Configuring Elasticsearch Authentication with LDAPS

LDAP (Lightweight Directory Access Protocol) is a popular method for centralizing user authentication and access control across an organization. Configuring Elasticsearch to use LDAP over a secure connection (LDAPS) adds an additional layer of security by encrypting communication between Elasticsearch and the LDAP server. This article provides a step-by-step guide to setting up LDAPS for Elasticsearch authentication. 

Prerequisites

• Elasticsearch Security Features: Ensure Elasticsearch security features (authentication, TLS) are enabled. This is included in the default distribution of Elasticsearch.
• LDAPS Server: You need access to an LDAP server that supports secure connections (e.g., Active Directory, OpenLDAP).
• Certificates: A valid SSL/TLS certificate must be installed on your LDAP server and accessible by Elasticsearch.

Step 1: Enable TLS in Elasticsearch

Before configuring LDAPS, ensure Elasticsearch itself is configured for secure communication. Update the elasticsearch.yml file with the following settings:

xpack.security.enabled: true
xpack.security.transport.ssl.enabled: true
xpack.security.http.ssl.enabled: true
xpack.security.http.ssl.keystore.path: "/path/to/your/elasticsearch-keystore.p12"
xpack.security.http.ssl.truststore.path: "/path/to/your/elasticsearch-truststore.p12"

Restart the Elasticsearch service to apply the changes:

systemctl restart elasticsearch

Step 2: Configure the LDAPS Realm

Add the following LDAP realm configuration to elasticsearch.yml:

xpack.security.authc.realms.ldap.my_ldap:
  order: 0
  url: "ldaps://<ldap-server>:636"
  bind_dn: "cn=admin,dc=example,dc=com"
  secure_bind_password: "your_password"
  user_search:
    base_dn: "dc=example,dc=com"
  group_search:
    base_dn: "dc=example,dc=com"
  files:
    role_mapping: "config/role_mapping.yml"
  ssl:
    certificate_authorities: ["/path/to/ldap-ca.pem"]

Key points:

• url: Use ldaps:// and the port number (typically 636 for LDAPS).
• bind_dn and secure_bind_password: Credentials used to bind to the LDAP server.
• user_search and group_search: Define the search base DN for users and groups.
• role_mapping: File to map LDAP groups to Elasticsearch roles.
• certificate_authorities: Path to the LDAP server’s CA certificate to verify the server’s identity.

Step 3: Define Role Mappings

Create or edit the role_mapping.yml file in the Elasticsearch config directory to map LDAP groups to Elasticsearch roles:

admin:
  - "cn=admins,dc=example,dc=com"
read_only:
  - "cn=readers,dc=example,dc=com"

Restart Elasticsearch for the changes to take effect:

systemctl restart elasticsearch

Step 4: Test the LDAPS Configuration

To verify that LDAPS authentication is working, use the following API to authenticate a user:

curl -u <username>:<password> -X GET "https://<elasticsearch-host>:9200/_security/_authenticate?pretty"

If successful, the response will include the user’s details and roles retrieved from the LDAP server.

Step 5: Troubleshooting

• Certificate Issues: Ensure the LDAP server’s certificate is valid and trusted by Elasticsearch.
• LDAP Connection Errors: Verify the LDAP server is reachable and LDAPS is enabled. Test with tools like ldapsearch to debug connection issues.
• Logging: Increase logging levels for LDAP realms by updating log4j2.properties:
• logger.ldap.name = org.elasticsearch.xpack.security.authc.ldap
• logger.ldap.level = debug

Conclusion

Configuring Elasticsearch with LDAPS ensures secure and centralized user authentication. By leveraging LDAPS, organizations can strengthen their security posture while integrating Elasticsearch with existing directory services. Follow these steps to set up and test your configuration, and remember to monitor and maintain your LDAP infrastructure for optimal performance.