SYNOPSIS

[service-name ] module-type control-flag pam_alreadyloggedin [options ]

DESCRIPTION

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

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

AUTHORS

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.