Some system administrators often block ICMP messages to their servers in order to hide the Linux boxes to outside world on rough networks or to prevent some kind of IP flooding and denial of service attacks. The most simple method to block ping command on Linux systems is by adding an iptables rule, as shown in the below example. Iptables is a part of Linux kernel netfilter and, usually, is installed by default in most Linux environments. # iptables -A INPUT --proto icmp -j DROP # iptables -L -n -v [List Iptables Rules] Another general method of blocking ICMP messages in your Linux system is to add the below kernel variable that will drop all ping packets. # echo “1” > /proc/sys/net/ipv4/icmp_echo_ignore_all In order to make the above rule permanent, append following line to /etc/sysctl.conf file and, subsequently, apply the rule with sysctl command. # echo “net.ipv...
