Is it possible to block ip on the server like this?

Question

iptables

Hello.
In general, I keep a proxy server on the VDS, a public one, they are used by all and sundry. Why such a proxy - do not ask questions.
Here the hoster sent a new abuse, there is spam, someone registers many times or ddos, did not read in general, from my server. And the IP and port (443) of the server are indicated, to which I kind of do nasty things.
So here's the question.
If I block this IP in iptables, will they not be able to send spam (or something else) to this IP through my proxy? Or will it still be possible to connect to the IP from which the abuse is?

Answer 1

I think it's a fight with windmills. Today one complains, tomorrow another. There will be problems from the very essence of the service.
And then all of a sudden some kind of mask show will come to visit.

Answer 2

Запретите проксирование всего, кроме HTTP-трафика: порты TCP: 80-82 и проверяйте входящие запросы: кривые - блокируйте и будет счастье.