Configuring LDAP

This topic includes descriptions of the LDAP configuration options available for configuring group-based authorization.

Configuring LDAP Context

All standard Java LDAP configurations are supported. Broker configurations starting with ldap.java.naming and ldap.com.sun.jndi are stripped of their ldap. prefix and these standard Java LDAP configurations are used to make connections to the LDAP server. You must configure ldap.java.naming.provider.url with the URL of your LDAP server. For example:

ldap.java.naming.provider.url=ldap://somehost:389

For a complete list of standard Java configurations for the LDAP naming service provider and Java Naming and Directory Interface (JNDI), see LDAP Naming Service Provider for the Java Naming and Directory Interface (JNDI).

Note

Be aware that nested LDAP groups are not supported.

Configuring SSL for LDAP

Enable SSL for the connections from the Confluent Server Authorizer to your LDAP server by setting ldap.java.naming.security.protocol=SSL. LDAP provider URL must use the protocol ldaps if SSL is enabled. All the SSL configuration options of Kafka clients are supported and must be prefixed with ldap.. For example:

# Configure provider URL with `ldaps` as protocol
ldap.java.naming.provider.url=ldaps://somehost:389
# Enable SSL for connections to LDAP server
ldap.java.naming.security.protocol=SSL
# Path of truststore for connections to LDAP
ldap.ssl.truststore.location=/path/to/truststore.jks
# Password of LDAP truststore
ldap.ssl.truststore.password=truststore-secret

For a list of supported SSL configurations, see Encryption and Authentication with SSL.

Note

In Java 8 update 181 and later, host name verification is enabled by default on LDAPS connections. You can disable this verification by setting KAFKA_OPTS=-Dcom.sun.jndi.ldap.object.disableEndpointIdentification=true, but you should avoid using this option in production systems. Prior to Java 8 update 181, host name verification was disabled by default for LDAPS connections. For improved security, consider upgrading to Java 8 181 or later.

Configuring GSSAPI for LDAP

You can use GSSAPI to authenticate the Confluent Server Authorizer with your LDAP server if Kerberos is enabled on your LDAP server. You can configure the JAAS configuration for GSSAPI using the ldap.sasl.jaas.config configuration option. You must also configure the authentication protocol and security principal using standard Java LDAP configurations prefixed with ldap.. For example:

# Configure SASL/GSSAPI as the authentication protocol for LDAP context.
ldap.java.naming.security.authentication=GSSAPI
# Security principal for LDAP context
ldap.java.naming.security.principal=ldap@EXAMPLE.COM
# JAAS configuration for Kerberos authentication with LDAP server
ldap.sasl.jaas.config=com.sun.security.auth.module.Krb5LoginModule required \
  keyTab="/tmp/keytabs/ldap.keytab" \
  principal="ldap@EXAMPLE.COM" \
  storeKey="true" \
  useKeyTab="true";

Note

The keytab is a local file that stores the principal for LDAP, as well as a timestamp, a key version number, and the encrypted keys. In this context, keyTab is used to authenticate Kerberos with the LDAP server without having to explicitly enter a password. You can view the principal in the keytab using the klist command:

klist -kt /tmp/keytabs/ldap.keytab

#keytab content for LDAP principal
KVNO Timestamp         Principal
---- ----------------- ------------------------------------
   1 12/31/21 17:00:00 host/ldap@EXAMPLE.COM

If ldap.sasl.jaas.config is not configured, then the default JAAS configuration of the broker will be used. The default JAAS configuration (the value specified in the system property java.security.auth.login.config) is loaded from the login context KafkaServer that is used as the broker’s login context using a single shared login. You should use this configuration option for LDAP only if the principal in this context can be used to search LDAP.

To test and perform basic troubleshooting on your LDAP client configuration when configuring Kafka to authenticate to LDAP using Kerberos, refer to Testing and Troubleshooting LDAP Client Authentication.

