STIGQter: STIG Summary: Red Hat Enterprise Linux 9 Security Technical Implementation Guide Version: 2 Release: 9 Benchmark Date: 01 Jul 2026:

RHEL 9 must prevent IPv4 Internet Control Message Protocol (ICMP) redirect messages from being accepted.

DISA Rule

SV-257963r1155736_rule

Vulnerability Number

V-257963

Group Title

SRG-OS-000480-GPOS-00227

Rule Version

RHEL-09-253040

Severity

CAT II

CCI(s)

• CCI-000366 - Implement the security configuration settings.

Weight

10

Fix Recommendation

Configure RHEL 9 to prevent IPv4 ICMP redirect messages from being accepted.

Create a configuration file if it does not already exist:

$ sudo vi /etc/sysctl.d/99-ipv4_accept_redirects.conf

Add the following line to the file:
net.ipv4.conf.default.accept_redirects = 0

Reload settings from all system configuration files with the following command:

$ sudo sysctl --system

Check Contents

Verify RHEL 9 will not accept IPv4 ICMP redirect messages.

Check the value of the default "accept_redirects" variable with the following command:

$ sudo sysctl net.ipv4.conf.default.accept_redirects
net.ipv4.conf.default.accept_redirects = 0

If "net.ipv4.conf.default.accept_redirects" is not set to "0" or is missing, this is a finding.

Vulnerability Number

V-257963

Documentable

False

Rule Version

RHEL-09-253040

Severity Override Guidance

Verify RHEL 9 will not accept IPv4 ICMP redirect messages.

Check the value of the default "accept_redirects" variable with the following command:

$ sudo sysctl net.ipv4.conf.default.accept_redirects
net.ipv4.conf.default.accept_redirects = 0

If "net.ipv4.conf.default.accept_redirects" is not set to "0" or is missing, this is a finding.

Check Content Reference

M

Target Key

5551