Assume that several machines with Unix-like OSs are connected to a server, which for example runs LDAP. Its database includes many users: one of them is
testuser. This way,
testuser can perform a login in any of the machines with the same credentials.
Assume now that
testuser successfully logged in
host1. Is it possible to make this login valid also for all the other hosts in the domain, so that, when
testuser tries to log in them, he is already authenticated?
This should work approximately the following way: each machine belonging to the domain is trusted. When a user logs in a machine, a check is performed if he/she has already logged in another machine of the domain; if no, a password (or key) is required; if yes, user is automatically authenticated also in the current machine.
Plan 9 offers something similar. Is it possible to obtain this with Unix-like OSs?
Edit: by login I mean the successful access to the system shell or GUI. Logins may occur remotely, through
ssh, as well as locally, through a keyboard. The authentication method should be password for a local access, password or key for
ssh. I would always consider the use of PAM.