strongswan-plugin-kernel-libipsec 5.3.5-1ubuntu3.1 (amd64 binary) in ubuntu xenial

 The strongSwan VPN suite uses the native IPsec stack in the standard
 Linux kernel. It supports both the IKEv1 and IKEv2 protocols.
 .
 This package provides the strongSwan plugin which provides an IPsec backend
 that works entirely in userland, using TUN devices and strongSwan's own IPsec
 implementation libipsec. This is useful for when there is no kernel support for
 IPsec.
 .
 This plugin is now included in libcharon-extra-plugins. This package can
 be safely removed once it's installed.