The NoLogin authentication component (
pam_sm_authenticate()), always returns success for the superuser, and returns success for all other users if the file
/etc/nologin does not exist. If
/etc/nologin does exist, then its contents are echoed to non-superusers before failure is returned. If a "nologin" capability is specified in
login.conf(5), then the file thus specified is used instead. This usually defaults to
/etc/nologin.
The following options may be passed to the authentication module:
debug
syslog(3) debugging information at
LOG_DEBUG level.
no_warn
suppress warning messages to the user. These messages include reasons why the user's authentication attempt was declined.