6.2.2 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 Status Variables

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=#
  Introduced	5.7.17
  System Variable	connection_control_failed_connections_threshold
  Scope	Global
  Dynamic	Yes
  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 6.2.1, “Connection-Control Plugin Installation”.

• connection_control_max_connection_delay

  Command-Line Format	--connection-control-max-connection-delay=#
  Introduced	5.7.17
  System Variable	connection_control_max_connection_delay
  Scope	Global
  Dynamic	Yes
  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 6.2.1, “Connection-Control Plugin Installation”.

• connection_control_min_connection_delay

  Command-Line Format	--connection-control-min-connection-delay=#
  Introduced	5.7.17
  System Variable	connection_control_min_connection_delay
  Scope	Global
  Dynamic	Yes
  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 6.2.1, “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 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.

  This variable was added in MySQL 5.7.17.