IPTABLES DROP Rule not working
If iptables DROP rule is not working in server, use a REJECT rule instead.
Even if the rule was added, the incoming traffic was not stopped, I used a REJECT rule instead and it stopped all incoming traffic.
$ iptables -I INPUT -s IP_ADDRESS -j REJECT
$ service iptables save
$ service iptables restart
After saving and restarting iptables service, the connections from IP address will be dropped / rejected from the server.