I have a warning message that is displayed to a user after they enter their username to log in to our Linux servers. I only want to display this message for password authentications, and not when keys are used. It should only show to a user who is logging into a host, and not when they are sshing from one host to another (our hosts all have keys set up so we can ssh from one to another without entering passwords).

Currently, I have a line for Banner in the /etc/ssh/sshd_config file which points to a text file containing the warning message. Banner doesn't appear to have any further config options, so I'm wondering if there is a way to do this with pam or some other mechanism? Thanks.