[Monitorix-general] Bug in 3.12.0

[Frank B <fr...@gm...>]

Hello,

Out of the blue my fail2ban.log got flooded with warnings:

===
2020-02-24 09:25:48,283 fail2ban.filter         [466]: INFO
 [wordpress-hard] Found *.*.105.83 - 2020-02-24 09:25:48
2020-02-24 09:25:48,950 fail2ban.actions        [466]: NOTICE
 [wordpress-hard] Ban *.*.105.83
2020-02-24 09:29:01,333 fail2ban.transmitter    [466]: WARNING Command
['status', 'postfix-rbl'] has failed. Received
UnknownJailException('postfix-rbl',)
2020-02-24 09:30:01,904 fail2ban.transmitter    [466]: WARNING Command
['status', 'postfix-rbl'] has failed. Received
UnknownJailException('postfix-rbl',)
2020-02-24 09:30:39,628 fail2ban.actions        [466]: NOTICE  [sshd] Unban
*.*.248.127
2020-02-24 09:31:01,421 fail2ban.transmitter    [466]: WARNING Command
['status', 'postfix-rbl'] has failed. Received
UnknownJailException('postfix-rbl',)
2020-02-24 09:31:45,704 fail2ban.actions        [466]: NOTICE  [sshd] Unban
*.*.88.77
2020-02-24 09:32:01,895 fail2ban.transmitter    [466]: WARNING Command
['status', 'postfix-rbl'] has failed. Received
UnknownJailException('postfix-rbl',)
2020-02-24 09:32:09,741 fail2ban.actions        [466]: NOTICE  [sshd] Unban
*.*.133.188
2020-02-24 09:33:01,246 fail2ban.transmitter    [466]: WARNING Command
['status', 'postfix-rbl'] has failed. Received
UnknownJailException('postfix-rbl',)
2020-02-24 09:34:01,661 fail2ban.transmitter    [466]: WARNING Command
['status', 'postfix-rbl'] has failed. Received
UnknownJailException('postfix-rbl',)
2020-02-24 09:35:01,283 fail2ban.transmitter    [466]: WARNING Command
['status', 'postfix-rbl'] has failed. Received
UnknownJailException('postfix-rbl',)
2020-02-24 09:36:01,671 fail2ban.transmitter    [466]: WARNING Command
['status', 'postfix-rbl'] has failed. Received
UnknownJailException('postfix-rbl',)
2020-02-24 09:37:01,375 fail2ban.transmitter    [466]: WARNING Command
['status', 'postfix-rbl'] has failed. Received
UnknownJailException('postfix-rbl',)
2020-02-24 09:38:02,241 fail2ban.transmitter    [466]: WARNING Command
['status', 'postfix-rbl'] has failed. Received
UnknownJailException('postfix-rbl',)
2020-02-24 09:39:02,118 fail2ban.transmitter    [466]: WARNING Command
['status', 'postfix-rbl'] has failed. Received
UnknownJailException('postfix-rbl',)
2020-02-24 09:40:01,766 fail2ban.transmitter    [466]: WARNING Command
['status', 'postfix-rbl'] has failed. Received
UnknownJailException('postfix-rbl',)
2020-02-24 09:40:34,032 fail2ban.filter         [466]: INFO
 [wordpress-hard] Found *.*.135.88 - 2020-02-24 09:40:33
2020-02-24 09:40:40,313 fail2ban.filter         [466]: INFO
 [wordpress-hard] Found *.*.135.88 - 2020-02-24 09:40:40
2020-02-24 09:40:46,220 fail2ban.filter         [466]: INFO
 [wordpress-hard] Found *.*.135.88 - 2020-02-24 09:40:45
2020-02-24 09:40:46,342 fail2ban.actions        [466]: NOTICE
 [wordpress-hard] Ban *.*.135.88
2020-02-24 09:41:01,277 fail2ban.transmitter    [466]: WARNING Command
['status', 'postfix-rbl'] has failed. Received
UnknownJailException('postfix-rbl',)
2020-02-24 09:41:49,313 fail2ban.filter         [466]: INFO    [postfix]
Found *.*.176.82 - 2020-02-24 09:41:49
2020-02-24 09:41:49,582 fail2ban.filter         [466]: INFO    [postfix]
Found *.*.176.82 - 2020-02-24 09:41:49
2020-02-24 09:42:00,427 fail2ban.actions        [466]: NOTICE
 [wordpress-hard] Unban *.*.132.32
2020-02-24 09:42:01,672 fail2ban.transmitter    [466]: WARNING Command
['status', 'postfix-rbl'] has failed. Received
UnknownJailException('postfix-rbl',)
===

This looked strange to me, since I've disabled the postfix-rbl jail.
Activating this jail and reloading fail2ban stopped the warnings. As far as
I know there were no changes on my system, so I started digging deeper and
found in apt's history.log:

===
Start-Date: 2020-02-24  09:28:55
Commandline: apt upgrade
Upgrade: monitorix:amd64 (3.11.0-izzy1, 3.12.0-izzy1)
End-Date: 2020-02-24  09:28:57
===

Notice the timestamps of the first warning and the upgrade of Monitorix to
3.12.0.

In monitorix.conf [postfix-rbl] was enabled in the fail2ban graph section.
Disabling this and disabling the postfix-rbl jail again (the host of my VPS
has limited the number of IP packet filtering entries, so I have to be very
selective with my jail setup) fixed the situation. As an added "bonus" I
lost the history of my fail2ban graph in Monitorix; all data in the graph
before the upgrade is gone. The other graphs are fine.

Summary: a disabled jail in fail2ban but enabled in the fail2ban graph
section of Monitorix floods fail2ban.log with warnings. I did not try to
reproduce this issue with other jails.

With kind regards,
Frank B.