LDAP Authentication
LDAP integration is enabled by including the following dependency in the overlay:
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<dependency>
<groupId>org.apereo.cas</groupId>
<artifactId>cas-server-support-ldap</artifactId>
<version>${cas.version}</version>
</dependency>
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implementation "org.apereo.cas:cas-server-support-ldap:${project.'cas.version'}"
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dependencyManagement {
imports {
mavenBom "org.apereo.cas:cas-server-support-bom:${project.'cas.version'}"
}
}
dependencies {
implementation "org.apereo.cas:cas-server-support-ldap"
}
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dependencies {
/*
The following platform references should be included automatically and are listed here for reference only.
implementation enforcedPlatform("org.apereo.cas:cas-server-support-bom:${project.'cas.version'}")
implementation platform(org.springframework.boot.gradle.plugin.SpringBootPlugin.BOM_COORDINATES)
*/
implementation "org.apereo.cas:cas-server-support-ldap"
}
Configuration
CAS authenticates a username/password against an LDAP directory such as Active Directory or OpenLDAP. There are numerous directory architectures and we provide configuration for four common cases.
Note that CAS will automatically create the appropriate components internally based on the settings specified below. If you wish to authenticate against more than one LDAP server, increment the index and specify the settings for the next LDAP server.
Note: Attributes retrieved as part of LDAP authentication are merged with all attributes retrieved from other attribute repository sources, if any. Attributes retrieved directly as part of LDAP authentication trump all other attributes.
The following settings and properties are available from the CAS configuration catalog:
cas.authn.ldap[0].password-encoder.encoding-algorithm=
The encoding algorithm to use such as
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cas.authn.ldap[0].password-encoder.type=NONE
Define the password encoder type to use.
Type may be specified as blank or
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cas.authn.ldap[0].password-policy.groovy.location=
The location of the resource. Resources can be URLS, or files found either on the classpath or outside somewhere in the file system. In the event the configured resource is a Groovy script, specially if the script set to reload on changes, you may need to adjust the total number ofinotify instances.
On Linux, you may need to add the following line to /etc/sysctl.conf :
fs.inotify.max_user_instances = 256 .
You can check the current value via cat /proc/sys/fs/inotify/max_user_instances .
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cas.authn.ldap[0].principal-transformation.groovy.location=
The location of the resource. Resources can be URLS, or files found either on the classpath or outside somewhere in the file system. In the event the configured resource is a Groovy script, specially if the script set to reload on changes, you may need to adjust the total number ofinotify instances.
On Linux, you may need to add the following line to /etc/sysctl.conf :
fs.inotify.max_user_instances = 256 .
You can check the current value via cat /proc/sys/fs/inotify/max_user_instances .
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cas.authn.ldap[0].base-dn=
Base DN to use.
There may be scenarios where different parts of a single LDAP tree could be considered as base-dns. Rather than duplicating
the LDAP configuration block for each individual base-dn, each entry can be specified
and joined together using a special delimiter character. The user DN is retrieved using the combination of all base-dn and DN
resolvers in the order defined. DN resolution should fail if multiple DNs are found. Otherwise the first DN found is returned.
Usual syntax is:
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cas.authn.ldap[0].bind-credential=
The bind credential to use when connecting to LDAP.
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cas.authn.ldap[0].bind-dn=
The bind DN to use when connecting to LDAP. LDAP connection configuration injected into the LDAP connection pool can be initialized with the following parameters:
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cas.authn.ldap[0].ldap-url=
The LDAP url to the server. More than one may be specified, separated by space and/or comma.
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cas.authn.ldap[0].search-filter=
User filter to use for searching.
Syntax is file:/path/to/GroovyScript.groovy
to fully build the final filter template dynamically.
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cas.authn.ldap[0].type=AUTHENTICATED
The authentication type.
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cas.authn.ldap=
Collection of settings related to LDAP authentication. These settings are required to be indexed (i.e. ldap[0].xyz).