Configuring Password Credentials for LDAP

If password authentication is enabled on your LDAP server, then you can configure the user principal and password so that brokers can authenticate with the LDAP server using simple authentication. Use standard Java configurations prefixed with ldap. to configure LDAP credentials for the broker. For example:

# Specify the LDAP security authentication protocol
ldap.java.naming.security.authentication=SIMPLE
# Identify the principal for the LDAP context
ldap.java.naming.security.principal=CN=Kafka Broker,OU=Users,DC=EXAMPLE,DC=COM
# Security credential is the password of the user that performs LDAP search
ldap.java.naming.security.credentials=broker-secret

Configuring LDAP Filters to Limit Search Results

If you have a large number of users in the LDAP server, it is likely that only a subset require access to Confluent Platform. In such instances, you can configure filters to reduce the size of search results because brokers only require group mapping for the small subset of users who connect to the Confluent Platform. LDAP filters are particularly useful for user mode searches where you wish to avoid having brokers process every user defined in the LDAP server.

You can configure a simple filter by adding all users accessing Confluent Platform to a group. For example, the following configuration filters out users belonging to the Kafka group:

ldap.user.search.filter=(memberOf=CN=Kafka,CN=Users,DC=EXAMPLE,DC=COM)

You can also configure a simple filter that processes users belonging to a set of groups when the users of the Confluent Platform already belong to a small set of groups. For example, the following filter processes users belonging to the groups Administrators and Kafka Developers:

ldap.user.search.filter=(|(memberOf=CN=Administrators,CN=Users,DC=EXAMPLE,DC=COM)(memberOf=CN=Kafka Developers,CN=Users,DC=example,DC=com))

If your LDAP server already has other attributes that match users or groups connecting to Confluent Platform, you can filter based on those. You can use any valid LDAP search filter to limit search results in both user and group search modes.

LDAP search filters do not use regex. Instead, LDAP search filters support 'substring' searches (which are not the same as wildcards)–not Regular Expressions, which run on the LDAP server side rather than Confluent Platform. Examples of valid substring LDAP search filters are: '(uid=abc*)', and '(mail=`john@*.com')`)'.

When specifying memberOf and distinguishedName, you must specify the full DN (distinguished name) of the objects. For details about how to specify the full DN when setting LDAP search filters while using Active Directory, refer to Active Directory: LDAP Syntax Filters.

LDAP Configuration Reference

Confluent License

confluent.license

Confluent issues a license key to each subscriber. The license key is a short snippet of text that you can copy and paste. Without the license key, you can use Confluent security plugins for a 30-day trial period. If you are a subscriber and don’t have a license key, please contact Confluent Support at support@confluent.io.

  • Type: string
  • Default: “”
  • Importance: high

LDAP Search Configuration

ldap.principal.mapping

LDAP principal mapping mode dictates the mechanism used to determine the LDAP user principal name for downstream authorization purposes.

  • Type: string
  • Default: default
  • Valid Values: [default, ldap]
  • Importance: medium

Mapping mode options:

  • default - Use the case-sensitive authentication username supplied by the

    user/caller as the user principal for authorization. This is the default value.

  • ldap - Use the case-sensitive user principal name from the LDAP server as the user principal for authorization. Note that even though the user principal name lookup is case-insensitive, the case from the LDAP records is used rather than the case used in the original authenticated username.

    Example: If a user principal in LDAP is all-caps “BOB”, the user can sign in with “bob” and during LDAP authentication, the lookup finds “BOB” and sets “BOB” as the user principal for authorization purposes.

Important

When the mapping mode is set to ldap, the user principal value specified in the Kafka cluster role bindings must match the case of the user principal name used in the LDAP records; otherwise, authorization fails.

ldap.refresh.interval.ms

LDAP group cache refresh interval in milliseconds. If set to zero, then persistent LDAP search is used.

  • Type: int
  • Default: 60000
  • Importance: medium
ldap.search.page.size

Page size for LDAP search if persistent search is disabled (in other words, when the refresh interval is greater than zero). Paging is disabled by default.

  • Type: int
  • Default: 0
  • Importance: medium
ldap.search.mode

LDAP search mode that indicates if the user-to-group mapping is retrieved by searching for group or user entries. Valid values are USERS and GROUPS.

  • Type: string
  • Default: GROUPS
  • Valid Values: [GROUPS, USERS]
  • Importance: medium

LDAP search by groups

ldap.group.search.base

LDAP search base for group-based search.

  • Type: string
  • Default: ou=groups
  • Importance: high
ldap.group.search.filter

LDAP search filter for group-based search.

  • Type: string
  • Default: “”
  • Importance: medium
ldap.group.search.scope

LDAP search scope for group-based search. Valid values are 0 (OBJECT), 1 (ONELEVEL) and 2 (SUBTREE).

