Вот такое в логах:
fail2ban.actions.action: ERROR ipset --create fail2ban-ssh-iptables-ipset4 iphash
iptables -I INPUT -p tcp -m multiport --dports 23 -m set --match-set fail2ban-ssh-iptables-ipset4 src -j REJECT --reject-with icmp-port-unreachable returned 200