UCF STIG Viewer Logo
Changes are coming to https://stigviewer.com. Take our survey to help us understand your usage and how we can better serve you in the future.
Take Survey

The Oracle Linux operating system must not allow interfaces to perform Internet Protocol version 4 (IPv4) Internet Control Message Protocol (ICMP) redirects by default.


Overview

Finding ID Version Rule ID IA Controls Severity
V-221880 OL07-00-040650 SV-221880r880657_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.
STIG Date
Oracle Linux 7 Security Technical Implementation Guide 2023-06-02

Details

Check Text ( C-23595r880655_chk )
Verify the system does not allow interfaces to perform IPv4 ICMP redirects by default.

# grep -r net.ipv4.conf.default.send_redirects /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.conf.default.send_redirects" 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 "0", this is a finding.

Check that the operating system implements the "default send_redirects" variables with the following command:

# /sbin/sysctl -a | grep net.ipv4.conf.default.send_redirects
net.ipv4.conf.default.send_redirects = 0

If the returned line does not have a value of "0", this is a finding.

If conflicting results are returned, this is a finding.
Fix Text (F-23584r880656_fix)
Configure the system not to allow interfaces to perform IPv4 ICMP redirects by default.

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.conf.default.send_redirects = 0

Issue the following command to make the changes take effect:

# sysctl --system