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](storage-types/).
2. Restart each node.
After this initial setup, you can use OpenSearch Dashboards to manage your audit log categories and other settings. In OpenSearch Dashboards, choose **Security**, **Audit logs**.
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## Tracked events
Audit logging records events in two ways: HTTP requests (REST) and the 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.
`MISSING_PRIVILEGES` | No | Yes | The user does not have the required permissions to execute the request.
`GRANTED_PRIVILEGES` | No | Yes | A user made a successful request to OpenSearch.
`SSL_EXCEPTION` | Yes | Yes | An attempt was made to access OpenSearch without a valid SSL/TLS certificate.
`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.
These default log settings work well for most use cases, but 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 indices 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 a massive number of events in the audit logs, so we don't recommend enabling this setting if you make heavy use of the `_bulk` API.
## Exclude requests
You can exclude certain requests from being logged completely, by either configuring actions (for transport requests) and/or HTTP request paths (REST):
By default, the security plugin logs events from all users, but excludes the internal OpenSearch Dashboards server user `kibanaserver`. You can exclude other users:
By default, the security plugin stores audit events in a daily rolling index named `auditlog-YYYY.MM.dd`. You can configure the name of the index in `opensearch.yml`:
For a reference on the date pattern format, see the [Joda DateTimeFormat documentation](http://www.joda.org/joda-time/apidocs/org/joda/time/format/DateTimeFormat.html).
## (Advanced) Tune the thread pool
The Search plugin logs events asynchronously, which keeps performance impact on your cluster minimal. The plugin uses a fixed thread pool to log events. You can define the number of threads in the pool in `opensearch.yml`:
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: