Secure Cross-Cluster Search

Introduction

Cross-Cluster Search (CCS) allows you to search across multiple Elasticsearch clusters as if they were a single cluster. This is particularly useful for federated search use cases where data is distributed across different clusters. However, to ensure the security of such operations, it is imperative to implement proper security measures.

Setting Up Cross-Cluster Search

Before diving into secure configurations, let's first understand how to set up Cross-Cluster Search. Here are the foundational steps:

PUT /_cluster/settings
{
  "persistent": {
    "cluster": {
      "remote": {
        "remote_cluster": {
          "seeds": ["remote_host:9300"]
        }
      }
    }
  }
}

Implementing Security

To ensure secure Cross-Cluster Search, follow these steps:

1. Enable TLS/SSL

Secure communication between nodes using TLS/SSL. Modify the Elasticsearch configuration files on all clusters:

xpack.security.transport.ssl.enabled: true
xpack.security.transport.ssl.verification_mode: certificate
xpack.security.transport.ssl.key: certs/node.key
xpack.security.transport.ssl.certificate: certs/node.crt
xpack.security.transport.ssl.certificate_authorities: [ "certs/ca.crt" ]

2. Configure Role-Based Access Control (RBAC)

Define roles and permissions specific to Cross-Cluster Search:

PUT /_security/role/remote_search_role
{
  "cluster": ["cross_cluster_search"],
  "indices": [
    {
      "names": ["*"],
      "privileges": ["read"]
    }
  ]
}

3. Create Users with Specific Roles

Create users and assign them the roles defined above:

POST /_security/user/remote_search_user
{
  "password" : "password123",
  "roles" : [ "remote_search_role" ],
  "full_name" : "Remote Search User",
  "email" : "user@example.com"
}

Performing Secure Cross-Cluster Search

Once the setup is complete, you can perform a secure cross-cluster search:

GET /remote_cluster:index_name/_search
{
  "query": {
    "match_all": {}
  }
}

Monitoring and Auditing

It's crucial to monitor and audit cross-cluster search activities to ensure security and compliance:

1. Enable Audit Logging

Modify the Elasticsearch configuration to enable audit logging:

xpack.security.audit.enabled: true
xpack.security.audit.outputs: [ index, logfile ]

2. Regularly Review Logs

Review the audit logs regularly to detect any suspicious activities.

Conclusion

Implementing secure Cross-Cluster Search in Elasticsearch involves enabling TLS/SSL, defining roles and permissions, creating specific users, and monitoring activities. These steps ensure that your cross-cluster search operations are both efficient and secure.