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cas.authn.ldap[0].password-encoder.character-encoding=UTF-8
The encoding algorithm to use such as 'UTF-8'.
Relevant when the type used is
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cas.authn.ldap[0].password-encoder.hash-length=16
When used by
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cas.authn.ldap[0].password-encoder.secret=
Secret to use with
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cas.authn.ldap[0].password-encoder.strength=16
Strength or number of iterations to use for password hashing.
Usually relevant when dealing with
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cas.authn.ldap[0].principal-transformation.blocking-pattern=
A regular expression that will be used against the username to match for blocking/forbidden values. If a match is found, an exception will be thrown and principal transformation will fail.
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cas.authn.ldap[0].principal-transformation.case-conversion=NONE
Indicate whether the principal identifier should be transformed into upper-case, lower-case, etc. Available values are as follows:
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cas.authn.ldap[0].principal-transformation.pattern=
A regular expression that will be used against the provided username for username extractions. On a successful match, the first matched group in the pattern will be used as the extracted username.
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cas.authn.ldap[0].principal-transformation.prefix=
Prefix to add to the principal id prior to authentication.
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cas.authn.ldap[0].principal-transformation.suffix=
Suffix to add to the principal id prior to authentication.
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cas.authn.ldap[0].additional-attributes=
List of additional attributes to retrieve, if any.
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cas.authn.ldap[0].allow-missing-principal-attribute-value=true
Flag to indicate whether CAS should block authentication if a specific/configured principal id attribute is not found.
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cas.authn.ldap[0].allow-multiple-dns=
Whether search/query results are allowed to match on multiple DNs, or whether a single unique DN is expected for the result.
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cas.authn.ldap[0].allow-multiple-entries=
Set if multiple Entries are allowed.
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cas.authn.ldap[0].allow-multiple-principal-attribute-values=
Sets a flag that determines whether multiple values are allowed for the
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cas.authn.ldap[0].binary-attributes=
Indicate the collection of attributes that are to be tagged and processed as binary attributes by the underlying search resolver.
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cas.authn.ldap[0].block-wait-time=PT3S
The length of time the pool will block. By default the pool will block indefinitely and there is no guarantee that waiting threads will be serviced in the order in which they made their request. This option should be used with a blocking connection pool when you need to control the exact number of connections that can be created This settings supports the
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cas.authn.ldap[0].collect-dn-attribute=
When entry DN should be called as an attribute and stored into the principal.
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cas.authn.ldap[0].connect-timeout=PT5S
Sets the maximum amount of time that connects will block. This settings supports the
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cas.authn.ldap[0].connection-strategy=
If multiple URLs are provided as the ldapURL this describes how each URL will be processed.
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cas.authn.ldap[0].credential-criteria=
A number of authentication handlers are allowed to determine whether they can operate on the provided credential and as such lend themselves to be tried and tested during the authentication handler selection phase. The credential criteria may be one of the following options:
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cas.authn.ldap[0].deref-aliases=
Define how aliases are de-referenced. Accepted values are:
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cas.authn.ldap[0].disable-pooling=
Whether to use a pooled connection factory in components.
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cas.authn.ldap[0].dn-format=
Specify the dn format accepted by the AD authenticator, etc.
Example format might be
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cas.authn.ldap[0].enhance-with-entry-resolver=true
Whether specific search entry resolvers need to be set on the authenticator, or the default should be used.
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cas.authn.ldap[0].fail-fast=true
Attempt to populate the connection pool early on startup and fail quickly if something goes wrong.
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cas.authn.ldap[0].follow-referrals=true
Set if search referrals should be followed.
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cas.authn.ldap[0].hostname-verifier=DEFAULT
Hostname verification options. Available values are as follows:
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cas.authn.ldap[0].idle-time=PT10M
Removes connections from the pool based on how long they have been idle in the available queue. Prunes connections that have been idle for more than the indicated amount. This settings supports the
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cas.authn.ldap[0].keystore=
Path to the keystore used for SSL connections. Typically contains SSL certificates for the LDAP server. This setting supports the Spring Expression Language.
