opensearch-docs-cn/_security/configuration/configuration.md

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default	Configuring the Security backend	Configuration	5	/security-plugin/configuration/configuration/

Configuring the Security backend

One of the first steps to using the Security plugin is to decide on an authentication backend, which handles steps 2-3 of the authentication flow. The plugin has an internal user database, but many people prefer to use an existing authentication backend, such as an LDAP server, or some combination of the two.

The main configuration file for authentication and authorization backends is config/opensearch-security/config.yml. It defines how the Security plugin retrieves the user credentials, how it verifies these credentials, and how to fetch additional roles from backend systems (optional).

config.yml has three main parts:

opensearch_security:
  dynamic:
    http:
      ...
    authc:
      ...
    authz:
      ...

For a more complete example, see the sample file on GitHub.

HTTP

The http section has the following format:

anonymous_auth_enabled: <true|false>
xff: # optional section
  enabled: <true|false>
  internalProxies: <string> # Regex pattern
  remoteIpHeader: <string> # Name of the header in which to look. Typically: x-forwarded-for
  proxiesHeader: <string>
  trustedProxies: <string> # Regex pattern

If you disable anonymous authentication, the Security plugin won't initialize if you have not provided at least one authc.

Authentication

The authc section has the following format:

<name>:
  http_enabled: <true|false>
  transport_enabled: <true|false>
  order: <integer>
  http_authenticator:
    ...
  authentication_backend:
    ...

An entry in the authc section is called an authentication domain. It specifies where to get the user credentials and against which backend they should be authenticated.

You can use more than one authentication domain. Each authentication domain has a name (for example, basic_auth_internal), enabled flags, and an order. The order makes it possible to chain authentication domains together. The Security plugin uses them in the order that you provide. If the user successfully authenticates with one domain, the Security plugin skips the remaining domains.

http_authenticator specifies which authentication method that you want to use on the HTTP layer.

This is the syntax for defining an authenticator on the HTTP layer:

http_authenticator:
  type: <type>
  challenge: <true|false>
  config:
    ...

These are the allowed values for type:

• basic: HTTP basic authentication. No additional configuration is needed.
• jwt: JSON Web Token (JWT) authentication. Additional configuration is needed. See Configuring JWTs for more information.
• clientcert: Authentication through a client TLS certificate. This certificate must be trusted by one of the root CAs in the truststore of your nodes.

After setting an HTTP authenticator, you must specify against which backend system you want to authenticate the user:

authentication_backend:
  type: <type>
  config:
    ...

These are the possible values for type:

• noop: No further authentication against any backend system is performed. Use noop if the HTTP authenticator has already authenticated the user completely, as in the case of JWT or client certificate authentication.
• internal: Use the users and roles defined in internal_users.yml for authentication.
• ldap: Authenticate users against an LDAP server. This setting requires additional, LDAP-specific configuration settings.

Authorization

After the user has been authenticated, the Security plugin can optionally collect additional roles from backend systems. The authorization configuration has the following format:

authz:
  <name>:
    http_enabled: <true|false>
    transport_enabled: <true|false>
    authorization_backend:
      type: <type>
      config:
        ...

You can define multiple entries in this section the same way as you can for authentication entries. In this case, execution order is not relevant, so there is no order field.

These are the possible values for type:

• noop: Skip this step altogether.
• ldap: Fetch additional roles from an LDAP server. This setting requires additional, LDAP-specific configuration settings.

HTTP basic authentication

To set up HTTP basic authentication, you must enable it in the http_authenticator section of the configuration:

http_authenticator:
  type: basic
  challenge: true

In most cases, you set the challenge flag to true. The flag defines the behavior of the Security plugin if the Authorization field in the HTTP header is not set.

If challenge is set to true, the Security plugin sends a response with status UNAUTHORIZED (401) back to the client. If the client is accessing the cluster with a browser, this triggers the authentication dialog box, and the user is prompted to enter a user name and password.

If challenge is set to false and no Authorization header field is set, the Security plugin does not send a WWW-Authenticate response back to the client, and authentication fails. Consider using this setting if you have more than one challenge http_authenticator keys in your configured authentication domains. This might be the case, for example, when you plan to use basic authentication and OpenID Connect together.

API rate limiting

API rate limiting is typically used to restrict the number of API calls that users can make in a set span of time, thereby helping to manage the rate of API traffic. For security purposes, rate limiting features have the potential to defend against DoS attacks, or repeated login attempts to gain access through trial and error, by restricting failed login attempts.

You have the option to configure the Security plugin for username rate limiting, IP address rate limiting, or both. These configurations are made in the config.yml file. See the following sections for information about each type of rate limiting configuration.

Username rate limiting

This configuration limits login attempts by username. When a login fails, the username is blocked for any machine in the network. The following example shows config.yml file settings configured for username rate limiting:

auth_failure_listeners:
      internal_authentication_backend_limiting:
        type: username
        authentication_backend: internal
        allowed_tries: 3
        time_window_seconds: 60
        block_expiry_seconds: 60
        max_blocked_clients: 100000
        max_tracked_clients: 100000

{% include copy.html %}

The following table describes the individual settings for this type of configuration.

Setting	Description
type	The type of rate limiting. In this case, username.
authentication_backend	The internal backend. Enter internal.
allowed_tries	The number of login attempts allowed before login is blocked. Be aware that increasing the number increases heap usage.
time_window_seconds	The window of time in which the value for allowed_tries is enforced. For example, if allowed_tries is 3 and time_window_seconds is 60, a username has three attempts to log in successfully within a 60-second time span before login is blocked.
block_expiry_seconds	The duration of time that login remains blocked after a failed login. After this time elapses, login is reset and the username can attempt successful login again.
max_blocked_clients	The maximum number of blocked usernames. This limits heap usage to avoid a potential DoS.
max_tracked_clients	The maximum number of tracked usernames that have failed login. This limits heap usage to avoid a potential DoS.

IP address rate limiting

This configuration limits login attempts by IP address. When a login fails, the IP address specific to the machine being used for login is blocked.

There are two steps for configuring IP address rate limiting. First, set the challenge setting to false in the http_authenticator section of the config.yml file.

http_authenticator:
  type: basic
  challenge: false

For more information about this setting, see HTTP basic authentication.

Second, configure the IP address rate limiting settings. The following example shows a completed configuration:

auth_failure_listeners:
      ip_rate_limiting:
        type: ip
        allowed_tries: 1
        time_window_seconds: 20
        block_expiry_seconds: 180
        max_blocked_clients: 100000
        max_tracked_clients: 100000

{% include copy.html %}

The following table describes the individual settings for this type of configuration.

Setting	Description
type	The type of rate limiting. In this case, ip.
allowed_tries	The number of login attempts allowed before login is blocked. Be aware that increasing the number increases heap usage.
time_window_seconds	The window of time in which the value for allowed_tries is enforced. For example, if allowed_tries is 3 and time_window_seconds is 60, an IP address has three attempts to log in successfully within a 60-second time span before login is blocked.
block_expiry_seconds	The duration of time that login remains blocked after a failed login. After this time elapses, login is reset and the IP address can attempt successful login again.
max_blocked_clients	The maximum number of blocked IP addresses. This limits heap usage to avoid a potential DoS.
max_tracked_clients	The maximum number of tracked IP addresses that have failed login. This limits heap usage to avoid a potential DoS.

Backend configuration examples

The default config/opensearch-security/config.yml file included in your OpenSearch distribution contains many configuration examples. Use these examples as a starting point and customize them to your needs.

Next steps

To learn about configuring supported authentication backends, see the relevant topic for each type in the Authentication backends documentation.