Take the tour ×  I'm setting up key based authentication for SSH
on a new box, and was reading a few articles that mention
setting UsePAM to no along with PasswordAuthentication.  My
question is, what is the purpose of setting UsePAM to no if you
already have PasswordAuthentication and
ChallengeResponseAuthentication set to no?  share|improve this
question Hope this helps answer your question -- mail-
index.netbsd.org/tech-security/2009/01/04/msg000153.html – 
Chida Aug 17 '12 at 18:19 add comment  1 Answer  up vote 4 down
vote accepted  I think that people who recommend disabling
UsePAM may not understand completely the services provided by
the PAM stack. In addition to authentication, PAM also provides
session setup services that you may not want to bypass.
Examples include setting resource limits (via pam_limit),
environment variables, and mounting directories.  If it makes
you more comfortable you can modify the PAM configuration for
sshd such that it does not support password authentication of
any sort.