IPSec is a suite of protocols, standards, and security algorithms that help secure traffic over unsecure and untrusted networks, such as the Internet. RFCs 4301 and 4309 describe IPSec in much more detail than covered here and can be found at the following locations:
The use of virtual private networks to securely transfer data among tenant and remote networks is a viable and recommended alternative to exposing the instances directly through the use of floating IPs. In this chapter, I demonstrated creating a VPN between two Neutron routers. Depending on the driver, it is possible to create tunnels between Neutron routers and physical VPN gateways, such as the Cisco ASA, Juniper SRX, and others.
As of Kilo, VPNaaS is no longer considered experimental. However, proposals to change the API to extend functionality are submitted, which may deprecate the methods and commands described here. Be sure to reference the OpenStack...