SLAPO_PPOLICY(5) SLAPO_PPOLICY(5)
NAME
slapo-ppolicy – Password Policy overlay to slapd
SYNOPSIS
/etc/openldap/slapd.conf
DESCRIPTION
The ppolicy overlay is an implementation of the most recent IETF Password Policy proposal for LDAP. When
instantiated, it intercepts, decodes and applies specific password policy controls to overall use of a backend
database, changes to user password fields, etc.
The overlay provides a variety of password control mechanisms. They include password aging -- both minimum and
maximum ages, password reuse and duplication control, account time-outs, mandatory password resets, acceptable
password content, and even grace logins. Different groups of users may be associated with different password
policies, and there is no limit to the number of password policies that may be created.
Note that some of the policies do not take effect when the operation is performed with the rootdn identity; all
the operations, when performed with any other identity, may be subjected to constraints, like access control.
Note that the IETF Password Policy proposal for LDAP makes sense when considering a single-valued password
attribute, while the userPassword attribute allows multiple values. This implementation enforces a single value
for the userPassword attribute, despite its specification.
CONFIGURATION
These slapd.conf configuration options apply to the ppolicy overlay. They should appear after the overlay direc-
tive.
<strong>ppolicy_default <policyDN></strong>
Specify the DN of the pwdPolicy object to use when no specific policy is set on a given user’s entry. If
there is no specific policy for an entry and no default is given, then no policies will be enforced.
ppolicy_forward_updates
Specify that policy state changes that result from Bind operations (such as recording failures, lockout,
etc.) on a consumer should be forwarded to a master instead of being written directly into the consumer’s
local database. This setting is only useful on a replication consumer, and also requires the updateref
setting and chain overlay to be appropriately configured.
ppolicy_hash_cleartext
Specify that cleartext passwords present in Add and Modify requests should be hashed before being stored
in the database. This violates the X.500/LDAP information model, but may be needed to compensate for LDAP
clients that don’t use the Password Modify extended operation to manage passwords. It is recommended that
when this option is used that compare, search, and read access be denied to all directory users.
ppolicy_use_lockout
A client will always receive an LDAP InvalidCredentials response when Binding to a locked account. By
default, when a Password Policy control was provided on the Bind request, a Password Policy response will
be included with no special error code set. This option changes the Password Policy response to include
the AccountLocked error code. Note that sending the AccountLocked error code provides useful information
to an attacker; sites that are sensitive to security issues should not enable this option.
OBJECT CLASS
The ppolicy overlay depends on the pwdPolicy object class. The definition of that class is as follows:
( 1.3.6.1.4.1.42.2.27.8.2.1
NAME ’pwdPolicy’
AUXILIARY
SUP top
MUST ( pwdAttribute )
MAY (
pwdMinAge $ pwdMaxAge $ pwdInHistory $
pwdCheckQuality $ pwdMinLength $
pwdExpireWarning $ pwdGraceAuthnLimit $
pwdLockout $ pwdLockoutDuration $
pwdMaxFailure $ pwdFailureCountInterval $
pwdMustChange $ pwdAllowUserChange $
pwdSafeModify ) )
This implementation also provides an additional pwdPolicyChecker objectclass, used for password quality checking
(see below).
( 1.3.6.1.4.1.4754.2.99.1
NAME ’pwdPolicyChecker’
AUXILIARY
SUP top
MAY ( pwdCheckModule ) )
Every account that should be subject to password policy control should have a pwdPolicySubentry attribute con-
taining the DN of a valid pwdPolicy entry, or they can simply use the configured default. In this way different
users may be managed according to different policies.
OBJECT CLASS ATTRIBUTES
Each one of the sections below details the meaning and use of a particular attribute of this pwdPolicy object
class.
<strong>pwdAttribute</strong>
This attribute contains the name of the attribute to which the password policy is applied. For example, the pass-
word policy may be applied to the userPassword attribute.
Note: in this implementation, the only value accepted for pwdAttribute is userPassword .
