How to Permanently Disable Ping Replies on Linux Systems

Permanent Ping Disable

First verify whether the system currently allows ping replies:

cat /proc/sys/net/ipv4/icmp_echo_ignore_all
0

In this output, 0 means ping is allowed, while 1 would block it.

Edit the /etc/sysctl.conf file and add the following line to block ping permanently: net.ipv4.icmp_echo_ignore_all = 1 Apply the new configuration without rebooting:

sysctl -p
... net.ipv4.icmp_echo_ignore_all = 1

Test the result from another machine; the ping should fail with 100% packet loss:

ping 8.40.7.17
PING 8.40.7.17 (8.40.7.17) 56(84) bytes of data.
^C
--- 8.40.7.17 ping statistics ---
8 packets transmitted, 0 received, 100% packet loss, time 191ms

Temporary Ping Disable (effective until reboot)

Check the current setting (normally 0):

cat /proc/sys/net/ipv4/icmp_echo_ignore_all
0

Set the value temporarily using sysctl -w:

sysctl -w net.ipv4.icmp_echo_ignore_all=1
net.ipv4.icmp_echo_ignore_all = 1

Confirm the change took effect:

cat /proc/sys/net/ipv4/icmp_echo_ignore_all
1

Another Temporary Method

Write directly to the proc file to disable ping until the next reboot:

echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_all