If you run the dashboard as a non-root user, and try to login as other users on the system, it will not work. The problem is that as non-root, PAM can only verify the user's own password - not other users. This is a good description of the problem.

http://stackoverflow.com/questions/10910193/how-to-authenticate-username-password-using-pam-w-o-root-privileges

Reproducible with our code:

export PYTHONPATH=`pegasus-config --python`:`pegasus-config --python-externals`

import pam
pam.authenticate('someuser', 'somepasswd')

Where someuser is not the same on as your are running Python as.

Note that this is possibly dependent on the underlying user database. It will not work with a local user and shadow password.