Replace API_KEY and EMAIL (2 instances each) with appropriate values.

gistfile1.txt

# Fail2Ban configuration file
#
# Author: Norman Yee
#
# $Revision$
#
 
[Definition]
 
# Option:  actionstart
# Notes.:  command executed once at the start of Fail2Ban.
# Values:  CMD
#
actionstart =
 
# Option:  actionstop
# Notes.:  command executed once at the end of Fail2Ban
# Values:  CMD
#
actionstop =
 
# Option:  actioncheck
# Notes.:  command executed once before each actionban command
# Values:  CMD
#
actioncheck =
 
# Option:  actionban
# Notes.:  command executed when banning an IP. Take care that the
#          command is executed with Fail2Ban user rights.
# Tags:    <ip>  IP address
#          <failures>  number of failures
#          <time>  unix timestamp of the ban time
# Values:  CMD
#
actionban = curl -s --data "a=ban&tkn=API_KEY&email=EMAIL&key=<ip>" https://www.cloudflare.com/api_json.html
 
# Option:  actionunban
# Notes.:  command executed when unbanning an IP. Take care that the
#          command is executed with Fail2Ban user rights.
# Tags:    &lt;ip&gt;  IP address
#          &lt;failures&gt;  number of failures
#          &lt;time&gt;  unix timestamp of the ban time
# Values:  CMD
#
actionunban = curl -s --data "a=nul&tkn=API_KEY&email=EMAIL&key=<ip>" https://www.cloudflare.com/api_json.html