Description
-----------
This plugin checks if the fail2ban server is running and how many IPs are currently banned.
You can use this plugin to monitor all the jails or just a specific jail.


How to use
----------
Just have to run the following command:
    $ ./check_fail2ban --help

If you need to use this script with NRPE you just have to do the
following steps:

1 allow your user to run the script with the sudo rights. Just add
  something like that in your /etc/sudoers (use visudo) :
        nagios ALL=(ALL) NOPASSWD: /<path-to>/check_fail2ban

2 then just add this kind of line in your NRPE config file :
  command[check_fail2ban]=/usr/bin/sudo /<path-to>/check_fail2ban

3 don't forget to restart your NRPE daemon

/!\ be careful to let no one able to update the check_fail2ban ;)
------------------------------------------------------------------------------


Notes (from f2ban.txt)
-----
It seems that Fail2ban is currently not working, please login and check

HELP:

1.) stop the Service
/etc/init.d/fail2ban stop

2.) delete the socket if available
rm /var/run/fail2ban/fail2ban.sock

3.) start the Service
/etc/init.d/fail2ban start

4.) check if fail2ban is working
fail2ban-client ping
Answer should be "pong"

5.) if the answer is not "pong" run away or  CRY FOR HELP ;-)


Help
----

Usage: /<path-to>/check_fail2ban [-p] [-D "CHECK FAIL2BAN ACTIVITY"] [-v] [-c 2] [-w 1] [-s /<path-to>/socket] [-P /usr/bin/fail2ban-client]

Options:
 -h, --help
    Print detailed help screen
 -V, --version
    Print version information
 -D, --display=STRING
    To modify the output display
    default is "CHECK FAIL2BAN ACTIVITY"
 -P, --path-fail2ban_client=STRING
    Specify the path to the tw_cli binary
    default value is /usr/bin/fail2ban-client
 -c, --critical=INT
    Specify a critical threshold
    default is 2
 -w, --warning=INT
    Specify a warning threshold
    default is 1
 -s, --socket=STRING
    Specify a socket path
    default is unset
 -p, --perfdata
    If you want to activate the perfdata output
 -v, --verbose
    Show details for command-line debugging (Nagios may truncate the output)


Example
-------

# for a specific jail
$ ./check_fail2ban --verbose -p -j ssh -w 1 -c 5 -P /usr/bin/fail2ban-client
DEBUG : fail2ban_client_path: /usr/bin/fail2ban-client
DEBUG : /usr/bin/fail2ban-client exists and is executable
DEBUG : final fail2ban command: /usr/bin/fail2ban-client
DEBUG : warning threshold : 1, critical threshold : 5
DEBUG : it seems the connection with the fail2ban server is ok
CHECK FAIL2BAN ACTIVITY - OK - 0 current banned IP(s) for the specific jail ssh | currentBannedIP=0

# for all the current jails
$ ./check_fail2ban --verbose -p -w 1 -c 5 -P /usr/bin/fail2ban-client
DEBUG : fail2ban_client_path: /usr/bin/fail2ban-client
DEBUG : /usr/bin/fail2ban-client exists and is executable
DEBUG : final fail2ban command: /usr/bin/fail2ban-client
DEBUG : warning threshold : 1, critical threshold : 5
DEBUG : it seems the connection with the fail2ban server is ok
DEBUG : jails list: apache, ssh-ddos, ssh
DEBUG : the jail apache has currently 0 banned IPs
DEBUG : the jail ssh-ddos has currently 0 banned IPs
DEBUG : the jail ssh has currently 0 banned IPs
CHECK FAIL2BAN ACTIVITY - OK - 3 detected jails with 0 current banned IP(s) | currentBannedIP=0