This brief overview assumes that Openstack Havana has been installed and setup with Neutron Networking. If you have not already done this, you could use "https://github.com/cloudnull/rcbops_allinone_inone" or devstack to setup a dev box and then perform the following actions.
install "openswan":
# (apt-get install openswan neutron-plugin-vpn-agent) || (yum install openswan openstack-neutron-vpn-agent && chkconfig neutron-vpn-agent on)