VM Migration Support for Secure Out-of-Band VNC with Shadow Devices

Out-of-band VNC (OOB-VNC) enables users to remotely manage the systems in virtual machines (VMs) without relying on the target systems. It directly accesses VMs' virtual devices, but existing clouds do not protect them sufficiently. Therefore, secure OOB-VNC has been proposed. It runs shadow devices outside the virtualized system and securely accesses the shadow devices. However, users cannot use this management method with VM migration because traditional VM migration cannot deal with shadow devices. This paper proposes SDmigrate, which continues secure OOB-VNC after VMs are migrated. SDmigrate enables saving and restoring the states of shadow devices transparently via fake devices. A fake device communicates with the corresponding shadow device. In addition to the internal states of a shadow keyboard, mouse, and video card, SDmigrate deals with the external state of a shadow video card, i.e., the video memory in a migrated VM. We have implemented SDmigrate in Xen and confirmed that the degradation of migration performance was negligible.