[[introduction]]
== Introduction

_Shield_ is a plugin for Elasticsearch that enables you to easily secure a cluster. With Shield,
you can password-protect your data as well as implement more advanced security measures such as encrypting communications, role-based access control, IP filtering, and auditing. This guide
describes how to install Shield, configure the security features you need, and interact with your secured cluster.

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=== Security for Elasticsearch

Shield protects Elasticsearch clusters by:

* <<preventing-unauthorized-access, Preventing unauthorized access>> with password protection, role-based access control, and IP filtering.
* <<preserving-data-integrity, Preserving the integrity of your data>> with message authentication and SSL/TLS encryption.
* <<maintaining-audit-trail, Maintaining an audit trail>> so you know who's doing what to your
data.

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[[preventing-unauthorized-access]]
==== Preventing Unauthorized Access

To prevent unauthorized access to your Elasticsearch cluster, you must have a way to _authenticate_ users. This simply means that you need a way to validate that a user is who they claim to be. For example, you have to make sure only the person named _Kelsey Andorra_ can sign in as the user `kandorra`. Shield provides a standalone authentication mechanism that enables you to quickly <<enable-basic-auth, password-protect your cluster>>. If you're already using <<ldap, LDAP>>, <<active-directory, Active Directory>>, or <<pki, PKI>>, Shield easily integrates with those systems to perform user authentication.

In many cases, simply authenticating users isn't enough. You also need a way to control what data users have access to and what tasks they can perform. Shield enables you to _authorize_ users by
assigning access _privileges_ to a _role_, and assigning those roles to users. For example, this <<configuring-rbac,role-based access control>> mechanism enables you to specify that the user `kandorra`can only perform read  operations on the `events` index and can't do anything at all with other indices.

Shield also supports <<ip-filtering, IP-based authorization>>. You can whitelist and blacklist specific IP addresses or subnets to control network-level access to a server.

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[[preserving-data-integrity]]
==== Preserving Data Integrity

A critical part of security is keeping confidential data confidential. Elasticsearch has built-in protections against accidental data loss and corruption. However, there's nothing to stop deliberate tampering or data interception. Shield preserves the integrity of your data by <<ssl-tls, encrypting communications>> to and from nodes and <<enable-message-authentication, authenticating messages>> to verify that they have not been tampered with or corrupted in transit. For even greater protection, you can increase the <<ciphers, encryption strength>> and <<separating-node-client-traffic, separate client traffic from node-to-node communications>>.


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[[maintaining-audit-trail]]
==== Maintaining an Audit Trail

Keeping a system secure takes vigilance. By using Shield to maintain an audit trail, you can easily see who is accessing your cluster and what they're doing. By analyzing access patterns and failed attempts to access your cluster, you can gain insights into attempted attacks and data breaches. Keeping an auditable log of the activity in your cluster can also help diagnose operational issues.

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=== Where to Go Next

* <<getting-started, Getting Started>> steps through how to install and start using Shield for basic authentication.
* <<how-shield-works, How Shield Works>> provides more information about how Shield supports user authentication, authorization, and encryption.
* <<configuring-clients-integrations, Configuring Clients and Integrations>> shows you how to
interact with an Elasticsearch cluster protected by Shield.
* <<reference,Reference>> provides detailed information about the access privileges you can grant to users, the settings you can configure for Shield in `elasticsearch.yml`, and the files where Shield configuration information is stored.

=== Have Comments, Questions, or Feedback?

Head over to our https://discuss.elastic.co/c/shield[Shield Discussion Forum] to share your experience, questions, and suggestions.