pam_securetty.so  [
        debug
      ]
      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.
    
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.
The user is allowed to continue authentication. Either the user is not root, or the root user is trying to log in on an acceptable device.
            Authentication is rejected. Either root is attempting to
            log in via an unacceptable device, or the
            /etc/securetty file is world writable or
            not a normal file.
          
An application error occurred. pam_securetty was not able to get information it required from the application that called it.
            An error occurred while the module was determining the
            user's name or tty, or the module could not open
            /etc/securetty.
          
            The module could not find the user name in the
            /etc/passwd file to verify whether
            the user had a UID of 0. Therefore, the results of running
            this module are ignored.