Audit logs let you track access to your OpenSearch cluster and are useful for compliance purposes or in the aftermath of a security breach. You can configure the categories to be logged, the detail level of the logged messages, and where to store the logs.
To enable audit logging:
1. Add the following line to `opensearch.yml` on each node:
This setting stores audit logs on the current cluster. For other storage options, see [Audit Log Storage Types]({{site.url}}{{site.baseurl}}/security/audit-logs/storage-types/).
After this initial setup, you can use OpenSearch Dashboards to manage your audit log categories and other settings. In OpenSearch Dashboards, select **Security** and then **Audit logs**.
An alternative is to specify initial settings for audit logging in the `audit.yml` and `opensearch.yml` files (which file depends on the setting---see [Audit log settings](#audit-log-settings)). Thereafter, you can use Dashboards or the [Audit logs]({{site.url}}{{site.baseurl}}/security/access-control/api/#audit-logs) API to manage and update settings.
Audit logging records events in two ways: HTTP requests (REST) and the transport layer. The following table provides descriptions of tracked events and whether or not they are logged on the REST or transport layer.
Event | Logged on REST | Logged on transport | Description
:--- | :--- | :--- | :---
`FAILED_LOGIN` | Yes | Yes | The credentials of a request could not be validated, most likely because the user does not exist or the password is incorrect.
`AUTHENTICATED` | Yes | Yes | A user successfully authenticated.
`opensearch_SECURITY_INDEX_ATTEMPT` | No | Yes | An attempt was made to modify the Security plugin internal user and privileges index without the required permissions or TLS admin certificate.
`BAD_HEADERS` | Yes | Yes | An attempt was made to spoof a request to OpenSearch with the Security plugin internal headers.
The following default log settings work well for most use cases. However, you can change settings to save storage space or adapt the information to your exact needs.
By default, the Security plugin includes the body of the request (if available) for both REST and the transport layer. If you do not want or need the request body, you can disable it:
By default, the Security plugin logs all indexes affected by a request. Because index names can be aliases and contain wildcards/date patterns, the Security plugin logs the index name that the user submitted *and* the actual index name to which it resolves.
This change can create an extremely large number of events in the audit logs, so we don't recommend enabling this setting if you frequently use the `_bulk` API.
By default, the Security plugin logs events from all users but excludes the internal OpenSearch Dashboards server user `kibanaserver`. You can exclude other users:
For a reference on the date pattern format, see the [Joda DateTimeFormat documentation](https://www.joda.org/joda-time/apidocs/org/joda/time/format/DateTimeFormat.html).
The Search plugin logs events asynchronously, which minimizes the performance impact on your cluster. The plugin uses a fixed thread pool to log events:
The default setting is `10`. Setting this value to `0` disables the thread pool, which means the plugin logs events synchronously. To set the maximum queue length per thread:
