Kerberos can create cross-forest trust that defines a relationship between two otherwise separate domain forests.
A domain forest is a hierarchical structure of domains; both AD and {FreeIPA} constitute a forest.
With a trust relationship enabled between AD and {FreeIPA}, users of AD can access Linux hosts and services using a single set of credentials.
From the {Project} point of view, the configuration process is the same as integration with {FreeIPA} server without cross-forest trust configured. {ProjectServer} has to be enrolled in the IdM domain and integrated as described in [Using_FreeIPA_{context}].