A method protects a technical installation that enables physical entry by persons to the installation and a computerized access to a computer device of the installation. Persons who have current access to the computer device are registered as persons accessing the computer device leading to a formation of registered computer user data, and persons who are present in the installation are registered as persons present on site leading to a formation of registered on-site data. In the event of a new desired entry or a new desired access, a plausibility check is carried out in which a check is made as to whether the desired entry is plausibly compatible with the registered computer user data or whether the desired access is plausibly compatible with the registered on-site data.