fail2ban/config/action.d/hostsdeny.conf

# Fail2Ban configuration file
#
# Author: Cyril Jaquier
# Edited for cross platform by: James Stout, Yaroslav Halchenko and Daniel Black
#
#

[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:    See jail.conf(5) man page
# Values:  CMD
#
actionban = printf %%b "<daemon_list>: <_ip_value>\n" >> <file>

# Option:  actionunban
# Notes.:  command executed when unbanning an IP. Take care that the
#          command is executed with Fail2Ban user rights.
# Tags:    See jail.conf(5) man page
# Values:  CMD
#
actionunban = IP=$(echo "<_ip_value>" | sed 's/[][\.]/\\\0/g') && sed -i "/^<daemon_list>: $IP$/d" <file>

[Init]

# Option:  file
# Notes.:  hosts.deny file path.
# Values:  STR  Default:  /etc/hosts.deny
#
file = /etc/hosts.deny

# Option:  daemon_list
# Notes:   The list of services that this action will deny. See the man page
#          for hosts.deny/hosts_access. Default is all services.
# Values:  STR  Default: ALL
daemon_list = ALL

# internal variable IP (to differentiate the IPv4 and IPv6 syntax, where it is enclosed in brackets):
_ip_value = <ip>

[Init?family=inet6]
_ip_value = [<ip>]