Chapitre 8. Ensuring system integrity with Keylime
With Keylime, you can continuously monitor the integrity of remote systems and verify the state of systems at boot. You can also send encrypted files to the monitored systems, and specify automated actions triggered whenever a monitored system fails the integrity test.
8.1. How Keylime works
You can deploy Keylime agents to perform one or more of the following actions:
- Runtime integrity monitoring
- Keylime runtime integrity monitoring continuously monitors the system on which the agent is deployed and measures the integrity of the files included in the allowlist and not included in the excludelist.
- Measured boot
- Keylime measured boot verifies the system state at boot.
Keylime’s concept of trust is based on the Trusted Platform Module (TPM) technology. A TPM is a hardware, firmware, or virtual component with integrated cryptographic keys. By polling TPM quotes and comparing the hashes of objects, Keylime provides initial and runtime monitoring of remote systems.
Keylime running in a virtual machine or using a virtual TPM depends upon the integrity of the underlying host. Ensure you trust the host environment before relying upon Keylime measurements in a virtual environment.
Keylime consists of three main components:
- The verifier initially and continuously verifies the integrity of the systems that run the agent.
- The registrar contains a database of all agents and it hosts the public keys of the TPM vendors.
- The agent is the component deployed to remote systems measured by the verifier.
In addition, Keylime uses the keylime_tenant utility for many functions, including provisioning the agents on the target systems.
Figure 8.1. Connections between Keylime components through configurations
Keylime ensures the integrity of the monitored systems in a chain of trust by using keys and certificates exchanged between the components and the tenant. For a secure foundation of this chain, use a certificate authority (CA) that you can trust.
If the agent receives no key and certificate, it generates a key and a self-signed certificate with no involvement from the CA.
Figure 8.2. Connections between Keylime components certificates and keys
