STIGQter STIGQter: STIG Summary: Tri-Lab Operating System Stack (TOSS) 5 Security Technical Implementation Guide Version: 1 Release: 1 Benchmark Date: 26 Mar 2026:

TOSS 5 must be configured to prevent unrestricted mail relaying.

DISA Rule

SV-282681r1201023_rule

Vulnerability Number

V-282681

Group Title

SRG-OS-000480-GPOS-00227

Rule Version

TOSS-05-000207

Severity

CAT II

CCI(s)

Weight

10

Fix Recommendation

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

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

Check Contents

Verify TOSS 5 is configured to prevent unrestricted mail relaying using 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-282681

Documentable

False

Rule Version

TOSS-05-000207

Severity Override Guidance

Verify TOSS 5 is configured to prevent unrestricted mail relaying using 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

5738