slapo−ppolicy — Password Policy overlay to slapd
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
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 options apply to the ppolicy overlay. They
should appear after the
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.
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
to be appropriately configured.
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.
A client will always receive an LDAP
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
code. Note that sending the
code provides useful information to an attacker; sites
that are sensitive to security issues should not enable
overlay depends on the
pwdPolicy object class. The
definition of that class is as follows:
( 18.104.22.168.22.214.171.124.126.96.36.199 NAME 'pwdPolicy' AUXILIARY SUP top MUST ( pwdAttribute ) MAY ( pwdMinAge $ pwdMaxAge $ pwdInHistory $ pwdCheckQuality $ pwdMinLength $ pwdExpireWarning $ pwdGraceAuthnLimit $ pwdLockout $ pwdLockoutDuration $ pwdMaxFailure $ pwdFailureCountInterval $ pwdMustChange $ pwdAllowUserChange $ pwdSafeModify 4 pwdMaxRecordedFailure ) )
This implementation also provides an additional
used for password quality checking (see below).
( 188.8.131.52.4.1.47184.108.40.206 NAME 'pwdPolicyChecker' AUXILIARY SUP top MAY ( pwdCheckModule ) )
Every account that should be subject to password policy
control should have a
containing 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.
Each one of the sections below details the meaning and use
of a particular attribute of this
pwdPolicy object class.
This attribute contains the name of the attribute to which
the password policy is applied. For example, the password
policy may be applied to the
In this implementation, the only value accepted
( 220.127.116.11.18.104.22.168.22.214.171.124 NAME 'pwdAttribute' EQUALITY objectIdentifierMatch SYNTAX 126.96.36.199.4.1.14188.8.131.52.38 )
This attribute contains the number of seconds that must elapse between modifications allowed to the password. If this attribute is not present, zero seconds is assumed (i.e. the password may be modified whenever and however often is desired).
( 184.108.40.206.220.127.116.11.18.104.22.168 NAME 'pwdMinAge' EQUALITY integerMatch SYNTAX 22.214.171.124.4.1.14126.96.36.199.27 SINGLE−VALUE )
This attribute contains the number of seconds after which a modified password will expire. If this attribute is not present, or if its value is zero (0), then passwords will not expire.
( 188.8.131.52.184.108.40.206.220.127.116.11 NAME 'pwdMaxAge' EQUALITY integerMatch SYNTAX 18.104.22.168.4.1.1422.214.171.124.27 SINGLE−VALUE )
This attribute is used to specify the maximum number of
used passwords that will be stored in the
pwdHistory attribute. If the
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.
( 126.96.36.199.188.8.131.52.184.108.40.206 NAME 'pwdInHistory' EQUALITY integerMatch SYNTAX 220.127.116.11.4.1.1418.104.22.168.27 SINGLE−VALUE )
This attribute indicates if and how password syntax 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.
( 22.214.171.124.126.96.36.199.188.8.131.52 NAME 'pwdCheckQuality' EQUALITY integerMatch SYNTAX 184.108.40.206.4.1.14220.127.116.11.27 SINGLE−VALUE )
When syntax checking is enabled (see also the
this attribute contains the minimum number of characters that
will be accepted in a password. 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
accept the password without checking it (if
pwdCheckQuality is zero (0)
or one (1)) or refuse it (if
pwdCheckQuality is two
( 18.104.22.168.22.214.171.124.126.96.36.199 NAME 'pwdMinLength' EQUALITY integerMatch SYNTAX 188.8.131.52.4.1.14184.108.40.206.27 SINGLE−VALUE )
This attribute contains 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. If this attribute is not present, or if the value is zero (0), no warnings will be sent.
( 220.127.116.11.18.104.22.168.22.214.171.124 NAME 'pwdExpireWarning' EQUALITY integerMatch SYNTAX 126.96.36.199.4.1.14188.8.131.52.27 SINGLE−VALUE )
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.
( 184.108.40.206.220.127.116.11.18.104.22.168 NAME 'pwdGraceAuthnLimit' EQUALITY integerMatch SYNTAX 22.214.171.124.4.1.14126.96.36.199.27 SINGLE−VALUE )
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
pwdMaxFailure attribute. If
pwdLockout is not
present, or if its value is "FALSE", the password may be used
to authenticate no matter how many consecutive failed bind
attempts have been made.
( 188.8.131.52.184.108.40.206.220.127.116.11 NAME 'pwdLockout' EQUALITY booleanMatch SYNTAX 18.104.22.168.4.1.1422.214.171.124.7 SINGLE−VALUE )
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.
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.
( 126.96.36.199.188.8.131.52.184.108.40.206 NAME 'pwdLockoutDuration' EQUALITY integerMatch SYNTAX 220.127.116.11.4.1.1418.104.22.168.27 SINGLE−VALUE )
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
( 22.214.171.124.126.96.36.199.188.8.131.52 NAME 'pwdMaxFailure' EQUALITY integerMatch SYNTAX 184.108.40.206.4.1.14220.127.116.11.27 SINGLE−VALUE )
This attribute contains the maximum number of failed bind
attempts to store in a user's entry. If
pwdMaxRecordedFailure is not
present, or its value is zero (0), then it defaults to the
pwdMaxFailure. If that value
is also 0, the default is 5.
