Configuration Overview
The broker configuration (in the server.properties
file) must set authorizer.class.name
to
io.confluent.kafka.security.ldap.authorizer.LdapAuthorizer
to enable LDAP group-based authorization.
authorizer.class.name=io.confluent.kafka.security.ldap.authorizer.LdapAuthorizer
authorizer.class.name
Fully qualified class name of the Apache Kafka® broker authorizer implementation class that implements
the kafka.security.auth.Authorizer
interface.
- Type: class
- Default: “”
- Importance: low
The following configuration options of SimpleAclAuthorizer
are also processed by the LDAP Authorizer.
super.users
Semicolon-separated list of principals of super users or super groups who are allowed access to all of the resources
for all of the actions for all of the hosts. If a resource has no ACLs associated with it, then only super users can
access the resource. For an example of how to set this, see Configure Brokers.
- Type: string
- Default: “”
- Importance: medium
allow.everyone.if.no.acl.found
Boolean flag that indicates if everyone is allowed access to a resource if no ACL is found for the user principal
or any of the groups that the user belongs to.
- Type: boolean
- Default: false
- Importance: medium
Note
To enable the LDAP Authorizer to obtain the user principal to group mappings from your
LDAP server, configure these options to match the settings on your LDAP server.
In 5.3.0 and later, when using the LDAP Authorizer, you can use either the
ldap.
or ldap.authorizer.
prefix (ldap.authorizer.
is supported for backward compatibility).
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 can also use the prefix ldap.authorizer.
. 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 LDAP 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.
or ldap.authorizer.
.
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 LDAP Authorizer with your LDAP server if Kerberos
is enabled on your LDAP server. The JAAS configuration for GSSAPI may be configured using
the config option ldap.sasl.jaas.config
. Authentication protocol and security
principal must also be configured using standard Java LDAP configs prefixed with ldap.
or ldap.authorizer.
.
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.
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.
or ldap.authorizer.
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 Search
To perform group-based authorization, brokers require a mapping of
the user principal. This mapping is determined during authentication
to group principals that define access rules.
You can configure broker search parameters so that your
LDAP server derives group principals for every user that connects to Confluent Platform.
The mapping can be derived from either user entries or group entries in LDAP by
configuring the search mode to use either USERS
or GROUPS
. You must
configure the search mode based on which entry contains both user and group
principals in the format used for authentication and authorization. You can
configure the LDAP attributes containing user and group principals in your LDAP
server entries, and regular expression patterns to extract the principal
from these attributes.
Sample Configuration for Group-Based Search
By default, brokers read group entries from LDAP using group-based mode. If the
LDAP group entries in your LDAP server contain the user principal of members in
the format used to authenticate the principal by Kafka brokers, then you can use the
default group search.
For example, consider an LDAP server with a group entry that contains the following attributes:
dn: CN=Kafka Developers,OU=Groups,DC=EXAMPLE,DC=COM
cn: kafkadev
objectClass: groupOfNames
member: UID=alice,OU=Users,DC=EXAMPLE,DC=COM
member: UID=bob,OU=Users,DC=EXAMPLE,DC=COM
If the user principals used by Kafka are User:alice
and User:bob
, then you
can configure the group-based search to map User:alice
and User:bob
to the group
principal Group:kafkadev
using the following configuration:
ldap.search.mode=GROUPS
ldap.group.search.base=DC=EXAMPLE,DC=COM
ldap.group.object.class=groupOfNames
ldap.group.name.attribute=cn
ldap.group.member.attribute=member
ldap.group.member.attribute.pattern=UID=(.*),OU=Users,DC=EXAMPLE,DC=COM
In some environments, the distinguished name (DN) of the user in the member entry may
not contain the principal generated by Kafka brokers during authentication. In
these cases, you can configure user-based search as described in Sample Configuration for User-Based Search.
Sample Configuration for User-Based Search
The user principal used for authorization by brokers is the principal generated during
authentication. For example, with Kerberos authentication using GSSAPI, the
default principal is the short name from the Kerberos principal. In some LDAP
environments, this principal may not appear in the member
attribute of group
entries. In such cases, you can search in user mode to extract the principal
and group principals from LDAP user entries. This search mode provides the
flexibility required for most LDAP environments because group principals are
easily adapted to the format used in the user entry of your LDAP server.
For example, consider an LDAP server with a user entry containing the following
attributes:
objectClass: user
distinguishedName: CN=Joe Bloggs,CN=Users,DC=EXAMPLE,DC=COM
sAMAccountName: joe
memberOf: CN=Kafka Developers,CN=Users,DC=EXAMPLE,DC=COM
If the user principal used by Kafka is User:joe
, then you can configure
group-based search to map User:joe
to the group Group:Kafka Developers
using the following configuration:
ldap.search.mode=USERS
ldap.user.search.base=DC=EXAMPLE,DC=COM
ldap.user.object.class=user
ldap.user.name.attribute=sAMAccountName
ldap.user.memberof.attribute=memberOf
ldap.user.memberof.attribute.pattern=CN=(.*),CN=Users,.*
For LDAP servers with a large number of users where only a small subset access
Kafka, you can configure filters to limit the size of search results as described
in Configuring LDAP Filters to Limit Search Results.
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.
Using Persistent LDAP Search
By default, the mapping of users to groups obtained from LDAP is refreshed periodically
with a refresh interval that you can configure using ldap.refresh.interval.ms
.
If your LDAP server supports persistent search, you can set the refresh interval to zero
to initiate a persistent LDAP search in the LDAP Authorizer. LDAP updates are processed
as soon as notifications are received, enabling any changes to be used for authorization
immediately. Note that persistent search requires a connection to be kept open between
each broker and the LDAP server and may add load to your LDAP server.
ldap.refresh.interval.ms=0