pam_securetty - Limit root login to special devices

Author

       pam_securetty was written by Elliot Lee <sopwith@cuc.edu>.

Linux-PAM                                          07/03/2025                                   PAM_SECURETTY(8)

Description

       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 the securetty file. pam_securetty checks at first, if /etc/securetty exists.
       If not and it was built with vendordir support, it will use /securetty. pam_securetty also checks that
       the securetty files are plain files 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.

Examples

           auth  required  pam_securetty.so
           auth  required  pam_unix.so

Module Types Provided

       Only the auth module type is provided.

Name

       pam_securetty - Limit root login to special devices

Options

       debug
           Print debug information.

       noconsole
           Do not automatically allow root logins on the kernel console device, as specified on the kernel
           command line or by the sys file, if it is not also specified in the securetty file.

Return Values

       PAM_SUCCESS
           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.

       PAM_AUTH_ERR
           Authentication is rejected. Either root is attempting to log in via an unacceptable device, or the
           securetty file is world writable or not a normal file.

       PAM_BUF_ERR
           Memory buffer error.

       PAM_CONV_ERR
           The conversation method supplied by the application failed to obtain the username.

       PAM_INCOMPLETE
           The conversation method supplied by the application returned PAM_CONV_AGAIN.

       PAM_SERVICE_ERR
           An error occurred while the module was determining the user's name or tty, or the module could not
           open the securetty file.

       PAM_USER_UNKNOWN
           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.