The OPIUM package includes facilities which synchronize the cluster's accounts and configures ssh for users. The user account synchronization may only be run by root, and is automatically triggered at regular intervals. OPIUM configures ssh such that every user can traverse the cluster securely without entering a password, once logged on to the head node. This is done using ssh user keys, in the .ssh folder in your home directory. It is not recommended that you make changes here unless you know what you are doing. If you change your password, make sure to change it on the OSCAR head node, because changes propagate to the cluster nodes from there.