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

RHEL 9 must not enable IPv4 packet forwarding unless the system is a router.

DISA Rule

SV-257970r1155751_rule

Vulnerability Number

V-257970

Group Title

SRG-OS-000480-GPOS-00227

Rule Version

RHEL-09-253075

Severity

CAT II

CCI(s)

Weight

10

Fix Recommendation

Configure RHEL 9 to not allow IPv4 packet forwarding, unless the system is a router.

Create a configuration file if it does not already exist:

$ sudo vi /etc/sysctl.d/ipv4_forwarding.conf

Add the following line to the file:
net.ipv4.conf.all.forwarding = 0

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

$ sudo sysctl --system

Check Contents

Verify RHEL 9 is not performing IPv4 packet forwarding unless the system is a router.

Check that "net.ipv4.conf.all.forwarding" is disabled using the following command:

$ sudo sysctl net.ipv4.conf.all.forwarding
net.ipv4.conf.all.forwarding = 0

If "net.ipv4.conf.all.forwarding" 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.

Vulnerability Number

V-257970

Documentable

False

Rule Version

RHEL-09-253075

Severity Override Guidance

Verify RHEL 9 is not performing IPv4 packet forwarding unless the system is a router.

Check that "net.ipv4.conf.all.forwarding" is disabled using the following command:

$ sudo sysctl net.ipv4.conf.all.forwarding
net.ipv4.conf.all.forwarding = 0

If "net.ipv4.conf.all.forwarding" 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.

Check Content Reference

M

Target Key

5551