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cas.authn.ldap[0].keystore-password=
Keystore password. This setting supports the Spring Expression Language.
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cas.authn.ldap[0].keystore-type=
The type of keystore.
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cas.authn.ldap[0].max-pool-size=10
Maximum LDAP connection pool size which the pool can use to grow.
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cas.authn.ldap[0].min-pool-size=3
Minimum LDAP connection pool size. Size the pool should be initialized to and pruned to
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cas.authn.ldap[0].name=
Name of the LDAP handler.
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cas.authn.ldap[0].order=
Order of the authentication handler in the chain.
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cas.authn.ldap[0].page-size=
Request that the server return results in batches of a specific size. See RFC 2696. This control is often used to work around server result size limits. A negative/zero value disables paged requests.
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cas.authn.ldap[0].password-policy.account-state-handling-enabled=true
Indicates whether account state handling should be enabled to process warnings or errors reported back from the authentication response, produced by the source.
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cas.authn.ldap[0].password-policy.custom-policy-class=
An implementation of a policy class that knows how to handle LDAP responses.
The class must be an implementation of
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cas.authn.ldap[0].password-policy.display-warning-on-match=true
Indicates if warning should be displayed, when the ldap attribute value
matches the
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cas.authn.ldap[0].password-policy.enabled=true
Whether password policy should be enabled.
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cas.authn.ldap[0].password-policy.login-failures=5
When dealing with FreeIPA, indicates the number of allows login failures.
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cas.authn.ldap[0].password-policy.password-expiration-number-of-days=180
This is used to calculate an expiration period for the account password.
When defined, LDAP password policy handling will use the
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cas.authn.ldap[0].password-policy.policy-attributes=
Key-value structure (Map) that indicates a list of boolean attributes as keys.
If either attribute value is true, indicating an account state is flagged,
the corresponding error can be thrown.
Example
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cas.authn.ldap[0].password-policy.strategy=DEFAULT
Decide how authentication should handle password policy changes. Available values are as follows:
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cas.authn.ldap[0].password-policy.type=GENERIC
LDAP type.
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cas.authn.ldap[0].password-policy.warn-all=
Always display the password expiration warning regardless.
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cas.authn.ldap[0].password-policy.warning-attribute-name=
Used by an account state handling policy that only calculates account warnings in case the entry carries this attribute.
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cas.authn.ldap[0].password-policy.warning-attribute-value=
Used by an account state handling policy that only calculates account warnings
in case the entry carries an attribute
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cas.authn.ldap[0].password-policy.warning-days=30
This is used to calculate a warning period to see if account expiry is within the calculated window.
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cas.authn.ldap[0].pool-passivator=BIND
You may receive unexpected LDAP failures, when CAS is configured to authenticate
using
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cas.authn.ldap[0].principal-attribute-id=
The attribute to use as the principal identifier built during and upon a successful authentication attempt.
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cas.authn.ldap[0].principal-attribute-list=
List of attributes to retrieve from LDAP.
Attributes can be virtually remapped to multiple names.
Example homePostalAddress:homePostalAddress; .
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cas.authn.ldap[0].principal-attribute-password=
If principalAttributePassword is empty then a user simple bind is done to validate credentials otherwise the given attribute is compared with the given principalAttributePassword using the SHA encrypted value of it. For the anonymous authentication type, if principalAttributePassword is empty then a user simple bind is done to validate credentials otherwise the given attribute is compared with the given principalAttributePassword using the SHA encrypted value of it.
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cas.authn.ldap[0].principal-dn-attribute-name=principalLdapDn
Name of attribute to be used for principal's DN.
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cas.authn.ldap[0].prune-period=PT2H
Removes connections from the pool based on how long they have been idle in the available queue. Run the pruning process at the indicated interval. This settings supports the
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cas.authn.ldap[0].resolve-from-attribute=
If this attribute is set, the value found in the first attribute value will be used in place of the DN.
