Case studies

Case studies

Earlier in Introduction to case studies we introduced the Alice and Bob case studies where Alice is deploying a private government cloud and Bob is deploying a public cloud each with different security requirements. Here we discuss how Alice and Bob would architect their clouds with respect to instance entropy, scheduling instances, trusted images, and instance migrations.

Alice’s private cloud

Earlier in Alice’s private cloud Alice issued a Request for Product (or RFP) to major hardware vendors that outlined her performance and form factor needs. This RFP includes the requirement for a processor architecture with rdrand support (currently Ivy Bridge or Haswell). When the hardware has been delivered and is being configured, Alice will use the entropy-gathering daemon (egd) in libvirt to ensure sufficient entropy and the ability to feed that entropy to instances. She also enables ‘trusted compute pools’ for boot time attestation of the image that will be compared to a hash from the ‘golden images.’ She configures the .bash_profile to log all commands, and sends those to the event monitoring collector. As users are expected to only have access to the application, and not the instance behind it, Alice installs a host intrusion detection system (HIDS) agent on the instance as well to monitor and export system events, and also ensures her internal public certificate is installed into the certificate store on the system. Alice is also aware that a side effect of this architecture is that Alice’s team will be expected to manage all of the instances in the environment.

Bob’s public cloud

Bob is aware that entropy will be a concern for some of his customers, such as those in the financial industry. However, due to the added cost and complexity, Bob has decided to forgo integrating hardware entropy into the first iteration of his cloud. He adds hardware entropy as a fast-follow to do for a later improvement for the second generation of his cloud architecture.

Bob is interested in ensuring that customers receive a high quality of service. He is concerned that providing excess explicit user control over instance scheduling could negatively impact the quality of service. As a result, he disables this feature. Bob provides images in the cloud from a known trusted source for users to use. Additionally, he allows users to upload their own images. However, users generally cannot share their images. This helps prevent a user from sharing a malicious image, which could negatively impact the security of other users in the cloud.

For migrations, Bob wants to enable secure instance migrations in order to support rolling upgrades with minimal user downtime. Bob ensures that all migrations occur on an isolated VLAN. He plans to defer implementing encrypted migrations until this is better supported in nova client tools. As a result, he makes a note to track this carefully and switch to encrypted migrations as soon as possible.

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