Open source VPNs

There are two good open source projects for the VPNs. One is OpenSwan, and IPSec based. And the second is OpenVPN an SSL based.

Basically OpenSwan uses the IPSec functionality in the Kernel, and user space tools and front end. But the OpenVPN is based into userspace functionality, so interoperability is question when compared to OpenSwan.

OpenSwan project:

http://www.openswan.org/

OpenVPN project:

http://openvpn.net/index.php/home.html

Both the projects comparision and configuration information you can get from this Debian Administration website article

http://www.debian-administration.org/articles/563

-srinivas.