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cas.authn.ldap[0].response-timeout=PT5S
Duration of time to wait for responses. This settings supports the
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cas.authn.ldap[0].sasl-authorization-id=
SASL authorization id.
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cas.authn.ldap[0].sasl-mechanism=
The SASL mechanism.
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cas.authn.ldap[0].sasl-mutual-auth=
SASL mutual auth is enabled?
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cas.authn.ldap[0].sasl-quality-of-protection=
SASL quality of protected.
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cas.authn.ldap[0].sasl-realm=
The SASL realm.
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cas.authn.ldap[0].sasl-security-strength=
SASL security strength.
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cas.authn.ldap[0].search-entry-handlers.case-change.attribute-name-case-change=
The Attribute name case change.
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cas.authn.ldap[0].search-entry-handlers.case-change.attribute-names=
The Attribute names.
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cas.authn.ldap[0].search-entry-handlers.case-change.attribute-value-case-change=
The Attribute value case change.
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cas.authn.ldap[0].search-entry-handlers.case-change.dn-case-change=
The Dn case change.
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cas.authn.ldap[0].search-entry-handlers.dn-attribute.add-if-exists=
The Add if exists.
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cas.authn.ldap[0].search-entry-handlers.dn-attribute.dn-attribute-name=entryDN
The Dn attribute name.
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cas.authn.ldap[0].search-entry-handlers.merge-attribute.attribute-names=
The Attribute names.
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cas.authn.ldap[0].search-entry-handlers.merge-attribute.merge-attribute-name=
The Merge attribute name.
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cas.authn.ldap[0].search-entry-handlers.primary-group-id.base-dn=
The Base dn.
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cas.authn.ldap[0].search-entry-handlers.primary-group-id.group-filter=(&(objectClass=group)(objectSid={0}))
The Group filter.
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cas.authn.ldap[0].search-entry-handlers.recursive.merge-attributes=
The Merge attributes.
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cas.authn.ldap[0].search-entry-handlers.recursive.search-attribute=
The Search attribute.
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cas.authn.ldap[0].search-entry-handlers.search-referral.limit=10
The default referral limit.
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cas.authn.ldap[0].search-entry-handlers.search-result.limit=10
The default referral limit.
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cas.authn.ldap[0].search-entry-handlers.type=
The type of search entry handler to choose. Available values are as follows:
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cas.authn.ldap[0].state=ACTIVE
Define the scope and state of this authentication handler and the lifecycle in which it can be invoked or activated.
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cas.authn.ldap[0].subtree-search=true
Whether subtree searching is allowed.
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cas.authn.ldap[0].trust-certificates=
Path of the trust certificates to use for the SSL connection. Ignores keystore-related settings when activated and used.
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cas.authn.ldap[0].trust-manager=
Trust Manager options. Trust managers are responsible for managing the trust material that is used when making LDAP trust decisions, and for deciding whether credentials presented by a peer should be accepted. Accepted values are: *
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cas.authn.ldap[0].trust-store=
Path to the keystore used to determine which certificates or certificate authorities should be trusted. Used when connecting to an LDAP server via LDAPS or startTLS connection. If left blank, the default truststore for the Java runtime is used. This setting supports the Spring Expression Language.
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cas.authn.ldap[0].trust-store-password=
Password needed to open the truststore. This setting supports the Spring Expression Language.
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cas.authn.ldap[0].trust-store-type=
The type of trust keystore that determines which certificates or certificate authorities are trusted.
Types depend on underlying java platform, typically
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cas.authn.ldap[0].use-start-tls=
Whether TLS should be used and enabled when establishing the connection.
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cas.authn.ldap[0].validate-on-checkout=true
Whether connections should be validated when loaned out from the pool.
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cas.authn.ldap[0].validate-period=PT5M
Period at which pool should be validated. This settings supports the
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cas.authn.ldap[0].validate-periodically=true
Whether connections should be validated periodically when the pool is idle.
