3.5. Certificate infrastructure#

The certificate infrastructure in a domain operated with Univention Corporate Server (UCS) ensures the trust context between all participants. The first domain node creates its own certificate authority (CA) for the domain. For more information see the Wikipedia article Certificate authority.

UCS uses Transport Layer Security (TLS). The UCS Primary Directory Node creates the CA on behalf of the domain during its installation and signs certificates for other systems that join the domain. All certificates have an expiration date. Backup Directory Nodes in the domain repeatedly pull all certificates from the Primary Domain Controller to allow administrators to promote one of them to a Primary Directory Node any time, if needed.

Services in the UCS domain also use the certificates created by UCS. Administrators can configure alternative certificates for end-user or internet facing services with certificates issued by third parties, for example Let’s Encrypt.

The domain systems use the certificates for secure communication between each other over the computer network, for example for domain database replication and the web interface of the UCS management system. Communication clients need to know the public key of the domain’s CA to validate the public key of the certificate.