DISA STIGS Viewer

Finding ID	Version	Rule ID	IA Controls	Severity
V-271875	OL09-00-006032	SV-271875r1092337_rule		Medium

Description

ICMP redirect messages are used by routers to inform hosts that a more direct route exists for a particular destination. These messages contain information from the system's route table possibly revealing portions of the network topology. The ability to send ICMP redirects is only appropriate for systems acting as routers.

STIG	Date
Oracle Linux 9 Security Technical Implementation Guide	2025-05-08

Check Text (C-75925r1092335_chk)

Verify that OL 9 does not IPv4 ICMP redirect messages. Check the value of the "all send_redirects" variables with the following command: $ sysctl net.ipv4.conf.all.send_redirects net.ipv4.conf.all.send_redirects = 0 If "net.ipv4.conf.all.send_redirects" is not set to "0" and is not documented with the information system security officer (ISSO) as an operational requirement or is missing, this is a finding.

Fix Text (F-75832r1092336_fix)

Configure OL 9 to not allow interfaces to perform IPv4 ICMP redirects. Add or edit the following line in a single system configuration file in the "/etc/sysctl.d/" directory: net.ipv4.conf.all.send_redirects = 0 Load settings from all system configuration files with the following command: $ sudo sysctl --system