Internet Key Exchange daemon

 Openswan is an IPsec based VPN solution for the Linux kernel. It can use the
 native IPsec stack as well as the KLIPS kernel module. Both IKEv1 and IKEv2
 protocols are supported.
 .
 The Openswan IKE daemon is named pluto. It was inherited from the FreeS/WAN
 project, but provides improved X.509 certificate support and other features.
 .
 In order to use the KLIPS IPsec code instead of the native version, you will
 need to either install openswan-modules-source and build the appropriate
 module for your kernel or use openswan-modules-dkms which automates this
 task.