Fail2ban

stolen from: https://serverfault.com/questions/841183/how-to-show-all-banned-ip-with-fail2ban

# fail2ban-client has some useful commands.

<fail2ban-client start       # Starts the Fail2ban server and jails.
fail2ban-client reload      # Reloads Fail2ban’s configuration files.
fail2ban-client reload JAIL # Replaces JAIL with the name of a Fail2ban jail; this will reload the jail.
fail2ban-client stop        # Terminates the server.
fail2ban-client status      # Will show the status of the server, and enable jails.
fail2ban-client status JAIL # Will show the status of the jail, including any currently-banned IPs.

See them all at https://www.fail2ban.org/wiki/index.php/Commands

Somebody clever posted this (I don't remember where, not mine) to list all jails in one go:

sudo fail2ban-client status | sed -n 's/,//g;s/.*Jail list://p' | xargs -n1 sudo fail2ban-client status