blocked ips ======================== 45.125.65.88 141.98.10.37 193.169.254.67 185.234.217.188 45.125.65.65 141.98.80.15 45.125.65.63 185.234.217.188 45.125.66.183 185.53.91.24 185.53.91.24 sudo iptables -A INPUT -s 45.125.65.0/24 -j DROP sudo iptables -A INPUT -s 141.98.10.0/24 -j DROP sudo iptables -A INPUT -s 193.169.254.0/24 -j DROP sudo iptables -A INPUT -s 185.234.217.0/24 -j DROP sudo iptables -A INPUT -s 185.36.81.0/24 -j DROP sudo iptables -A INPUT -s 141.98.80.0/24 -j DROP sudo iptables -A INPUT -s 45.125.65.0/24 -j DROP sudo iptables -A INPUT -s 185.234.217.188 -j DROP sudo iptables -A INPUT -s 45.125.66.0/24 -j DROP sudo iptables -A INPUT -s 185.53.91.24 -j DROP https://help.ubuntu.com/community/PortKnocking ``` To block 116.10.191.* addresses: $ sudo iptables -A INPUT -s 116.10.191.0/24 -j DROP To block 116.10.*.* addresses: $ sudo iptables -A INPUT -s 116.10.0.0/16 -j DROP To block 116.*.*.* addresses: $ sudo iptables -A INPUT -s 116.0.0.0/8 -j DROP But be careful what you block using this method. You don't want to prevent legitmate traffic from reaching the host. edit: as pointed out, iptables evaluates rules in sequential order. Rules higher in the ruleset are applied before rules lower in the ruleset. So if there's a rule higher in your ruleset that allows said traffic, then appending (iptables -A) the DROP rule will not produce the intended blocking result. In this case, insert (iptables -I) the rule either: as the first rule sudo iptables -I ... or before the allow rule sudo iptables --line-numbers -vnL say that shows rule number 3 allows ssh traffic and you want to block ssh for an ip range. -I takes an argument of an integer that's the location in your ruleset you want the new rule to be inserted iptables -I 2 ... ckiGO99l ```