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cas.authn.ldap[0].validate-timeout=PT5S
Period at which validation operations may time out. This settings supports the
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cas.authn.ldap[0].validator.attribute-name=objectClass
Attribute name to use for the compare validator.
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cas.authn.ldap[0].validator.attribute-value=top
Attribute values to use for the compare validator.
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cas.authn.ldap[0].validator.base-dn=EMPTY
Base DN to use for the search request of the search validator.
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cas.authn.ldap[0].validator.dn=EMPTY
DN to compare to use for the compare validator.
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cas.authn.ldap[0].validator.scope=OBJECT
Search scope to use for the search request of the search validator.
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cas.authn.ldap[0].validator.search-filter=(objectClass=*)
Search filter to use for the search request of the search validator.
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cas.authn.ldap[0].validator.type=search
Determine the LDAP validator type. The following LDAP validators can be used to test connection health status:
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LDAP Scriptable Search Filter
LDAP search filters can point to an external Groovy script to dynamically construct the final filter template.
The script itself may be designed as:
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import org.ldaptive.*
import org.springframework.context.*
def run(Object[] args) {
def filter = (FilterTemplate) args[0]
def parameters = (Map) args[1]
def applicationContext = (ApplicationContext) args[2]
def logger = args[3]
logger.info("Configuring LDAP filter")
filter.setFilter("uid=something")
}
The following parameters are passed to the script:
Parameter | Description |
---|---|
filter |
FilterTemplate to be updated by the script and used for the LDAP query. |
parameters |
Map of query parameters which may be used to construct the final filter. |
applicationContext |
Reference to the Spring ApplicationContext reference. |
logger |
The object responsible for issuing log messages such as logger.info(...) . |
If you need to design your own password encoding scheme where the type is specified as a fully qualified Java class name, the structure of the class would be similar to the following:
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package org.example.cas;
import org.springframework.security.crypto.codec.*;
import org.springframework.security.crypto.password.*;
public class MyEncoder extends AbstractPasswordEncoder {
@Override
protected byte[] encode(CharSequence rawPassword, byte[] salt) {
return ...
}
}
If you need to design your own password encoding scheme where the type is specified as a path to a Groovy script, the structure of the script would be similar to the following:
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import java.util.*
byte[] run(final Object... args) {
def rawPassword = args[0]
def generatedSalt = args[1]
def logger = args[2]
def casApplicationContext = args[3]
logger.debug("Encoding password...")
return ...
}
Boolean matches(final Object... args) {
def rawPassword = args[0]
def encodedPassword = args[1]
def logger = args[2]
def casApplicationContext = args[3]
logger.debug("Does match or not ?");
return ...
Password Policy Strategies
If the password policy strategy is to be handed off to a Groovy script, the outline of the script may be as follows:
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import java.util.*
import org.ldaptive.auth.*
import org.apereo.cas.*
import org.apereo.cas.authentication.*
import org.apereo.cas.authentication.support.*
List<MessageDescriptor> run(final Object... args) {
def response = args[0]
def configuration = args[1];
def logger = args[2]
def applicationContext = args[3]
logger.info("Handling password policy [{}] via ${configuration.getAccountStateHandler()}", response)
def accountStateHandler = configuration.getAccountStateHandler()
return accountStateHandler.handle(response, configuration)
}
The parameters passed are as follows:
Parameter | Description |
---|---|
response |
The LDAP authentication response of type org.ldaptive.auth.AuthenticationResponse |
configuration |
The LDAP password policy configuration carrying the account state handler defined. |
logger |
The object responsible for issuing log messages such as logger.info(...) . |
Authentication handlers that generally deal with username-password credentials can be configured to transform the user id prior to executing the authentication sequence. Each authentication strategy in CAS provides settings to properly transform the principal. Refer to the relevant settings for the authentication strategy at hand to learn more.
