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.