The Oracle Linux operating system must not respond to Internet Protocol version 4 (IPv4) Internet Control Message Protocol (ICMP) echoes sent to a broadcast address.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-221877 | OL07-00-040630 | SV-221877r991589_rule | CCI-000366 | medium |
| Description | ||||
| Responding to broadcast (ICMP) echoes facilitates network mapping and provides a vector for amplification attacks. | ||||
| STIG | Date | |||
| Oracle Linux 7 Security Technical Implementation Guide | 2025-05-08 | |||
Details
Check Text (C-221877r991589_chk)
Verify the system does not respond to IPv4 ICMP echoes sent to a broadcast address.
# grep -r net.ipv4.icmp_echo_ignore_broadcasts /run/sysctl.d/* /etc/sysctl.d/* /usr/local/lib/sysctl.d/* /usr/lib/sysctl.d/* /lib/sysctl.d/* /etc/sysctl.conf 2> /dev/null
If "net.ipv4.icmp_echo_ignore_broadcasts" is not configured in the /etc/sysctl.conf file or in any of the other sysctl.d directories, is commented out, or does not have a value of "1", this is a finding.
Check that the operating system implements the "icmp_echo_ignore_broadcasts" variable with the following command:
# /sbin/sysctl -a | grep net.ipv4.icmp_echo_ignore_broadcasts
net.ipv4.icmp_echo_ignore_broadcasts = 1
If the returned line does not have a value of "1", this is a finding.
If conflicting results are returned, this is a finding.
Fix Text (F-23581r880647_fix)
Set the system to the required kernel parameter by adding the following line to "/etc/sysctl.conf" or a configuration file in the /etc/sysctl.d/ directory (or modify the line to have the required value):
net.ipv4.icmp_echo_ignore_broadcasts = 1
Issue the following command to make the changes take effect:
# sysctl --system