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 06/29/2025 PAM_USERDB(8)
Generated by dwww version 1.16 on Tue Dec 16 07:17:14 CET 2025.