The Already-logged-in authentication service module for PAM,
provides functionality for only one PAM category:
authentication.
In terms of the
module-type
parameter, this is the
``auth
''
feature.
It also provides null functions for other PAM categories.
Already-logged-in Authentication Module
The Already-logged-in authentication component
(Fn pam_sm_authenticate
)
returns success if and only if the target user's ID is identical to a current login specified in the
utmp(5)
database and verified with matching permissions on that login's respective terminal in
/dev
If a user shows up in
w(8)
output, they will generally be allowed to authenticate using this method.
The following options may be passed to the authentication module:
debug
Enable verbose output to syslog at LOG_DEBUG level.
no_debug
Disable verbose output to syslog even it's enabled at compile time.
no_root
Never allow login with a target user ID of zero.
restrict_tty = ttyglob*
Only allow login if the terminal device currently being authenticated on matches
ttyglob*
The
ttyglob*
argument is specified as a shell glob, and checked using the
fnmatch(3)
function. For example,
restrict_tty=/dev/tty[1-6]
allows logging from text consoles of physical terminal only.
restrict_loggedin_tty = ttyglob*
Disallow recognition that the user is already logged in unless the terminal device logged in upon matches
ttyglob*
EXAMPLE
Modify
auth
section of the
/etc/pam.d/login
file like following:
Lp
FreeBSD version expects
/dev/
prefix in
restrict_tty
value, but value of
restrict_loggedin_tty
should be without them.
Linux version expects
/dev/
in both cases.
Adopted for Linux PAM by Ilya Evseev at Jan 2004.
Lp The original
module and this manual page were developed for the FreeBSD Project by
NAI Labs and ThinkSec AS, the Security Research Division of Network
Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035
(``CBOSS''
)
as part of the DARPA CHATS research program.