You can block any IP address which is trying to reach your server by "iptables".

IP Ban:

iptables -A INPUT -s 192.168.2.1 -j DROP

This makes immediately disconnect on IP.

IP Ban Removal:

iptables -X INPUT -s 192.168.2.1 -j DROP

Both cases, you will use IP you would like to block instead of "192.168.2.1"

If you are looking for consultation, fill the Contact Form below.

Know thyself, know thy enemy. A thousand battles, a thousand victories. Sun Tzu