  • Type: int
  • Default: 1
  • Importance: medium
ldap.group.object.class

LDAP object class for groups.

  • Type: string
  • Default: groupOfNames
  • Importance: medium
ldap.group.name.attribute

Name of attribute that contains the name of the group in a group entry obtained using an LDAP search. A regex pattern may be specified to extract the group name used in ACLs from this attribute by configuring ldap.group.name.attribute.pattern.

  • Type: string
  • Default: cn
  • Importance: high
ldap.group.name.attribute.pattern

A Java regular expression pattern that extracts the group name used in ACLs from the name of the group obtained from the LDAP attribute specified using ldap.group.name.attribute. By default the full value of the attribute is used.

  • Type: string
  • Default: “”
  • Importance: low
ldap.group.member.attribute

The name of the attribute that contains the members of the group in a group entry obtained using an LDAP search. A regex pattern may be specified to extract the user principals from this attribute by configuring ldap.group.member.attribute.pattern.

  • Type: string
  • Default: member
  • Importance: high
ldap.group.member.attribute.pattern

A Java regular expression pattern that extracts the user principals of group members from group member entries obtained from the LDAP attribute specified using ldap.group.member.attribute. By default the full value of the attribute is used.

  • Type: string
  • Default: “”
  • Importance: medium
ldap.group.dn.name.pattern

A Java regular expression pattern that extracts the group name from the distinguished name (DN) of the group when a group is renamed. This is used only when persistent search is enabled. By default the ldap.group.name.attribute is extracted from the DN.

  • Type: string
  • Default: “”
  • Importance: low
ldap.user.dn.name.pattern

A Java regular expression pattern used to extract user name from the distinguished name (DN) of the user when user is renamed. This is used only when persistent search is enabled. By default ldap.user.name.attribute is extracted from the DN.

  • Type: string
  • Default: “”
  • Importance: low

LDAP search by users

ldap.user.search.base

The LDAP search base for a user-based search.

  • Type: string
  • Default: ou=users
  • Importance: medium
ldap.user.search.filter

The LDAP search filter for a user-based search.

  • Type: string
  • Default: “”
  • Importance: medium
ldap.user.search.scope

The LDAP search scope for a user-based search. Valid values are 0 (OBJECT), 1 (ONELEVEL), and 2 (SUBTREE).

  • Type: int
  • Default: 1
  • Importance: medium
ldap.user.object.class

The LDAP object class for users.

  • Type: string
  • Default: person
  • Importance: medium
ldap.user.name.attribute

Name of attribute that contains the user principal in a user entry obtained using an LDAP search. A regex pattern may be specified to extract the user principal from this attribute by configuring ldap.user.name.attribute.pattern.

  • Type: string
  • Default: uid
  • Importance: medium
ldap.user.name.attribute.pattern

A Java regular expression pattern used to extract the user principal from the name of the user obtained from the LDAP attribute specified using ldap.user.name.attribute. By default the full value of the attribute is used.

  • Type: string
  • Default: “”
  • Importance: medium
ldap.user.memberof.attribute

The name of the attribute that contains the groups in a user entry obtained using an LDAP search. A regex pattern may be specified to extract the group names used in ACLs from this attribute by configuring ldap.user.memberof.attribute.pattern.

  • Type: string
  • Default: memberof
  • Importance: medium
ldap.user.memberof.attribute.pattern

A Java regular expression pattern used to extract the names of groups from user entries obtained from the LDAP attribute specified using ldap.user.memberof.attribute. By default the full value of the attribute is used.

  • Type: string
  • Default: “”
  • Importance: medium

Error Handling Configuration

ldap.retry.backoff.ms

Initial retry backoff in milliseconds. Exponential backoff is used if ldap.retry.backoff.max.ms is set to a higher value.

  • Type: int
  • Default: 100
  • Importance: medium
ldap.retry.backoff.max.ms

Maximum retry backoff in milliseconds. Exponential backoff is used if ldap.retry.backoff.ms is set to a lower value.

  • Type: int
  • Default: 1000
  • Importance: medium
ldap.retry.timeout.ms

Timeout for LDAP search retries after which the Confluent Server Authorizer is marked as failed. All requests are denied access if a successful cache refresh cannot be performed within this time.

