Whenever a process of a parallel task is spawned within the cluster, ParaStation MPI does not authenticate the user. Only the user and group ID is copied to the remote node and used for starting up processes.

Thus, it is not necessary for the user to be known by the compute node, e.g. having an entry in /etc/passwd. On the contrary, the administrator may disallow logins for users by removing the entries from /etc/passwd. Usage of common authentication schemes like NIS is not required and therefore limits user management to the frontend nodes.

Authentication of users is restricted to login or frontend nodes and is outside of the scope of ParaStation MPI.