8.4.2.2 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

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

connection_control_failed_connections_threshold

Command-Line Format	`--connection-control-failed-connections-threshold=#`
System Variable	`connection_control_failed_connections_threshold`
Scope	Global
Dynamic	Yes
`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 interacts with other connection-control system and status variables, see Section 8.4.2.1, “Connection-Control Plugin Installation”.

connection_control_max_connection_delay

Command-Line Format	`--connection-control-max-connection-delay=#`
System Variable	`connection_control_max_connection_delay`
Scope	Global
Dynamic	Yes
`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 is greater than zero.

For information about how connection_control_max_connection_delay interacts with other connection-control system and status variables, see Section 8.4.2.1, “Connection-Control Plugin Installation”.

connection_control_min_connection_delay

Command-Line Format	`--connection-control-min-connection-delay=#`
System Variable	`connection_control_min_connection_delay`
Scope	Global
Dynamic	Yes
`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 is greater than zero.

For information about how connection_control_min_connection_delay interacts with other connection-control system and status variables, see Section 8.4.2.1, “Connection-Control Plugin Installation”.

Connection-Control Status Variables

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

Connection_control_delay_generated
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 system variable.
This variable provides a simple counter. For more detailed connection-control monitoring information, examine the INFORMATION_SCHEMA CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS table; see Section 28.6.2, “The INFORMATION_SCHEMA CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS Table”.
Assigning a value to connection_control_failed_connections_threshold at runtime resets Connection_control_delay_generated to zero.