  • Type: long
  • Default: 86400000
  • Importance: medium

SSL Configuration for LDAP connection

ldap.ssl.protocol

The SSL protocol used to generate the SSLContext. The default setting is TLS, which is fine for most cases. Allowed values in recent JVMs are TLS, TLSv1.1, and TLSv1.2. SSL, SSLv2, and SSLv3 may be supported in older JVMs, but their usage is discouraged due to known security vulnerabilities.

  • Type: string
  • Default: TLS
  • Importance: medium
ldap.ssl.provider

The name of the security provider used for SSL connections. The default value is the default security provider of the JVM.

  • Type: string
  • Default: null
  • Importance: medium
ldap.ssl.enabled.protocols

The list of protocols enabled for SSL connections.

  • Type: list
  • Default: TLSv1.2,TLSv1.1,TLSv1
  • Importance: medium
ldap.ssl.keystore.type

The file format of the key store file. This attribute is optional for the client.

  • Type: string
  • Default: JKS
  • Importance: medium
ldap.ssl.truststore.type

The file format of the trust store file.

  • Type: string
  • Default: JKS
  • Importance: medium
ldap.ssl.key.password

The password of the private key in the key store file. This attribute is optional for client.

  • Type: password
  • Default: null
  • Importance: high
ldap.ssl.keystore.location

The location of the key store file. This attribute is optional for the client and can be used for two-way authentication for client.

  • Type: string
  • Default: null
  • Importance: high
ldap.ssl.keystore.password

The store password for the key store file. This attribute is optional for the client and is only needed if ssl.keystore.location is configured.

  • Type: password
  • Default: null
  • Importance: high
ldap.ssl.truststore.location

The location of the trust store file.

  • Type: string
  • Default: null
  • Importance: high
ldap.ssl.truststore.password

The password for the trust store file. If a password is not set, then access to the truststore is still available, but integrity checking is disabled.

  • Type: password
  • Default: null
  • Importance: high
ldap.ssl.cipher.suites

A list of cipher suites. This is a named combination of authentication, encryption, MAC and key exchange algorithm used to negotiate the security settings for a network connection using TLS or SSL network protocol. By default all the available cipher suites are supported.

  • Type: list
  • Default: null
  • Importance: low
ldap.ssl.keymanager.algorithm

The algorithm used by the key manager factory for SSL connections. The default value is the key manager factory algorithm configured for the Java Virtual Machine.

  • Type: string
  • Default: SunX509
  • Importance: low
ldap.ssl.secure.random.implementation

The SecureRandom PRNG implementation to use for SSL cryptography operations.

  • Type: string
  • Default: null
  • Importance: low
ldap.ssl.trustmanager.algorithm

The algorithm used by trust manager factory for SSL connections. The default value is the trust manager factory algorithm configured for the Java Virtual Machine.

  • Type: string
  • Default: PKIX
  • Importance: low

SASL Configuration for LDAP connection

ldap.sasl.jaas.config

JAAS login context parameters for SASL connections in the format used by JAAS configuration files. JAAS configuration file format is described in the JAAS Login Configuration File documentation. The format for the value is: loginModuleClass controlFlag (optionName=optionValue)*;.

  • Type: password
  • Default: null
  • Importance: medium
ldap.sasl.login.callback.handler.class

The fully qualified name of a SASL login callback handler class that implements the AuthenticateCallbackHandler interface.

  • Type: class
  • Default: null
  • Importance: medium
ldap.sasl.login.class

The fully qualified name of a class that implements the Login interface.

  • Type: class
  • Default: null
  • Importance: medium
ldap.sasl.kerberos.kinit.cmd

The Kerberos kinit command path.

  • Type: string
  • Default: /usr/bin/kinit
  • Importance: low
ldap.sasl.kerberos.min.time.before.relogin

The login thread sleep time between refresh attempts.

  • Type: long
  • Default: 60000
  • Importance: low
ldap.sasl.kerberos.ticket.renew.jitter

Percentage of random jitter added to the renewal time.

  • Type: double
  • Default: 0.05
  • Importance: low
ldap.sasl.kerberos.ticket.renew.window.factor

The duration that the login thread will sleep until the specified window factor of time from last refresh to ticket’s expiry has been reached, at which time it will try to renew the ticket.

  • Type: double
  • Default: 0.8
  • Importance: low