# phpman > man > pam_userdb(8)

[PAM_USERDB(8)](https://www.chedong.com/phpMan.php/man/PAMUSERDB/8/markdown)                             Linux-PAM Manual                             [PAM_USERDB(8)](https://www.chedong.com/phpMan.php/man/PAMUSERDB/8/markdown)



## NAME
       pam_userdb - PAM module to authenticate against a db database

## SYNOPSIS
       **pam**___**userdb.so** db=_/path/database_ [debug] [crypt=[crypt|none]] [icase] [dump] [try_first_pass]
                     [use_first_pass] [unknown_ok] [key_only]

## DESCRIPTION
       The pam_userdb module is used to verify a username/password pair against values stored in a
       Berkeley DB database. The database is indexed by the username, and the data fields
       corresponding to the username keys are the passwords.

## OPTIONS
### crypt=[crypt|none]
           Indicates whether encrypted or plaintext passwords are stored in the database. If it is
           **crypt**, passwords should be stored in the database in [**crypt**(3)](https://www.chedong.com/phpMan.php/man/crypt/3/markdown) form. If **none** is selected,
           passwords should be stored in the database as plaintext.

       **db=**_/path/database_
           Use the /path/database database for performing lookup. There is no default; the module
           will return **PAM**___**IGNORE** if no database is provided. Note that the path to the database
           file should be specified without the .db suffix.

### debug
           Print debug information.

### dump
           Dump all the entries in the database to the log. Don't do this by default!

### icase
           Make the password verification to be case insensitive (ie when working with registration
           numbers and such). Only works with plaintext password storage.

       **try**___**first**___**pass**
           Use the authentication token previously obtained by another module that did the
           conversation with the application. If this token can not be obtained then the module will
           try to converse. This option can be used for stacking different modules that need to deal
           with the authentication tokens.

       **use**___**first**___**pass**
           Use the authentication token previously obtained by another module that did the
           conversation with the application. If this token can not be obtained then the module will
           fail. This option can be used for stacking different modules that need to deal with the
           authentication tokens.

       **unknown**___**ok**
           Do not return error when checking for a user that is not in the database. This can be
           used to stack more than one pam_userdb module that will check a username/password pair in
           more than a database.

       **key**___**only**
           The username and password are concatenated together in the database hash as
           'username-password' with a random value. if the concatenation of the username and
           password with a dash in the middle returns any result, the user is valid. this is useful
           in cases where the username may not be unique but the username and password pair are.

## MODULE TYPES PROVIDED
       The **auth** and **account** module types are provided.

## RETURN VALUES
       PAM_AUTH_ERR
           Authentication failure.

       PAM_AUTHTOK_RECOVERY_ERR
           Authentication information cannot be recovered.

       PAM_BUF_ERR
           Memory buffer error.

       PAM_CONV_ERR
           Conversation failure.

       PAM_SERVICE_ERR
           Error in service module.

       PAM_SUCCESS
           Success.

       PAM_USER_UNKNOWN
           User not known to the underlying authentication module.

## EXAMPLES
           auth  sufficient pam_userdb.so icase db=/etc/dbtest


## SEE ALSO
       [**crypt**(3)](https://www.chedong.com/phpMan.php/man/crypt/3/markdown), [**pam.conf**(5)](https://www.chedong.com/phpMan.php/man/pam.conf/5/markdown), [**pam.d**(5)](https://www.chedong.com/phpMan.php/man/pam.d/5/markdown), [**pam**(7)](https://www.chedong.com/phpMan.php/man/pam/7/markdown)

## AUTHOR
       pam_userdb was written by Cristian Gafton ><gafton@redhat.com><.



Linux-PAM Manual                             06/08/2020                                [PAM_USERDB(8)](https://www.chedong.com/phpMan.php/man/PAMUSERDB/8/markdown)