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Mail relaying must be restricted.


Finding ID Version Rule ID IA Controls Severity
V-89641 VRAU-SL-000555 SV-100291r1_rule Medium
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.
VMware vRealize Automation 7.x SLES Security Technical Implementation Guide 2018-10-12


Check Text ( C-89333r1_chk )
Determine if Sendmail only binds to loopback addresses by examining the "DaemonPortOptions" configuration options.

# grep -i "O DaemonPortOptions" /etc/sendmail.cf

If there are uncommented DaemonPortOptions lines, and all such lines specify system loopback addresses, this is not a finding.

Otherwise, determine if Sendmail is configured to allow open relay operation.

# grep -i promiscuous_relay /etc/mail/sendmail.mc

If the promiscuous relay feature is enabled, this is a finding.
Fix Text (F-96383r1_fix)
If the SLES for vRealize does not need to receive mail from external hosts, add one or more "DaemonPortOptions" lines referencing system loopback addresses (such as "O DaemonPortOptions=Addr=,Port=smtp,Name=MTA") and remove lines containing non-loopback addresses.

# sed -i "s/O DaemonPortOptions=Name=MTA/O DaemonPortOptions=Addr=,Port=smtp,Name=MTA/" /etc/sendmail.cf

Restart the sendmail service:

# service sendmail restart