--- /dev/null
+#
+# /etc/pam.d/common-auth - authentication settings common to all services
+#
+# This file is included from other service-specific PAM config files,
+# and should contain a list of the authentication modules that define
+# the central authentication scheme for use on the system
+# (e.g., /etc/shadow, LDAP, Kerberos, etc.). The default is to use the
+# traditional Unix authentication mechanisms.
+#
+auth required pam_unix.so nullok_secure