Authentication handlers as part of principal transformation may also be provided a path to a Groovy script to transform the provided username. The outline of the script may take on the following form:
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String run(final Object... args) {
def providedUsername = args[0]
def logger = args[1]
return providedUsername.concat("SomethingElse")
}
Certain authentication handlers are allowed to determine whether they can operate on the provided credential and as such lend themselves to be tried and tested during the authentication handler selection phase. The credential criteria may be one of the following options:
- A regular expression pattern that is tested against the credential identifier.
- A fully qualified class name of your own design that looks similar to the below example:
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import java.util.function.Predicate;
import org.apereo.cas.authentication.Credential;
public class PredicateExample implements Predicate<Credential> {
@Override
public boolean test(final Credential credential) {
// Examine the credential and return true/false
}
}
- Path to an external Groovy script that looks similar to the below example:
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import org.apereo.cas.authentication.Credential
import java.util.function.Predicate
class PredicateExample implements Predicate<Credential> {
@Override
boolean test(final Credential credential) {
// test and return result
}
}
Configuration Metadata
The collection of configuration properties listed in this section are automatically generated from the CAS source and components that contain the actual field definitions, types, descriptions, modules, etc. This metadata may not always be 100% accurate, or could be lacking details and sufficient explanations.
Be Selective
This section is meant as a guide only. Do NOT copy/paste the entire collection of settings into your CAS configuration; rather pick only the properties that you need. Do NOT enable settings unless you are certain of their purpose and do NOT copy settings into your configuration only to keep them as reference. All these ideas lead to upgrade headaches, maintenance nightmares and premature aging.
YAGNI
Note that for nearly ALL use cases, declaring and configuring properties listed here is sufficient. You should NOT have to explicitly massage a CAS XML/Java/etc configuration file to design an authentication handler, create attribute release policies, etc. CAS at runtime will auto-configure all required changes for you. If you are unsure about the meaning of a given CAS setting, do NOT turn it on without hesitation. Review the codebase or better yet, ask questions to clarify the intended behavior.
Naming Convention
Property names can be specified in very relaxed terms. For instance cas.someProperty
, cas.some-property
, cas.some_property
are all valid names. While all
forms are accepted by CAS, there are certain components (in CAS and other frameworks used) whose activation at runtime is conditional on a property value, where
this property is required to have been specified in CAS configuration using kebab case. This is both true for properties that are owned by CAS as well as those
that might be presented to the system via an external library or framework such as Spring Boot, etc.
When possible, properties should be stored in lower-case kebab format, such as cas.property-name=value
.
The only possible exception to this rule is when naming actuator endpoints; The name of the
actuator endpoints (i.e. ssoSessions
) MUST remain in camelCase mode.
Settings and properties that are controlled by the CAS platform directly always begin with the prefix cas
. All other settings are controlled and provided
to CAS via other underlying frameworks and may have their own schemas and syntax. BE CAREFUL with
the distinction. Unrecognized properties are rejected by CAS and/or frameworks upon which CAS depends. This means if you somehow misspell a property definition
or fail to adhere to the dot-notation syntax and such, your setting is entirely refused by CAS and likely the feature it controls will never be activated in the
way you intend.
Validation
Configuration properties are automatically validated on CAS startup to report issues with configuration binding, specially if defined CAS settings cannot be
recognized or validated by the configuration schema. The validation process is on by default and can be skipped on startup using a special system
property SKIP_CONFIG_VALIDATION
that should be set to true
. Additional validation processes are also handled
via Configuration Metadata and property migrations applied automatically on
startup by Spring Boot and family.
Indexed Settings
CAS settings able to accept multiple values are typically documented with an index, such as cas.some.setting[0]=value
. The index [0]
is meant to be
incremented by the adopter to allow for distinct multiple configuration blocks.
Password Policy Enforcement
To learn how to enforce a password policy for LDAP, please review this guide.
Troubleshooting
To enable additional logging, modify the logging configuration file to add the following:
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<Logger name="org.ldaptive" level="debug" additivity="false">
<AppenderRef ref="console"/>
<AppenderRef ref="file"/>
</Logger>