bouncers

Bouncers are standalone software pieces in charge of acting upon blocked IPs.

They can either be within the applicative stack, or work out of band :

nginx bouncer will check every unknown IP against the database before letting go through or serving a 403 to the user, while a netfilter bouncer will simply "add" malevolent IPs to nftables/ipset set of blacklisted IPs.

You can explore available bouncers on the hub, and find below a few of the "main" bouncers.