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UBTU-16-030620 - The Ubuntu operating system must be configured to prevent unrestricted mail relaying.

Information

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:

# sudo postconf -e 'smtpd_relay_restrictions = permit_mynetworks, permit_sasl_authenticated, reject'

See Also

https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_CAN_Ubuntu_16-04_LTS_V2R3_STIG.zip

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-6b., CAT|II, CCI|CCI-000366, Rule-ID|SV-215155r610931_rule, STIG-ID|UBTU-16-030620, STIG-Legacy|SV-90571, STIG-Legacy|V-75891, Vuln-ID|V-215155

Plugin: Unix

Control ID: 4fbafd8d59b3bd5f7550cd5a922d5fe0bb6a54f5fadc5673ed9d900865634ee8