2022. 5. 31. · as root or with sudo: iptables -A INPUT -s 192.168.1.100 -p icmp -j DROP. will block all ping (icmp requests) from a the specified IP. The following to block all ICMP: iptables -A INPUT -p icmp -j DROP. Basically omitting the ip will bock ALL ping requests. to remove the following active firewall rule: iptables -A INPUT -p icmp -j DROP.