OL 9 must not respond to Internet Control Message Protocol (ICMP) echoes sent to a broadcast address.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-271873 | OL09-00-006030 | SV-271873r1092331_rule | CCI-000366 | medium |
| Description | ||||
| Responding to broadcast (ICMP) echoes facilitates network mapping and provides a vector for amplification attacks. Ignoring ICMP echo requests (pings) sent to broadcast or multicast addresses makes the system slightly more difficult to enumerate on the network. | ||||
| STIG | Date | |||
| Oracle Linux 9 Security Technical Implementation Guide | 2025-05-08 | |||
Details
Check Text (C-271873r1092331_chk)
Verify that OL 9 does not respond to ICMP echoes sent to a broadcast address.
Check the value of the "icmp_echo_ignore_broadcasts" variable with the following command:
$ sysctl net.ipv4.icmp_echo_ignore_broadcasts
net.ipv4.icmp_echo_ignore_broadcasts = 1
If the returned line does not have a value of "1", a line is not returned, or the retuned line is commented out, this is a finding.
Fix Text (F-75830r1092330_fix)
Configure OL 9 to not respond to IPv4 ICMP echoes sent to a broadcast address.
Add or edit the following line in a single system configuration file in the "/etc/sysctl.d/" directory:
net.ipv4.icmp_echo_ignore_broadcasts = 1
Load settings from all system configuration files with the following command:
$ sudo sysctl --system