( 1.3.6.1.4.1.42.2.27.8.1.1
NAME ’pwdAttribute’
EQUALITY objectIdentifierMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.38 )
<strong>pwdMinAge</strong>
This attribute contains <strong>the number of seconds that must elapse between modifications allowed to the password.</strong> If
this attribute is not present, zero seconds is assumed (i.e. the password may be modified whenever and however
often is desired).
( 1.3.6.1.4.1.42.2.27.8.1.2
NAME ’pwdMinAge’
EQUALITY integerMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
SINGLE-VALUE )
<strong>pwdMaxAge</strong>
This attribute contains <strong>the number of seconds after which a modified password will expire.</strong> If this attribute is
not present, or if its value is zero (0), then passwords will not expire.
( 1.3.6.1.4.1.42.2.27.8.1.3
NAME ’pwdMaxAge’
EQUALITY integerMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
SINGLE-VALUE )
<strong>pwdInHistory</strong>
This attribute is used <strong>to specify the maximum number of used passwords that will be stored in the pwdHistory
attribute.</strong> If the pwdInHistory attribute is not present, or if its value is zero (0), used passwords will not be
stored in pwdHistory and thus any previously-used password may be reused. No history checking occurs if the
password is being modified by the rootdn, although the password is saved in the history.
( 1.3.6.1.4.1.42.2.27.8.1.4
NAME ’pwdInHistory’
EQUALITY integerMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
SINGLE-VALUE )
<strong>pwdCheckQuality</strong>
This attribute indicates if and how password syntax <strong>will be checked while a password is being modified or added.
If this attribute is not present, or its value is zero (0), no syntax checking will be done. If its value is one
(1), the server will check the syntax, and if the server is unable to check the syntax, whether due to a client-
side hashed password or some other reason, it will be accepted. If its value is two (2), the server will check
the syntax, and if the server is unable to check the syntax it will return an error refusing the password.</strong>
( 1.3.6.1.4.1.42.2.27.8.1.5
NAME ’pwdCheckQuality’
EQUALITY integerMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
SINGLE-VALUE )
<strong>pwdMinLength</strong>
When syntax checking is enabled (see also the pwdCheckQuality attribute), this attribute contains <strong>the minimum
number of characters that will be accepted in a password.</strong> If this attribute is not present, minimum password
length is not enforced. If the server is unable to check the length of the password, whether due to a client-side
hashed password or some other reason, the server will, depending on the value of pwdCheckQuality, either accept
the password without checking it (if pwdCheckQuality is zero (0) or one (1)) or refuse it (if pwdCheckQuality is
two (2)).
( 1.3.6.1.4.1.42.2.27.8.1.6
NAME ’pwdMinLength’
EQUALITY integerMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
SINGLE-VALUE )
<strong>pwdExpireWarning</strong>
This attribute contains <strong>the maximum number of seconds before a password is due to expire that expiration warning
messages will be returned to a user who is authenticating to the directory.</strong> If this attribute is not present, or
if the value is zero (0), no warnings will be sent.
( 1.3.6.1.4.1.42.2.27.8.1.7
NAME ’pwdExpireWarning’
EQUALITY integerMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
SINGLE-VALUE )
pwdGraceAuthnLimit
This attribute contains the number of times that an expired password may be used to authenticate a user to the
directory. If this attribute is not present or if its value is zero (0), users with expired passwords will not be
allowed to authenticate to the directory.
( 1.3.6.1.4.1.42.2.27.8.1.8
NAME ’pwdGraceAuthnLimit’
EQUALITY integerMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
SINGLE-VALUE )
<strong>pwdLockout</strong>
This attribute specifies the action that should be taken by the directory when a user has made a number of failed
attempts to authenticate to the directory. If pwdLockout is set (its value is "TRUE"), the user will not be
allowed to attempt to authenticate to the directory after there have been a specified number of consecutive
failed bind attempts. The maximum number of consecutive failed bind attempts allowed is specified by the pwdMax-
Failure attribute. If pwdLockout is not present, or if its value is "FALSE", the password may be used to authen-
ticate no matter how many consecutive failed bind attempts have been made.
