| An ESXi host's configuration consists of configuration files for each service that runs on the host. The configuration files typically reside in the /etc/ directory, but they can also reside in other namespaces. The configuration files contain run-time information about the state of the services. Over time, the default values in the configuration files might change, for example, when settings on the ESXi host are changed.
A cron job backs up the ESXi configuration files periodically, when ESXi shuts down gracefully or on demand, and creates an archived configuration file in the boot bank. When ESXi reboots, it reads the archived configuration file and recreates the state that ESXi was in when the backup was taken.
Before vSphere 7.0 Update 2, the archived ESXi configuration file is not encrypted. In vSphere 7.0 Update 2 and later, the archived configuration file is encrypted. When the ESXi host is configured with a Trusted Platform Module (TPM), the TPM is used to "seal" the configuration to the host, providing a strong security guarantee and additional protection from offline attacks.
Configuration encryption uses the physical TPM when it is available and supported at install or upgrade time. If the TPM was added or enabled later, the ESXi host must be told to reconfigure to use the newly available TPM. Once the TPM configuration encryption is enabled, it cannot be disabled. |