The Photon operating system must not respond to IPv4 Internet Control Message Protocol (ICMP) echoes sent to a broadcast address.

Responding to broadcast (ICMP) echoes facilitates network mapping and provides a vector for amplification attacks.

At the command line, run the following command:

# /sbin/sysctl -a --pattern ignore_broadcasts

Expected result:

net.ipv4.icmp_echo_ignore_broadcasts = 1

If the output does not match the expected result, this is a finding.

At the command line, run the following commands:

# sed -i -e "/^net.ipv4.icmp_echo_ignore_broadcasts/d" /etc/sysctl.conf
# echo net.ipv4.icmp_echo_ignore_broadcasts=1>>/etc/sysctl.conf
# /sbin/sysctl --load