#!/bin/bash
#
# Usage: ./check_fail2ban
###############################################################################################
# Description: 
#		This plugin will check the status of Fail2ban.  
#
# Created:      2008-10-25 (Sebastian Mueller)
#
# Changes:      2008-10-26 fixed some issues (Sebastian Mueller)
# Changes:      2009-01-25 add the second check, when server is not replying and the
#		process is hang-up (Sebastian Mueller)
#
# please visit my website http://www.elchtest.eu or my personal WIKI http://wiki.elchtest.eu
#
################################################################################################
# if you have any questions, send a mail to linux@krabbe-offline.de 
#
# this script is for my personal use. read the script before running/using it!!!
#
#
# YOU HAVE BEEN WARNED. THIS MAY DESTROY YOUR MACHINE. I ACCEPT NO RESPONSIBILITY.
###############################################################################################


SECOND_CHECK=0 
STATE_OK=0
STATE_CRITICAL=2

######################################################################
# Read the Status from fail2ban-client 
######################################################################
check_processes_fail2ban()
{
        
  F2B=`sudo -u root fail2ban-client ping | awk -F " " '{print $3}'`
  exit_fail2ban=0

  if  [[ $F2B = "pong" ]]; then
   exit_fail2ban=$STATE_OK
 else
 exit_fail2ban=$STATE_CRITICAL
 fi

}
######################################################################
# first check in the Background, PID will be killed when no response
# after 10 seconds, might be possible, otherwise the script will be
# present in your memory all the time
######################################################################

check_processes_fail2ban &
pid=$!

typeset -i i=0
while ps $pid >/dev/null
do
 sleep 1
 i=$i+1
if [ $i -ge 10 ]
 then
 kill $pid 
   SECOND_CHECK=1
   exit_fail2ban=$STATE_CRITICAL
   break
fi
done

######################################################################
# when the Server response (does not mean the FAIL2BAN is working)
# in the first step, then it will run again and test the Service 
# and provide the real status
######################################################################


if [ $SECOND_CHECK -eq 0  ]; then
  check_processes_fail2ban
 elif [ $SECOND_CHECK -eq 1 ]; then
  exit_fail2ban=$STATE_CRITICAL
fi



######################################################################
# Main Menu
######################################################################


final_exit=$exit_fail2ban
if [ $final_exit -eq 0  ]; then
  echo "SYSTEM OK - Fail2ban is working normally"
  exitstatus=$STATE_OK
elif [ $final_exit -ne "0" ]; then
  echo "SYSTEM WARNING - Fail2Ban is not working"
######################################################################
# If don't have a Nagios Server for monitoring, remove the comment and
# add your Mail Address. You can check it with a Cron Job once an hour.
# put a txt file on your server and describe how to fix the issue, this 
# could be attached to the mail.
######################################################################
#  mutt -s "FAIL2BAN NOT WORKING" your@example.com < /home/f2ban.txt

  exitstatus=$STATE_CRITICAL
fi
exit $exitstatus