iptables: block ip address
iptables -A INPUT -s 139.76.64.65 -j DROP
iptables -A INPUT -s 139.76.224.65 -j DROP
iptables -D INPUT -s 139.76.224.65 -j DROP
iptables -A INPUT -s 139.76.64.65 -j DROP
iptables -A INPUT -s 139.76.224.65 -j DROP
iptables -D INPUT -s 139.76.224.65 -j DROP