API rate limiting
- Username rate limiting
- IP address rate limiting

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, by restricting failed login attempts, have the potential to defend against denial of service (DoS) attacks or repeated login attempts intended to gain access through trial and error.

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

The username rate limiting configuration limits login attempts by username. When a login fails, the username is blocked from use by 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

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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 attempts are blocked. Be aware that increasing the number increases heap usage.
`time_window_seconds`	The window of time during which the value for `allowed_tries` is enforced. For example, if `allowed_tries` is `3` and `time_window_seconds` is `60`, a username has 3 attempts to log in successfully within a 60-second time span before login attempts are blocked.
`block_expiry_seconds`	The window of time during which login attempts remain blocked after a failed login. After this time elapses, login is reset and the username can attempt to log in again.
`max_blocked_clients`	The maximum number of blocked usernames. This limits heap usage to avoid a potential DoS attack.
`max_tracked_clients`	The maximum number of tracked usernames with failed login attempts. This limits heap usage to avoid a potential DoS attack.

IP address rate limiting

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

Configuring IP address rate limiting involves two steps. 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

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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 attempts are blocked. Be aware that increasing the number increases heap usage.
`time_window_seconds`	The window of time during 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 3 attempts to log in successfully within a 60-second time span before login attempts are blocked.
`block_expiry_seconds`	The window of time during which login attempts remain blocked after a failed login. After this time elapses, login is reset and the IP address can attempt to log in again.
`max_blocked_clients`	The maximum number of blocked IP addresses. This limits heap usage to avoid a potential DoS attack.
`max_tracked_clients`	The maximum number of tracked IP addresses with failed login attempts. This limits heap usage to avoid a potential DoS attack.
`ignore_hosts`	A list of IP addresses or hostname patterns to ignore for rate limiting. `config.dynamic.hosts_resolver_mode` must be set to `ip-hostname` to support hostname matching.