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

AlmaLinux OS 9 firewall must employ a deny-all, allow-by-exception policy for allowing connections to other systems.

DISA Rule

SV-269246r1050780_rule

Vulnerability Number

V-269246

Group Title

SRG-OS-000480-GPOS-00227

Rule Version

ALMA-09-018830

Severity

CAT II

CCI(s)

CCI-000366 - Implement the security configuration settings.

Weight

Fix Recommendation

Configure the "firewalld" daemon to employ a deny-all, allow-by-exception.

Start by adding the exceptions that are required for mission functionality to the "drop" zone. If SSH access on port 22 is needed for example, run the following command:

$ firewall-cmd --permanent --add-service=ssh --zone=drop

Set the default zone to the "drop" zone:

$ firewall-cmd --set-default-zone=drop

Note: This is a runtime and a permanent change.

Add any interfaces to the newly modified "drop" zone:

$ firewall-cmd --permanent --zone=drop --change-interface=enp1s0

Reload the firewall rules for changes to take effect:

$ firewall-cmd --reload

Check zones and interfaces:

$ firewall-cmd --get-active-zones

drop
interfaces: enp1s0

Check new default zone's target is set to "DROP":

$ firewall-cmd --permanent --info-zone=drop | grep target

target: DROP

The same outcome is achieved by creating a new zone, for example:

$ firewall-cmd --permanent --new-zone=stig
$ firewall-cmd --reload
$ firewall-cmd --permanent --change-interface=enp1s0 --zone=stig
$ firewall-cmd --permanent --add-service=ssh --zone=stig
$ firewall-cmd --permanent --set-target=DROP --zone=stig
$ firewall-cmd --set-default-zone=stig

Check Contents

Verify the AlmaLinux OS 9 "firewalld" is configured to employ a deny-all, allow-by-exception policy for allowing connections to other systems.

First ensure firewalld is running:

$ firewall-cmd --state

running

Next, get the active zones:

$ firewall-cmd --get-active-zones

public
interfaces: enp1s0

Check the target of the zones returned from the previous command:

$ firewall-cmd --info-zone=public | grep target

target: DROP

Check the runtime and permanent rules match:

$ firewall-cmd --permanent --info-zone=public | grep target

target: DROP

If no zones are active on the AlmaLinux OS 9 interfaces or if runtime and permanent targets are set to a different option other than "DROP", this is a finding.

Vulnerability Number

V-269246

Documentable

False

Rule Version

ALMA-09-018830

Severity Override Guidance

Check Content Reference

Target Key

5664