pam_unix(8) - Manual pages

SYNOPSIS

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

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: