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Mail relaying must be restricted.


Overview

Finding ID Version Rule ID IA Controls Severity
V-208930 OL6-00-000249 SV-208930r793716_rule Medium
Description
This ensures "postfix" accepts mail messages (such as cron job reports) from the local system only, and not from the network, which protects it from network attack.
STIG Date
Oracle Linux 6 Security Technical Implementation Guide 2021-12-03

Details

Check Text ( C-9183r357770_chk )
If the system is an authorized mail relay host, this is not applicable.

Run the following command to ensure postfix accepts mail messages from only the local system:

$ grep inet_interfaces /etc/postfix/main.cf

If properly configured, the output should show only "localhost".
If it does not, this is a finding.
Fix Text (F-9183r357771_fix)
Edit the file "/etc/postfix/main.cf" to ensure that only the following "inet_interfaces" line appears:

inet_interfaces = localhost