Configure LDAP Group-Based Authorization for MDS

Important

The user ID specified in group role bindings is case-specific, and must match the case specified in the AD record. Also note that when logging in as a super user, the login ID is also case-specific and must match the case specified for the user ID in role bindings.

Configure 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

Following are detailed descriptions of the required baseline JNDI LDAP configuration options that Kafka uses to authenticate to the directory service with the bind user.

ldap.java.naming.provider.url
This option defines the URL to use for connections to the LDAP server. The default hostname is localhost; the default port is 389. You must specify this option for the MDS configuration. To configure with multiple LDAP servers for high availability, you can also supply space-separated list of LDAP URLs.
ldap.java.naming.security.authentication
If password authentication is enabled on your LDAP server, you can configure the user principal and password so that brokers can authenticate with the LDAP server using simple authentication. If you do not want to authenticate with the LDAP server, specify none. The recommended value to get your MDS up and running is simple, which is a PLAINTEXT authentication protocol and provides no security. For production instances, you should specify a more secure SASL method supported by your LDAP server (such as SASL_GSSAPI).
ldap.java.naming.security.credentials
Specifies the security credentials (password) of the principal performing the LDAP search.
ldap.java.naming.security.principal
Specifies the security principal, which is the distinguished name of the LDAP user performing the LDAP search. In this configuration, specify the MDS user using the DN (LDAP distinguished name, which is a sequence of relative distinguished names (RDN) connected by commas).

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).

Configure multiple LDAP servers

Confluent Platform supports configuring MDS with multiple LDAP servers from version 7.7 and later. Instead of just one URL, you can also supply a space-separated list of LDAP URLs. In this case, the LDAP provider attempts to use each URL in turn until it is able to create a successful connection. This is useful for achieving high availability of LDAP service in Confluent Platform. For example:

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

Configure TLS for LDAP

Enable TLS for the connections from the LDAP Authorizer to your LDAP server by setting ldap.java.naming.security.protocol=SSL. LDAP provider URL must use the protocol ldaps if TLS is enabled. All the TLS 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 TLS/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 TLS configurations, see Use TLS Authentication in Confluent Platform.

Configure GSSAPI for LDAP

You can use GSSAPI to authenticate the LDAP Authorizer with your LDAP server if Kerberos is enabled on your LDAP server. The JAAS configuration for GSSAPI may be configured using the configuration option ldap.sasl.jaas.config. Authentication protocol and security principal must also be configured using standard Java LDAP configs 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";

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

Configure 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:

# Configure simple LDAP binding for authentication
ldap.java.naming.security.authentication=SIMPLE
# Security principal is the distinguished name of the LDAP user that performs LDAP search
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

Configure 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.

Important

Most LDAP clients, by default, limit the number of users returned in an LDAP group to 1500 (this limit can vary between LDAP clients and servers). If you have more than 1500 users in an LDAP group, you can configure filters that limit the search results for users in the group, which can be an effective way to work within or around size limits.

Also, check the documentation for your LDAP client or server to determine the default limit for users returned in a group (and any configurable limits) and to configure filters for your environment.

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 Authorizer Configuration Options

LDAP Search Configuration

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 LDAP 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

TLS Configuration for LDAP connection

ldap.ssl.protocol

The TLS protocol used to generate the SSLContext. The default is TLSv1.3 when running with Java 11 or newer, TLSv1.2 otherwise. This value should be fine for most use cases. Allowed values in recent JVMs are TLSv1.2 and TLSv1.3. TLS, TLSv1.1, SSL, SSLv2 and SSLv3 might be supported in older JVMs, but their usage is discouraged due to known security vulnerabilities. With the default value for this configuration and ssl.enabled.protocols, clients downgrade to TLSv1.2 if the server does not support TLSv1.3. If this configuration is set to TLSv1.2, clients do not use TLSv1.3, even if it is one of the values in ssl.enabled.protocols and the server only supports TLSv1.3.

  • Type: string
  • Default: TLSv1.3
  • Importance: medium
ldap.ssl.provider

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

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

The comma-separated list of protocols enabled for TLS connections. The default value is TLSv1.2,TLSv1.3 when running with Java 11 or later, TLSv1.2 otherwise. With the default value for Java 11 (TLSv1.2,TLSv1.3), Kafka clients and brokers prefer TLSv1.3 if both support it, and falls back to TLSv1.2 otherwise (assuming both support at least TLSv1.2).

  • Type: list
  • Default: TLSv1.2,TLSv1.3
  • 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 client authentication.

  • 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. 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 TLS 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 TLS cryptography operations.

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

The algorithm used by trust manager factory for TLS 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