Openswan is a free implementation of IPsec (Internet Protocol Security) and the IKE (Internet Key Exchange), which usually requires strong cryptography in order to provide cryptography and authentication services, that results in the formation of VPN tunnel (virtual private network).
The traditional IPsec protocol stack that has been installed with Openswan is the NETKEY.
NETKEY is a default Linux kernel which contains the daemons and the userland tools that are needed to set up Openswan.
