Categoria: FreeNas

Blocking ping responses from system can prevent system from hackers to ICMP flood dos attacks. So it can be a best practice for system security but most of online monitoring systems uses ping requests for monitoring system.
Disable Ping using iptables

You can simply block icmp responses directly from firewall in any Linux systems.

# iptables -A INPUT -p icmp --icmp-type echo-request -j DROP

Block Ping with Kernel Parameter

We can also block ping responses from system by directly updating kernel parameters. In this we can block ping responses temporarily or permanently as below.

Block Ping Temporarily

You can block temporarily block ping responses temporarily using following command

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

Block Ping Permanently

In place of blocking ping temporarily, You can block it permanently by adding following parameter in /etc/sysctl.conf configuration file.

net.ipv4.icmp_echo_ignore_all = 1

Now execute following command to apply settings immediately without rebooting system.

# sysctl -p