Citrix XenServer has many different use cases; including traditional server virtualisation for enterprise & SMB markets, through to being a platform for other Citrix products such as CloudPlatform and XenDesktop and other cloud and data-centre software applications.  Something often common across these disparate use cases is the question about security or compliance and how an organisation can ensure that their hosting infrastructure has not been tampered with.

For the past year, Citrix has worked closely with Intel® on adoption of their Trusted Execution Technology (TXT) functionality, bringing measured boot  capability to XenServer infrastructures.

This past week, Citrix announced general availability of two supplemental packs supporting Measured Boot, one each for XenServer v6.1 and v6.2 releases and available for download at

So what does this mean to your organisation and how does it aid in the security of workloads running on your cloud hypervisor platform?

Trusted computing in this space is typically comprised of three key components, (i) a hypervisor which measures the components and stores them in a secure location on the hardware platform, (ii) a remote attestation service for collecting measurements from the hypervisor for comparison against known good (whitelist) values and (iii) a higher level orchestration service that allows decision making based on the trust or compliance level of the hypervisor.

Consider the case for a configured known good XenServer trusted compute pool with a cloud orchestration layer configured above it.  If any host within that pool were to become comprised, the remote attestation layer would detect the difference between the known good measurement and the host’s current measurement, enabling the cloud orchestration layer to make intelligent security based decisions, such as isolation of the host, or perhaps limiting what workloads can run on it.

This makes it also very useful for reasons of compliance in highly regulated environments, such as ensuring business sensitive workloads are only allowed to run on hosting infrastructure you know not to have been tampered with, excluding any hosts that are not running a Measured Boot configuration and hence are in an unknown and unmeasured state.

With an Intel TXT enabled XenServer hypervisor platform, Citrix are now making it possible to create Trusted Compute Pool solutions with an increasing ecosystem of cloud solutions partners, such as with OpenStack.

Further reading:

Trusted Execution Technology (TXT) –

Trusted Platform Module (TPM) –