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Flapping in EMQX refers to a situation where an MQTT client rapidly connects and disconnects from the broker in a short period of time. The flapping mechanism is to detect flapping clients and to disconnect the client from a connection.

For example, if you want to mark clients that make 15 connection attempts within a 1-minute window as flapping clients, and then ban the detected clients from connecting to EMQX for 5 minutes, you can work with the code below:

flapping_detect {
  max_count  =  15
  window_time  =  1m
  ban_time  =  5m


  • max_count is to set the maximum number of connection attempts allowed from a client within a specified time window (defined by window_time)
  • window_time is to set the time window in which the maximum number of connection attempts from a client are counted.
  • ban_time is to set the duration for which a client is banned from connecting to the EMQX after it has been detected as flapping.


To customize the settings via Dashboard, click Access Control -> Blacklist on the left navigation menu of the Dashboard. Once you configured these items with Dashboard, your settings will override the same configuration items in emqx.conf.

EMQX has offered more configuration items to better serve customized needs, you can continue to read Configuration Manual.