Virtualization and its natural evolution, cloud computing, are young yet pervasive technologies. A fast-changing environment, where rules are rewritten every time a vendor releases a significant upgrade. Private Clouds are a relatively recent evolution, yet their management and deployment models have a significant impact on the security they can achieve at the moment and the level of security they will be able to offer in the future.In this talk, we will explore the virtualization security domain through the custom tools we've developed in the vasto suite and by a detailed analysis of existing technological solutions and their features... and failures.