( 1.3.6.1.4.1.42.2.27.8.1.9
NAME ’pwdLockout’
EQUALITY booleanMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.7
SINGLE-VALUE )
<strong>pwdLockoutDuration</strong>
This attribute contains the number of seconds during which the password cannot be used to authenticate the user
to the directory due to too many consecutive failed bind attempts. (See also pwdLockout and pwdMaxFailure.) If
pwdLockoutDuration is not present, or if its value is zero (0), the password cannot be used to authenticate the
user to the directory again until it is reset by an administrator.
( 1.3.6.1.4.1.42.2.27.8.1.10
NAME ’pwdLockoutDuration’
EQUALITY integerMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
SINGLE-VALUE )
pwdMaxFailure
This attribute contains the number of consecutive failed bind attempts after which the password may not be used
to authenticate a user to the directory. If pwdMaxFailure is not present, or its value is zero (0), then a user
will be allowed to continue to attempt to authenticate to the directory, no matter how many consecutive failed
bind attempts have occurred with that user’s DN. (See also pwdLockout and pwdLockoutDuration.)
( 1.3.6.1.4.1.42.2.27.8.1.11
NAME ’pwdMaxFailure’
EQUALITY integerMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
SINGLE-VALUE )
pwdFailureCountInterval
This attribute contains the number of seconds after which old consecutive failed bind attempts are purged from
the failure counter, even though no successful authentication has occurred. If pwdFailureCountInterval is not
present, or its value is zero (0), the failure counter will only be reset by a successful authentication.
( 1.3.6.1.4.1.42.2.27.8.1.12
NAME ’pwdFailureCountInterval’
EQUALITY integerMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.27
SINGLE-VALUE )
<strong>pwdMustChange</strong>
This attribute specifies whether users must change their passwords when they first bind to the directory after a
password is set or reset by the administrator, or not. If pwdMustChange has a value of "TRUE", users must change
their passwords when they first bind to the directory after a password is set or reset by the administrator. If
pwdMustChange is not present, or its value is "FALSE", users are not required to change their password upon bind-
ing after the administrator sets or resets the password.
( 1.3.6.1.4.1.42.2.27.8.1.13
NAME ’pwdMustChange’
EQUALITY booleanMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.7
SINGLE-VALUE )
<strong>pwdAllowUserChange</strong>
This attribute specifies whether users are <strong>allowed to change their own passwords or not.</strong> If pwdAllowUserChange
is set to "TRUE", or if the attribute is not present, users will be allowed to change their own passwords. If
its value is "FALSE", users will not be allowed to change their own passwords.
( 1.3.6.1.4.1.42.2.27.8.1.14
NAME ’pwdAllowUserChange’
EQUALITY booleanMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.7
SINGLE-VALUE )
<strong>pwdSafeModify</strong>
This attribute denotes whether<strong> the user’s existing password must be sent along with their new password when
changing a password.</strong> If pwdSafeModify is set to "TRUE", the existing password must be sent along with the new
password. If the attribute is not present, or its value is "FALSE", the existing password need not be sent along
with the new password.
( 1.3.6.1.4.1.42.2.27.8.1.15
NAME ’pwdSafeModify’
EQUALITY booleanMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.7
SINGLE-VALUE )
pwdCheckModule
This attribute names a user-defined loadable module that must instantiate the check_password() function. This
function will be called to further check a new password if pwdCheckQuality is set to one (1) or two (2), after
all of the built-in password compliance checks have been passed. This function will be called according to this
function prototype:
int check_password (char *pPasswd, char **ppErrStr, Entry *pEntry);
The pPasswd parameter contains the clear-text user password, the ppErrStr parameter contains a double pointer
that allows the function to return human-readable details about any error it encounters. The optional pEntry
parameter, if non-NULL, carries a pointer to the entry whose password is being checked. If ppErrStr is NULL,
then funcName must NOT attempt to use it/them. A return value of LDAP_SUCCESS from the called function indicates
that the password is ok, any other value indicates that the password is unacceptable. If the password is unac-
ceptable, the server will return an error to the client, and ppErrStr may be used to return a human-readable tex-
tual explanation of the error. The error string must be dynamically allocated as it will be free()’d by slapd.
