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Mail relaying must be restricted.


Finding ID Version Rule ID IA Controls Severity
V-218009 RHEL-06-000249 SV-218009r505923_rule Medium
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.
Red Hat Enterprise Linux 6 Security Technical Implementation Guide 2020-09-03


Check Text ( C-19490r377042_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-19488r377043_fix)
Edit the file "/etc/postfix/main.cf" to ensure that only the following "inet_interfaces" line appears:

inet_interfaces = localhost