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RHEL-10-200692 RHEL 10 must be configured to prevent unrestricted mail relaying.

DISA STIG library V1R3
All changes in this version
first version loaded CAT II

Maps to CM-7 via CCI-000381

Title

RHEL 10 must be configured to prevent unrestricted mail relaying.

Control

Note: If postfix is not installed, this is not applicable. Verify RHEL 10 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, this is a finding.

Discussion

If unrestricted mail relaying is permitted, unauthorized senders could use this host as a mail relay to send spam or for other unauthorized activity.

Related controls

CCI-000381

Fix

Configure RHEL 10 so that the postfix configuration file restricts client connections to the local network with the following command: $ sudo postconf -e 'smtpd_client_restrictions = permit_mynetworks,reject'