#### 6.4.2.2 Connection-Control System and Status Variables

 This section describes the system and status variables that the `CONNECTION_CONTROL` plugin provides to enable its operation to be configured and monitored.

* [Connection-Control System Variables](connection-control-variables.html#connection-control-plugin-system-variables)

* [Connection-Control Status Variables](connection-control-variables.html#connection-control-plugin-status-variables)

##### Connection-Control System Variables

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 If the `CONNECTION_CONTROL` plugin is installed, it exposes these system variables:

* []() [`connection_control_failed_connections_threshold`](connection-control-variables.html#sysvar_connection_control_failed_connections_threshold)

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  |                         Command-Line Format                          |                                            `--connection-control-failed-connections-threshold=#`                                            |
  |----------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------|
  |                           System Variable                            |`[connection_control_failed_connections_threshold](connection-control-variables.html#sysvar_connection_control_failed_connections_threshold)`|
  |                                Scope                                 |                                                                   Global                                                                    |
  |                               Dynamic                                |                                                                     Yes                                                                     |
  |[`SET_VAR`](optimizer-hints.html#optimizer-hints-set-var) Hint Applies|                                                                     No                                                                      |
  |                                 Type                                 |                                                                   Integer                                                                   |
  |                            Default Value                             |                                                                     `3`                                                                     |
  |                            Minimum Value                             |                                                                     `0`                                                                     |
  |                            Maximum Value                             |                                                                `2147483647`                                                                 |

   The number of consecutive failed connection attempts permitted to accounts before the server adds a delay for subsequent connection attempts:

  * If the variable has a nonzero value *`N`*, the server adds a delay beginning with consecutive failed attempt *`N`*+1. If an account has reached the point where connection responses are delayed, a delay also occurs for the next subsequent successful connection.

  * Setting this variable to zero disables failed-connection counting. In this case, the server never adds delays.

   For information about how [`connection_control_failed_connections_threshold`](connection-control-variables.html#sysvar_connection_control_failed_connections_threshold) interacts with other connection-control system and status variables, see [Section 6.4.2.1, “Connection-Control Plugin Installation”](connection-control-installation.html).

* []() [`connection_control_max_connection_delay`](connection-control-variables.html#sysvar_connection_control_max_connection_delay)

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  |                         Command-Line Format                          |                                        `--connection-control-max-connection-delay=#`                                        |
  |----------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------|
  |                           System Variable                            |`[connection_control_max_connection_delay](connection-control-variables.html#sysvar_connection_control_max_connection_delay)`|
  |                                Scope                                 |                                                           Global                                                            |
  |                               Dynamic                                |                                                             Yes                                                             |
  |[`SET_VAR`](optimizer-hints.html#optimizer-hints-set-var) Hint Applies|                                                             No                                                              |
  |                                 Type                                 |                                                           Integer                                                           |
  |                            Default Value                             |                                                        `2147483647`                                                         |
  |                            Minimum Value                             |                                                           `1000`                                                            |
  |                            Maximum Value                             |                                                        `2147483647`                                                         |
  |                                 Unit                                 |                                                       `milliseconds`                                                        |

   The maximum delay in milliseconds for server response to failed connection attempts, if [`connection_control_failed_connections_threshold`](connection-control-variables.html#sysvar_connection_control_failed_connections_threshold) is greater than zero.

   For information about how [`connection_control_max_connection_delay`](connection-control-variables.html#sysvar_connection_control_max_connection_delay) interacts with other connection-control system and status variables, see [Section 6.4.2.1, “Connection-Control Plugin Installation”](connection-control-installation.html).

* []() [`connection_control_min_connection_delay`](connection-control-variables.html#sysvar_connection_control_min_connection_delay)

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  |                         Command-Line Format                          |                                        `--connection-control-min-connection-delay=#`                                        |
  |----------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------|
  |                           System Variable                            |`[connection_control_min_connection_delay](connection-control-variables.html#sysvar_connection_control_min_connection_delay)`|
  |                                Scope                                 |                                                           Global                                                            |
  |                               Dynamic                                |                                                             Yes                                                             |
  |[`SET_VAR`](optimizer-hints.html#optimizer-hints-set-var) Hint Applies|                                                             No                                                              |
  |                                 Type                                 |                                                           Integer                                                           |
  |                            Default Value                             |                                                           `1000`                                                            |
  |                            Minimum Value                             |                                                           `1000`                                                            |
  |                            Maximum Value                             |                                                        `2147483647`                                                         |
  |                                 Unit                                 |                                                       `milliseconds`                                                        |

   The minimum delay in milliseconds for server response to failed connection attempts, if [`connection_control_failed_connections_threshold`](connection-control-variables.html#sysvar_connection_control_failed_connections_threshold) is greater than zero.

   For information about how [`connection_control_min_connection_delay`](connection-control-variables.html#sysvar_connection_control_min_connection_delay) interacts with other connection-control system and status variables, see [Section 6.4.2.1, “Connection-Control Plugin Installation”](connection-control-installation.html).

##### Connection-Control Status Variables

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 If the `CONNECTION_CONTROL` plugin is installed, it exposes this status variable:

* []() [`Connection_control_delay_generated`](connection-control-variables.html#statvar_Connection_control_delay_generated)

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   The number of times the server added a delay to its response to a failed connection attempt. This does not count attempts that occur before reaching the threshold defined by the [`connection_control_failed_connections_threshold`](connection-control-variables.html#sysvar_connection_control_failed_connections_threshold) system variable.

   This variable provides a simple counter. For more detailed connection-control monitoring information, examine the `INFORMATION_SCHEMA` [`CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS`](information-schema-connection-control-failed-login-attempts-table.html) table; see [Section 26.6.2, “The INFORMATION\_SCHEMA CONNECTION\_CONTROL\_FAILED\_LOGIN\_ATTEMPTS Table”](information-schema-connection-control-failed-login-attempts-table.html).

   Assigning a value to [`connection_control_failed_connections_threshold`](connection-control-variables.html#sysvar_connection_control_failed_connections_threshold) at runtime resets [`Connection_control_delay_generated`](connection-control-variables.html#statvar_Connection_control_delay_generated) to zero.

