Postfix Configuration (Chapter 9, Email Servers)

Hi:
The lab 9.1 solution indicates I should
Enable Postfix to listen on all interfaces: # postconf -e "inet_interfaces = all"
but the /etc/posftfix/main.cf and http://www.postfix.org/postconf.5.html#inet_interfaces indicate the default settings is to allow email on all interfaces. Why is this change needed?
Comments
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If I'm not mistaken in the above, a Knowledge Check question #9.4 should also be updated.
0 -
Most distributions set the listener off by default so when installing, if you do not specifically alter the listener it could leave your system exposed to bad actors.
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Thanks for the response. Can you provide an example of a distribution that changes the default setting?
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I checked this on Debian 10, Ubuntu 20.04, and Fedora 34. The Debian install left the
inet_interfaces
setting commented out in the/etc/postfix/main.cf.proto
file. The actual main.cf file that was created during the install was nearly empty. The Debian Administrator's Handbook also provides an examplemain.cf
file withinet_interfaces=all
as the setting.Ubuntu 20.04 LTS and Fedora 34 installed Postfix with
inet_interfaces=all
set in the defaultmain.cf
file.This has been my experience. While the
inet_interfaces=all
setting may be a reasonable precautionary step to take, the Knowledge Check question #9.4 answer appears to be inaccurate.0 -
Yes, you are correct, the default seems to be set to all network interfaces. The lab will get changed to "verify and change if necessary."
Thank you for pointing this out.
Lee0 -
Thanks for resolving this question for me!
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@lee42x said:
Yes, you are correct, the default seems to be set to all network interfaces. The lab will get changed to "verify and change if necessary."Thank you for pointing this out.
LeeThere's still another issue with this lab - it states:
Verify postfix is listening on the network interfaces.
# postconf -d "inet_interfaces"
This led me on a goose chase later when trying to use
postconf -d
to check settings I was changing. The problem is thatpostconf -d
shouldn't be used to verify what postfix is doing, it shows defaults - the correct command to verify what interfaces postfix is configured to listen on ispostfix -p "inet_interfaces"
0 -
Yes you are correct.
postconf -d shows the default values.
postconf -n show values that have been set to a value.On my test machine:
[root@centos ~]# postconf -n inet_interfaces
inet_interfaces = localhost
[root@centos ~]# postconf -d inet_interfaces
inet_interfaces = allLee
0
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