( 18.104.22.168.22.214.171.124.126.96.36.199 NAME 'pwdMaxRecordedFailure' EQUALITY integerMatch SYNTAX 188.8.131.52.4.1.14184.108.40.206.27 SINGLE−VALUE )
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
not present, or its value is zero (0), the failure counter
will only be reset by a successful authentication.
( 220.127.116.11.18.104.22.168.22.214.171.124 NAME 'pwdFailureCountInterval' EQUALITY integerMatch SYNTAX 126.96.36.199.4.1.14188.8.131.52.27 SINGLE−VALUE )
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 binding after the administrator sets or
resets the password.
( 184.108.40.206.220.127.116.11.18.104.22.168 NAME 'pwdMustChange' EQUALITY booleanMatch SYNTAX 22.214.171.124.4.1.14126.96.36.199.7 SINGLE−VALUE )
This attribute specifies whether users are allowed to
change their own passwords or not. 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
This implies that when
( 188.8.131.52.184.108.40.206.220.127.116.11 NAME 'pwdAllowUserChange' EQUALITY booleanMatch SYNTAX 18.104.22.168.4.1.1422.214.171.124.7 SINGLE−VALUE )
This attribute denotes whether the user's existing
password must be sent along with their new password when
changing a password. 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.
( 126.96.36.199.188.8.131.52.184.108.40.206 NAME 'pwdSafeModify' EQUALITY booleanMatch SYNTAX 220.127.116.11.4.1.1418.104.22.168.7 SINGLE−VALUE )
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:
check_password(char *pPasswd, char **ppErrStr, Entry *pEntry);
parameter contains the clear-text user password, the
contains a double pointer that allows the function to return
human-readable details about any error it encounters. The
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 unacceptable, the server will return an error
to the client, and
ppErrStr may be used to
return a human-readable textual explanation of the error. The
error string must be dynamically allocated as it will be
free()'d by slapd.
( 22.214.171.124.4.1.47126.96.36.199 NAME 'pwdCheckModule' EQUALITY caseExactIA5Match SYNTAX 188.8.131.52.4.1.14184.108.40.206.26 SINGLE−VALUE )
The user-defined loadable module named by
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
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 usually 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.
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
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
ppolicy 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
( 220.127.116.11.18.104.22.168.22.214.171.124 NAME 'pwdPolicySubentry' DESC 'The pwdPolicy subentry in effect for this object' EQUALITY distinguishedNameMatch SYNTAX 126.96.36.199.4.1.14188.8.131.52.12 SINGLE−VALUE NO−USER−MODIFICATION USAGE directoryOperation)
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
not exist, the user's password will not expire.
( 184.108.40.206.220.127.116.11.18.104.22.168 NAME 'pwdChangedTime' DESC 'The time the password was last changed' SYNTAX 22.214.171.124.4.1.14126.96.36.199.24 EQUALITY generalizedTimeMatch ORDERING generalizedTimeOrderingMatch SINGLE−VALUE NO−USER−MODIFICATION USAGE directoryOperation)
This attribute contains the time that the user's account
was locked. If the account has been locked, the password may
no longer be used to authenticate the user to the directory.
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".
( 188.8.131.52.184.108.40.206.220.127.116.11 NAME 'pwdAccountLockedTime' DESC 'The time an user account was locked' SYNTAX 18.104.22.168.4.1.1422.214.171.124.24 EQUALITY generalizedTimeMatch ORDERING generalizedTimeOrderingMatch SINGLE−VALUE NO−USER−MODIFICATION USAGE directoryOperation)
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
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.
( 126.96.36.199.188.8.131.52.184.108.40.206 NAME 'pwdFailureTime' DESC 'The timestamps of the last consecutive authentication failures' SYNTAX 220.127.116.11.4.1.1418.104.22.168.24 EQUALITY generalizedTimeMatch ORDERING generalizedTimeOrderingMatch NO−USER−MODIFICATION USAGE directoryOperation )
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:
time "#" syntaxOID "#" length "#" data
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].
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.
( 22.214.171.124.126.96.36.199.188.8.131.52 NAME 'pwdHistory' DESC 'The history of user passwords' SYNTAX 184.108.40.206.4.1.14220.127.116.11.40 EQUALITY octetStringMatch NO−USER−MODIFICATION USAGE directoryOperation)
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
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
( 18.104.22.168.22.214.171.124.126.96.36.199 NAME 'pwdGraceUseTime' DESC 'The timestamps of the grace login once the password has expired' SYNTAX 188.8.131.52.4.1.14184.108.40.206.24 EQUALITY generalizedTimeMatch NO−USER−MODIFICATION USAGE directoryOperation)
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.
( 220.127.116.11.18.104.22.168.22.214.171.124 NAME 'pwdReset' DESC 'The indication that the password has been reset' EQUALITY booleanMatch SYNTAX 126.96.36.199.4.1.14188.8.131.52.7 SINGLE−VALUE USAGE directoryOperation)
database bdb suffix dc=example,dc=com ... overlay ppolicy ppolicy_default "cn=Standard,ou=Policies,dc=example,dc=com"
"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".
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.
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. Sermersheim. 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 Software is derived from University of Michigan LDAP 3.3 Release.