pam_securetty is a PAM module that allows root logins only if the
user is logging in on a "secure" tty, as defined by the listing
in /etc/securetty. pam_securetty also checks
to make sure that /etc/securetty is a plain
file and not world writable. It will also allow root logins on
the tty specified with console= switch on the
kernel command line and on ttys from the
/sys/class/tty/console/active.
This module has no effect on non-root users and requires that the
application fills in the PAM_TTY
item correctly.
For canonical usage, should be listed as a
required authentication method
before any sufficient
authentication methods.