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2.1.34 Ensure the operating system is configured to prevent unrestricted mail relaying

Information

The operating system must be configured to prevent unrestricted mail relaying.

If unrestricted mail relaying is permitted, unauthorized senders could use this host as a mail relay for the purpose of sending spam or other unauthorized activity.

Solution

If "postfix" is installed, modify the "/etc/postfix/main.cf" file to restrict client connections to the local network with the following command:

# postconf -e 'smtpd_client_restrictions = permit_mynetworks,reject'

See Also

https://workbench.cisecurity.org/benchmarks/19886

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-6, 800-53|CM-6b., 800-53|CM-7, CAT|II, CSCv7|9.2, Rule-ID|SV-230550r627750_rule, STIG-ID|RHEL-08-040290, Vuln-ID|V-230550

Plugin: Unix

Control ID: 59ef451596e48e689fdd56f468fd4fa1673620a99b31516e4dbd46070961b007