The UNIX authentication service module for PAM provides
functionality for two PAM categories: authentication and account management.
In terms of the module-type parameter, they are the
“auth
” and
“account
” features. It also provides a
null function for session management.
UNIX Ss Authentication Module
The UNIX authentication component provides functions to
verify the identity of a user (pam_sm_authenticate
()),
which obtains the relevant
passwd(5) entry. It prompts the
user for a password and verifies that this is correct with
crypt(3).
The following options may be passed to the authentication
module:
debug
- syslog(3) debugging
information at
LOG_DEBUG
level.
use_first_pass
- If the authentication module is not the first in the stack, and a previous
module obtained the user's password, that password is used to authenticate
the user. If this fails, the authentication module returns failure without
prompting the user for a password. This option has no effect if the
authentication module is the first in the stack, or if no previous modules
obtained the user's password.
try_first_pass
- This option is similar to the
use_first_pass
option, except that if the previously obtained password fails, the user is
prompted for another password.
auth_as_self
- This option will require the user to authenticate himself as the user
given by getlogin(2), not
as the account they are attempting to access. This is primarily for
services like su(1), where the
user's ability to retype their own password might be deemed
sufficient.
nullok
- If the password database has no password for the entity being
authenticated, then this option will forgo password prompting, and
silently allow authentication to succeed.
UNIX Ss Account Management Module
The UNIX account management component provides a
function to perform account management,
pam_sm_acct_mgmt
(). The function verifies that the
authenticated user is allowed to login to the local user account by checking
the password expiry date.
The following options may be passed to the management module:
debug
- syslog(3) debugging
information at
LOG_DEBUG
level.
UNIX Ss Password Management Module
The UNIX password management component provides a
function to perform account management,
pam_sm_chauthtok
(). The function changes the user's
password.
The following options may be passed to the password module:
debug
- syslog(3) debugging
information at
LOG_DEBUG
level.
no_warn
- suppress warning messages to the user. These messages include reasons why
the user's authentication attempt was declined.
passwd_db
=name
- Change the user's password only the specified password database. Valid
password database names are:
- files
- local password file
- nis
- NIS password database