I run a gaming server that's occasionally inundated by spammers who evade IP bans by using open proxies.

I'd like to block them using blacklists such as dronebl and abuse.ch. I've found directions as to how to use these blacklists for TCP-wrapped services (such as ssh) through hosts.deny, but the server doesn't use tcp wrapper.

Is there any solution using, say, iptables or UFW that I can use to block all connections on a generic port from an IP on one of these DNSBLs?