meta-refresh

The metarefresh challenge asks the browser to refresh the page after a delay.

The challenge uses either an HTML meta refresh or an HTTP Refresh header. Both direct the browser to the challenge endpoint after difficulty + 1 seconds. The server requires at least 800 milliseconds per unit of difficulty before it accepts the response.

Configuration

Add a browser rule to the bots list:

bots:
  - name: generic-browser
    expression: userAgent.matches("Mozilla|Opera")
    action: CHALLENGE
    challenge:
      algorithm: metarefresh
      difficulty: 1

With difficulty: 1, the browser refreshes after two seconds. The expression matches a User-Agent that contains Mozilla or Opera. See policies for rule order and actions. See expressions for other match conditions.