Manual: pam_userdb

PAM_USERDB(8)					      Linux-PAM Manual					       PAM_USERDB(8)

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) 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. Note that password hashes, both from db and computed, will be printed to syslog.

       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), pam.conf(5), pam.d(5), pam(7)

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

Linux-PAM						 07/16/2026					       PAM_USERDB(8)