STIGQter: STIG Summary: Cloud Linux AlmaLinux OS 9 Security Technical Implementation Guide Version: 1 Release: 7 Benchmark Date: 01 Jul 2026:

AlmaLinux OS 9 must not send Internet Control Message Protocol (ICMP) redirects.

DISA Rule

SV-269256r1050138_rule

Vulnerability Number

V-269256

Group Title

SRG-OS-000480-GPOS-00227

Rule Version

ALMA-09-019930

Severity

CAT II

CCI(s)

• CCI-000366 - Implement the security configuration settings.

Weight

10

Fix Recommendation

Configure AlmaLinux OS 9 to not allow interfaces to perform ICMP redirects.

Create a numbered *.conf file in /etc/sysctl.d/ with the following content:

net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0
net.ipv4.conf.lo.send_redirects = 0
EOF

The system configuration files need to be reloaded for the changes to take effect. To reload the contents of the files, run the following command:

$ sysctl –system

Check Contents

Verify AlmaLinux OS 9 does not send ICMP redirects.

Check the value of the "send_redirects" variables with the following command:

$ sysctl -a | grep send_redirects

net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0
net.ipv4.conf.enp1s0.send_redirects = 0
net.ipv4.conf.lo.send_redirects = 0

If the returned lines do not all have a value of "0", this is a finding.

Vulnerability Number

V-269256

Documentable

False

Rule Version

ALMA-09-019930

Severity Override Guidance

Verify AlmaLinux OS 9 does not send ICMP redirects.

Check the value of the "send_redirects" variables with the following command:

$ sysctl -a | grep send_redirects

net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0
net.ipv4.conf.enp1s0.send_redirects = 0
net.ipv4.conf.lo.send_redirects = 0

If the returned lines do not all have a value of "0", this is a finding.

Check Content Reference

M

Target Key

5664