Active Directory and LDAP can be used for both authentication and authorization (the `authc` and `authz` sections of the configuration, respectively). Authentication checks whether the user has entered valid credentials. Authorization retrieves any backend roles for the user.
In most cases, you want to configure both authentication and authorization. You can also use authentication only and map the users retrieved from LDAP directly to Security plugin roles.
*`docker-compose.yml` defines a single OpenSearch node, an LDAP server, and a PHP administration tool for the LDAP server.
You can access the administration tool at https://localhost:6443. Acknowledge the security warning and log in using `cn=admin,dc=example,dc=org` and `changethis`.
*`directory.ldif` seeds the LDAP server with three users and two groups.
`psantos` is in the `Administrator` and `Developers` groups. `jroe` and `jdoe` are in the `Developers` group. The Security plugin loads these groups as backend roles.
*`roles_mapping.yml` maps the `Administrator` and `Developers` LDAP groups (as backend roles) to security roles so that users gain the appropriate permissions after authenticating.
*`internal_users.yml` removes all default users except `administrator` and `kibanaserver`.
*`config.yml` includes all necessary LDAP settings.
If you try the same request as `jroe`, it fails. The `Developers` group is mapped to the `readall`, `manage_snapshots`, and `kibana_user` roles and has no write permissions.
This request succeeds, because the `Developers` group is mapped to the `readall` role.
1. If you want to examine the contents of the various containers, run `docker ps` to find the container ID and then `docker exec -it <container-id> /bin/bash`.
You can configure more than one server here. If the Security plugin cannot connect to the first server, it tries to connect to the remaining servers sequentially.
To configure connection and response timeouts to your Active Directory server, use the following (values are in milliseconds):
```yml
config:
connect_timeout: 5000
response_timeout: 0
```
If your server supports two-factor authentication (2FA), the default timeout settings might result in login errors. You can increase `connect_timeout` to accommodate the 2FA process. Setting `response_timeout` to 0 (the default) indicates an indefinite waiting period.
By default, the Security plugin validates the TLS certificate of the LDAP servers against the root CA configured in `opensearch.yml`, either as a PEM certificate or a truststore:
You can also use a separate root CA in PEM format.
When configuring a separate root CA for LDAP, make sure to include the setting in all instances of the LDAP `config:` settings, including in both the `authc` and `authz` options of the configuration.
{: .note}
To configure a separate root CA, use one of the following configuration options:
If you use TLS client authentication, the Security plugin sends the PEM certificate of the node, as configured in `opensearch.yml`. Set one of the following configuration options:
`pemkey_filepath` | Absolute path to the file containing the private key of your certificate.
`pemkey_content` | The content of the private key of your certificate. Cannot be used when `pemkey_filepath` is set.
`pemkey_password` | The password of your private key, if any.
`pemcert_filepath` | Absolute path to the client certificate.
`pemcert_content` | The content of the client certificate. Cannot be used when `pemcert_filepath` is set.
### Enabled ciphers and protocols
You can limit the allowed ciphers and TLS protocols for the LDAP connection. For example, you can allow only strong ciphers and limit the TLS versions to the most recent ones:
```yml
ldap:
http_enabled: true
transport_enabled: true
...
authentication_backend:
type: ldap
config:
enabled_ssl_ciphers:
- "TLS_DHE_RSA_WITH_AES_256_CBC_SHA"
- "TLS_DHE_DSS_WITH_AES_128_CBC_SHA256"
enabled_ssl_protocols:
- "TLSv1.1"
- "TLSv1.2"
```
Name | Description
:--- | :---
`enabled_ssl_ciphers` | Array, enabled TLS ciphers. Only the Java format is supported.
`enabled_ssl_protocols` | Array, enabled TLS protocols. Only the Java format is supported.
---
## Use Active Directory and LDAP for authentication
To use Active Directory/LDAP for authentication, first configure a respective authentication domain in the `authc` section of `config/opensearch-security/config.yml`:
If the query is successful, the Security plugin retrieves the user name from the LDAP entry. You can specify which attribute from the LDAP entry the Security plugin should use as the user name:
`usersearch` | The actual LDAP query that the Security plugin executes when trying to authenticate a user. The variable {0} is substituted with the user name.
`username_attribute` | The Security plugin uses this attribute of the directory entry to look for the user name. If set to null, the DN is used (default).
