I just expanded the existing fail2ban config on the commonly used default ports such as 22, 21 Etc, any requests on those ports get sent into purgatory, so the ip gets blacklisted any connections from it hangs until it times out. It's a super basic setup iptables logs whenever a request is not in the current firewall (last rule in the chain) and then fail2ban reads the log and handles the block. I don't count it as part of the normal setup because they're isolated Because the actual ports the service is on still have the normal rule set but the default port numbers are just an instant if there's activity on it you're gone