( 1.3.6.1.4.1.4754.1.99.1
NAME ’pwdCheckModule’
EQUALITY caseExactIA5Match
SYNTAX 1.3.6.1.4.1.1466.115.121.1.26
SINGLE-VALUE )
Note: The user-defined loadable module named by pwdCheckModule must be in slapd’s standard executable search
PATH.
Note: pwdCheckModule is a non-standard extension to the LDAP password policy proposal.
OPERATIONAL ATTRIBUTES
The operational attributes used by the ppolicy module are stored in the user’s entry. Most of these attributes
are not intended to be changed directly by users; they are there to track user activity. They have been detailed
here so that administrators and users can both understand the workings of the ppolicy module.
Note that the current IETF Password Policy proposal does not define how these operational attributes are expected
to behave in a replication environment. In general, authentication attempts on a slave server only affect the
copy of the operational attributes on that slave and will not affect any attributes for a user’s entry on the
master server. Operational attribute changes resulting from authentication attempts on a master server will usu-
ally replicate to the slaves (and also overwrite any changes that originated on the slave). These behaviors are
not guaranteed and are subject to change when a formal specification emerges.
userPassword
The userPassword attribute is not strictly part of the ppolicy module. It is, however, the attribute that is
tracked and controlled by the module. Please refer to the standard OpenLDAP schema for its definition.
pwdPolicySubentry
This attribute refers directly to the pwdPolicy subentry that is to be used for this particular directory user.
If pwdPolicySubentry exists, it must contain the DN of a valid pwdPolicy object. If it does not exist, the ppol-
icy module will enforce the default password policy rules on the user associated with this authenticating DN. If
there is no default, or the referenced subentry does not exist, then no policy rules will be enforced.
( 1.3.6.1.4.1.42.2.27.8.1.23
NAME ’pwdPolicySubentry’
DESC ’The pwdPolicy subentry in effect for
this object’
EQUALITY distinguishedNameMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.12
SINGLE-VALUE
NO-USER-MODIFICATION
USAGE directoryOperation)
pwdChangedTime
This attribute denotes the last time that the entry’s password was changed. This value is used by the password
expiration policy to determine whether the password is too old to be allowed to be used for user authentication.
If pwdChangedTime does not exist, the user’s password will not expire.
( 1.3.6.1.4.1.42.2.27.8.1.16
NAME ’pwdChangedTime’
DESC ’The time the password was last changed’
SYNTAX 1.3.6.1.4.1.1466.115.121.1.24
EQUALITY generalizedTimeMatch
ORDERING generalizedTimeOrderingMatch
SINGLE-VALUE
NO-USER-MODIFICATION
USAGE directoryOperation)
pwdAccountLockedTime
This attribute contains the time that the user’s account was locked. If the account has been locked, the pass-
word may no longer be used to authenticate the user to the directory. If pwdAccountLockedTime is set to
000001010000Z, the user’s account has been permanently locked and may only be unlocked by an administrator. Note
that account locking only takes effect when the pwdLockout password policy attribute is set to "TRUE".
( 1.3.6.1.4.1.42.2.27.8.1.17
NAME ’pwdAccountLockedTime’
DESC ’The time an user account was locked’
SYNTAX 1.3.6.1.4.1.1466.115.121.1.24
EQUALITY generalizedTimeMatch
ORDERING generalizedTimeOrderingMatch
SINGLE-VALUE
NO-USER-MODIFICATION
USAGE directoryOperation)
pwdFailureTime
This attribute contains the timestamps of each of the consecutive authentication failures made upon attempted
authentication to this DN (i.e. account). If too many timestamps accumulate here (refer to the pwdMaxFailure
password policy attribute for details), and the pwdLockout password policy attribute is set to "TRUE", the
account may be locked. (Please also refer to the pwdLockout password policy attribute.) Excess timestamps
beyond those allowed by pwdMaxFailure may also be purged. If a successful authentication is made to this DN
(i.e. to this user account), then pwdFailureTime will be cleansed of entries.
( 1.3.6.1.4.1.42.2.27.8.1.19
NAME ’pwdFailureTime’
DESC ’The timestamps of the last consecutive
authentication failures’
SYNTAX 1.3.6.1.4.1.1466.115.121.1.24
EQUALITY generalizedTimeMatch
ORDERING generalizedTimeOrderingMatch
NO-USER-MODIFICATION
USAGE directoryOperation )
<strong>pwdHistory</strong>
This attribute contains the history of previously used passwords for this DN (i.e. for this user account). The
values of this attribute are stored in string format as follows:
pwdHistory=
time "#" syntaxOID "#" length "#" data
time=
GeneralizedTime as specified in section 3.3.13 of [RFC4517]
syntaxOID = numericoid
This is the string representation of the dotted-decimal OID that defines the syntax used to store the
password. numericoid is described in section 1.4 of [RFC4512].
length = NumericString
The number of octets in the data. NumericString is described in section 3.3.23 of [RFC4517].
data =
Octets representing the password in the format specified by syntaxOID.
This format allows the server to store and transmit a history of passwords that have been used. In order for
equality matching on the values in this attribute to function properly, the time field is in GMT format.
( 1.3.6.1.4.1.42.2.27.8.1.20
NAME ’pwdHistory’
DESC ’The history of user passwords’
SYNTAX 1.3.6.1.4.1.1466.115.121.1.40
EQUALITY octetStringMatch
NO-USER-MODIFICATION
USAGE directoryOperation)
pwdGraceUseTime This attribute contains the list of timestamps of logins made after the user password in the DN
has expired. These post-expiration logins are known as "grace logins". If too many grace logins have been used
(please refer to the pwdGraceLoginLimit password policy attribute), then the DN will no longer be allowed to be
used to authenticate the user to the directory until the administrator changes the DN’s userPassword attribute.
( 1.3.6.1.4.1.42.2.27.8.1.21
NAME ’pwdGraceUseTime’
DESC ’The timestamps of the grace login once the password has expired’
SYNTAX 1.3.6.1.4.1.1466.115.121.1.24
EQUALITY generalizedTimeMatch
NO-USER-MODIFICATION
USAGE directoryOperation)
pwdReset
This attribute indicates whether the user’s password has been reset by the administrator and thus must be changed
upon first use of this DN for authentication to the directory. If pwdReset is set to "TRUE", then the password
was reset and the user must change it upon first authentication. If the attribute does not exist, or is set to
"FALSE", the user need not change their password due to administrative reset.
( 1.3.6.1.4.1.42.2.27.8.1.22
NAME ’pwdReset’
DESC ’The indication that the password has
been reset’
EQUALITY booleanMatch
SYNTAX 1.3.6.1.4.1.1466.115.121.1.7
SINGLE-VALUE
USAGE directoryOperation)
EXAMPLES
database bdb
suffix dc=example,dc=com
…
overlay ppolicy
ppolicy_default “cn=Standard,ou=Policies,dc=example,dc=com”
SEE ALSO
ldap(3), slapd.conf(5), slapd-config(5), slapo-chain(5).
"OpenLDAP Administrator’s Guide" (http://www.OpenLDAP.org/doc/admin/)
IETF LDAP password policy proposal by P. Behera, L. Poitou and J. Sermersheim: documented in IETF document
"draft-behera-ldap-password-policy-09.txt".
BUGS
The LDAP Password Policy specification is not yet an approved standard, and it is still evolving. This code will
continue to be in flux until the specification is finalized.
ACKNOWLEDGEMENTS
This module was written in 2004 by Howard Chu of Symas Corporation with significant input from Neil Dunbar and
Kartik Subbarao of Hewlett-Packard.
This manual page borrows heavily and shamelessly from the specification upon which the password policy module it
describes is based. This source is the IETF LDAP password policy proposal by P. Behera, L. Poitou and J. Serm-
ersheim. The proposal is fully documented in the IETF document named draft-behera-ldap-password-policy-09.txt,
written in July of 2005.
OpenLDAP Software is developed and maintained by The OpenLDAP Project <http://www.openldap.org/>. OpenLDAP Soft-
ware is derived from University of Michigan LDAP 3.3 Release.
OpenLDAP 2.4.23 2010/06/30 SLAPO_PPOLICY(5)
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