## Use Active Directory and LDAP for authorization
To use Active Directory/LDAP for authorization, first configure a respective authorization domain in the `authz` section of `config.yml`:
```yml
authz:
ldap:
http_enabled: true
transport_enabled: true
authorization_backend:
type: ldap
config:
...
```
Authorization is the process of retrieving backend roles for an authenticated user from an LDAP server. This is typically the same servers that you use for authentication, but you can also use a different server. The only requirement is that the user you use to fetch the roles actually exists on the LDAP server.
Because the Security plugin always checks if a user exists in the LDAP server, you must also configure `userbase`, `usersearch` and `username_attribute` in the `authz` section.
Authorization works similarly to authentication. The Security plugin issues an LDAP query containing the user name against the role subtree of the LDAP tree.
The Security plugin first takes the LDAP query for fetching roles ("rolesearch") and substitutes any variables found in the query. For example, for a standard Active Directory installation, you would use the following role search:
-`{1}` is substituted with the user name, as defined by the `username_attribute` setting.
-`{2}` is substituted with an arbitrary attribute value from the authenticated user's directory entry.
The variable `{2}` refers to an attribute from the user's directory entry. The attribute that you should use is specified by the `userroleattribute` setting:
If this is not set, the DN of the role entry is used. You can now use this role name for mapping it to one or more of the Security plugin roles, as defined in `roles_mapping.yml`.
This approach can be combined with querying the role subtree. The Security plugin fetches the roles from the user's role attribute and then executes the role search.
By default, the Security plugin reads all LDAP user attributes and makes them available for index name variable substitution and DLS query variable substitution. If your LDAP entries have a lot of attributes, you might want to control which attributes should be made available. The fewer the attributes, the better the performance.
`custom_attr_maxval_len` | Integer. Specifies the maximum allowed length of each attribute. All attributes longer than this value are discarded. A value of `0` disables custom attributes altogether. Default is 36.
If you are using multiple authentication methods, it can make sense to exclude certain users from the LDAP role lookup.
Consider the following scenario for a typical OpenSearch Dashboards setup: All OpenSearch Dashboards users are stored in an LDAP/Active Directory server.
However, you also have an OpenSearch Dashboards server user. OpenSearch Dashboards uses this user to manage stored objects and perform monitoring and maintenance tasks. You do not want to add this user to your Active Directory installation, but rather store it in the Security plugin internal user database.
In this case, it makes sense to exclude the OpenSearch Dashboards server user from the LDAP authorization because we already know that there is no corresponding entry. You can use the `skip_users` configuration setting to define which users should be skipped. Wildcards and regular expressions are supported:
### (Advanced) Exclude roles from nested role lookups
If the users in your LDAP installation have a large number of roles, and you have the requirement to resolve nested roles as well, you might run into performance issues.
In most cases, however, not all user roles are related to OpenSearch and OpenSearch Dashboards. You might need only a couple of roles. In this case, you can use the nested role filter feature to define a list of roles that are filtered out from the list of the user's roles. Wildcards and regular expressions are supported.
This has an effect only if `resolve_nested_roles` is `true`:
`rolesearch` | The actual LDAP query that the Security plugin executes when trying to determine the roles of a user. You can use three variables here (see below).
`userroleattribute` | The attribute in a user entry to use for `{2}` variable substitution.
`userrolename` | If the roles/groups of a user are not stored in the groups subtree, but as an attribute of the user's directory entry, define this attribute name here.
`rolename` | The attribute of the role entry that should be used as the role name.
`resolve_nested_roles` | Boolean. Whether or not to resolve nested roles. Default is `false`.
`max_nested_depth` | Integer. When `resolve_nested_roles` is `true`, this defines the maximum number of nested roles to traverse. Setting smaller values can reduce the amount of data retrieved from LDAP and improve authentication times at the cost of failing to discover deeply nested roles. Default is `30`.
`skip_users` | Array of users that should be skipped when retrieving roles. Wildcards and regular expressions are supported.
`nested_role_filter` | Array of role DNs that should be filtered before resolving nested roles. Wildcards and regular expressions are supported.
`rolesearch_enabled` | Boolean. Enable or disable the role search. Default is `true`.
`custom_attr_maxval_len` | Integer. Specifies the maximum allowed length of each attribute. All attributes longer than this value are discarded. A value of `0` disables custom attributes altogether. Default is 36.
