STIGQter: STIG Summary: Oracle Linux 9 Security Technical Implementation Guide Version: 1 Release: 6 Benchmark Date: 01 Jul 2026:

OL 9 must be configured to prevent unrestricted mail relaying.

DISA Rule

SV-271763r1092001_rule

Vulnerability Number

V-271763

Group Title

SRG-OS-000480-GPOS-00227

Rule Version

OL09-00-002425

Severity

CAT II

CCI(s)

• CCI-000366 - Implement the security configuration settings.

Weight

10

Fix Recommendation

Modify the postfix configuration file to restrict client connections to the local network with the following command:

$ sudo postconf -e 'smtpd_client_restrictions = permit_mynetworks,reject'

Check Contents

Note: If postfix is not installed, this requirement is Not Applicable.

Verify that OL 9 is configured to prevent unrestricted mail relaying with the following command:

$ postconf -n smtpd_client_restrictions
smtpd_client_restrictions = permit_mynetworks,reject

If the "smtpd_client_restrictions" parameter contains any entries other than "permit_mynetworks" and "reject", and the additional entries have not been documented with the information system security officer (ISSO), this is a finding.

Vulnerability Number

V-271763

Documentable

False

Rule Version

OL09-00-002425

Severity Override Guidance

Note: If postfix is not installed, this requirement is Not Applicable.

Verify that OL 9 is configured to prevent unrestricted mail relaying with the following command:

$ postconf -n smtpd_client_restrictions
smtpd_client_restrictions = permit_mynetworks,reject

If the "smtpd_client_restrictions" parameter contains any entries other than "permit_mynetworks" and "reject", and the additional entries have not been documented with the information system security officer (ISSO), this is a finding.

Check Content Reference

M

Target Key

5680