PAM_ALREADYLOGGEDIN(8)
NAME
pam_alreadyloggedin -- Already-logged-in PAM module
SYNOPSIS
[service-name] module-type control-flag pam_alreadyloggedin [options]
DESCRIPTION
- The Already-logged-in authentication service module for PAM,
pam_alreadyloggedin 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 (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:
- auth required /lib/security/pam_securetty.so
auth sufficient /lib/security/pam_alreadyloggedin.so no_root
auth required /lib/security/pam_stack.so service=system-auth
BUGS
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.
SEE ALSO
fnmatch(3), getuid(2), stat(2), utmp(5), w(8), pam.conf(5), pam(8)
AUTHORS
Adopted for Linux PAM by Ilya Evseev at Jan 2004.
- The original pam_alreadyloggedin 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.