceforge.net/projects/l2tpd)
+- [n2n](http://www.ntop.org/products/n2n/)
- [Nest](http://www.targeted.org/nest/)
- [OpenS/WAN](https://www.openswan.org/projects/openswan/)
- [OpenVPN](http://openvpn.net/)