[27759]: ERROR Failed to execute ban jail 'sshd' action in fail2ban log

On my Debian 8 server, I see lots of this error in fail2ban log.

 [27759]: ERROR   Failed to execute ban jail 'sshd' action 'iptables-multiport' info 'ActionInfo({'ip': '1.1.2.2', 'fam
ily': 'inet4', 'ip-rev': '2.2.1.1.', 'ip-host': '210994.cloudwaysapps.com', 'fid': '1.1.2.2', 'failures': 3, 'time': 1547974803.0, 'matches': 'Jan 20 04:00:01
 chat sshd[1326]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=1.1.2.2 \nJan 20 04:00:03 chat sshd[1326]: Failed password f
or invalid user guest from 1.1.2.2 port 40633 ssh2', 'restored': 0, 'F-*': {'matches': ['Jan 20 04:00:01 chat sshd[1326]: pam_unix(sshd:auth): authentication failure;
 logname= uid=0 euid=0 tty=ssh ruser= rhost=1.1.2.2 ', 'Jan 20 04:00:03 chat sshd[1326]: Failed password for invalid user guest from 1.1.2.2 port 40633 ssh2']
, 'failures': 3, 'mlfid': ' chat sshd[1326]: ', 'user': 'guest', 'ip4': '1.1.2.2'}, 'ipmatches': 'Jan 20 04:00:01 chat sshd[1326]: pam_unix(sshd:auth): authentication
 failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=1.1.2.2 \nJan 20 04:00:03 chat sshd[1326]: Failed password for invalid user guest from 1.1.2.2 port 40633
 ssh2', 'ipjailmatches': 'Jan 20 04:00:01 chat sshd[1326]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=1.1.2.2 \nJan 20 04
:00:03 chat sshd[1326]: Failed password for invalid user guest from 1.1.2.2 port 40633 ssh2', 'ipfailures': 3, 'ipjailfailures': 3})': Error banning 1.1.2.2
2019-01-20 04:01:24,018 fail2ban.actions  

I'm wondering what this error mean and how to fix it?

Solution 1:

possible reason: duplicate IP table chains (you need to check your roles), if this is the issue you can fix it be doing the following:

• stop f2b
• restart iptables
• backup your config-dir (/etc/fail2ban), just to compare (don't use it hereafter)
• uninstall f2b
• remove your config-dir (/etc/fail2ban), install f2b
• create your own fail2ban.local, jail.local and make there the changes, enable jails etc.
  • start f2b