Alle gebannten IP's und in welchem jail herrauszufinden ist bei fail2ban ziemlich aufwending ud unübersichtlich.
Deshalb hier ein paar Möglichkeiten

fail2ban-client status | grep "Jail list:" | sed "s/ //g" | awk '{split($2,a,",");for(i in a) system("fail2ban-client status " a[i])}' | grep "Status\|IP list"

Fail2ban nutzt die Daenbank sqlite3.
Diese lässt sich natürlich abfragen:
 

sqlite3 /var/lib/fail2ban/fail2ban.sqlite3 \ 
"select datetime(timeofban, 'unixepoch', 'localtime') as startofban, 
datetime(timeofban + bantime, 'unixepoch', 'localtime') as endofban, 
ip, jail, bantime, bancount, data from bips 
where endofban > datetime('now', 'localtime') 
order by jail, endofban 
limit 10"

Show all IP address and its jail:

sqlite3 /var/lib/fail2ban/fail2ban.sqlite3 "select ip,jail from bips"

Show all unique IP address:

sqlite3 /var/lib/fail2ban/fail2ban.sqlite3 "select distinct ip from bips"

Show all unique IP address in sshd jail:

sqlite3 /var/lib/fail2ban/fail2ban.sqlite3 "select distinct ip from bips where jail='sshd'"

Show top 20 most banned IP address in all jails:

sqlite3 /var/lib/fail2ban/fail2ban.sqlite3 "select jail,ip,count(*) as count from bips group by ip order by count desc limit 20"