Many malicious attacks begin with a ping scan. Disabling ICMP echo requests prevents your system’s discovery with a ping.

Disable ICMP echo responses temporarily

You can temporarily disable the ICMP using the following method but this setting will be erased after the reboot.

root@lifelinux:~# echo 1 >  /proc/sys/net/ipv4/icmp_echo_ignore_all

Also, to enable the ICMP echo responses back, type the following command:

root@lifelinux:~# echo 0 >  /proc/sys/net/ipv4/icmp_echo_ignore_all

Disable ICMP echo responses permanently

You can permanently disable the ICMP echo reponses using the following method:
Edit the sysctl.conf file:

root@lifelinux:~# vi /etc/sysctl.conf

And add the following line:

net.ipv4.icmp_echo_ignore_all = 1

After that, execute sysctl -p to enforce this setting immediately:

root@lifelinux:~# sysctl -p

The above command loads the sysctl settings from the sysctl.conf.

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