DNS/SPF
SPF-DNS - SPF + DK + DKIM with Postfix
Beschreibung
Shows up a detailed process on how to set up SPF + DK + DKIM with Postfix in Plesk 11.5 on Debian Wheezy, step by step, and how to test to make sure everything is working correctly
I leased a dedicated server from Hetzner, and I got the Plesk option, for administration, so I don’t have to bother with administration, but turns out I’m not so lucky, I’ve ran into a lot of issues with using Plesk, so I had to do my own fixes.
So let’s take a look at how we can integrate SPF + DK + DKIM with Postfix in Plesk 11.5 on Debian Wheezy.
First things, first, if you are using QMail switch to Postfix, to install Postfix you can either use the GUI, or you can do it from a console.
Here is how to do it from the console.
/usr/local/psa/admin/sbin/autoinstaller --select-release-current --install-component postfix
SPF
Let’s open the DNS Template, you will see there that, there is an entry for SPF
v=spf1 +a +mx -all
This means the SPF is enabled on our domain.
Let’s modify it a little bit to be better, if you are gonna host multiple domains from your server, then you should probably modify it too.
v=spf1 +a +mx +ip4:<ip.mail> ?all* <ip.mail> - Is the IP of the mail server that is responsible for sending the mails, it is automatically filled in when you apply the zones
After you do this modification you should apply it
So now my configuration looks like this:
Now let’s check with dig if the SPF is OK.
dig myserverplace.de TXT @ns1.myserverplace.de
You will see in the Answer section I have the following entry
myserverplace.de. 600 IN TXT "v=spf1 +a +mx +ip4:144.76.163.46 ?all"
So everything is ok, next onto DomainKeys
DomainKeys
First let’s activate DomainKeys, take a look at the screenshot, and compare my options with yours.
Ok, now that this has been enabled, let’s go and enable for the domain in question, if it was already checked, uncheck it press OK, and then check it again and press OK, this is so it will regenerate the DomainKeys data in the DNS zone, as I’ve had some problems with the data not present in the DNS zone file
OK, now let’s see if the correct data is there, usually it takes a long time for DNS to propagate between 24-48h, there is a simple way to test if the data is there, by querying the Nameserver that hosts your DNS zone, in my case I host my own Nameserver
dig _domainkey.myserverplace.de TXT @ns1.myserverplace.de
You will see in the Answer section I have the following entry
_domainkey.myserverplace.de. 600 IN TXT "o=-"
Now let’s see if the DomainKey is there too
dig default._domainkey.myserverplace.de TXT @ns1.myserverplace.de
In the Answer section you should see something like
default._domainkey.myserverplace.de. 600 IN TXT "p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDAruBNqdsSCKBLwMrFNNKH8z0e7zmlAic7iRoJsDDJK3IlnW8j6G/T6a93m+jqYc6R38MBAZbeSv2LQJ0SepJEsr4Iqk41WFXPBKnyXReO1RXPW5/YnRe6dpJMEqsmPpl2TjInY7ve/6VCiVDOHn9RRrdB+x7CGeK2crgqSZVlFwIDAQAB\;"
As you can see everything is in place now for DomainKeys to work, now let’s continue on to DKIM
Postfix
Now let’s see what we need to do to configure Postfix to use OpenDKIM.
Execute the following command to see the milters configured
cat /etc/postfix/main.cf | grep "milters" smtpd_milters = , inet:127.0.0.1:12768 non_smtpd_milters = , inet:127.0.0.1:12768
You can see that we have additional milters we need to put, this one is from the process psa-pc-remote, and it’s part of Plesk
Open /etc/postfix/main.cf with your favorite editor, and add the following to the end of the file
# OpenDKIM milter_default_action = accept milter_protocol = 6 smtpd_milters = , inet:127.0.0.1:8891, inet:127.0.0.1:12768 non_smtpd_milters = $smtpd_milters
As you can see we added the OpenDKIM milter too, and milter_protocol is set to 6, this is important, if it’s not set to 6, the psa-pc-remote process will segfault like so,
psa-pc-remote[18523]: segfault at 0 ip 00007fa5be18c034 sp 00007fa5bccffd30 error 4 in libc-2.13.so[7fa5be123000+180000]
And your messages won’t be signed with DomainKey, only with DKIM
service postfix restart
Testing
There is an easy way to test if everything is correct, create an email account if you haven’t already and send a test mail to the following recepients, and the results are cut down because the text is too big* check-auth@verifier.port25.com
========================================================== Summary of Results ========================================================== SPF check: pass DomainKeys check: pass DKIM check: pass Sender-ID check: pass SpamAssassin check: ham* AAAA3QcKCQwA@appmaildev.com ============================================================ SPF result: Pass ============================================================ Domain: myserverplace.de IP: 144.76.163.46 SPF Record: myserverplace.de IN TXT = "v=spf1 +a +mx 144.76.163.46 ?all" ============================================================ DomainKey result: pass ============================================================ Signed by: admin@myserverplace.de PublicKey: default._domainkey.myserverplace.de IN TXT = "p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDAruBNqdsSCKBLwMrFNNKH8z0e7zmlAic7iRoJsDDJK3IlnW8j6G/T6a93m+jqYc6R38MBAZbeSv2LQJ0SepJEsr4Iqk41WFXPBKnyXReO1RXPW5/YnRe6dpJMEqsmPpl2TjInY7ve/6VCiVDOHn9RRrdB+x7CGeK2crgqSZVlFwIDAQAB;" ============================================================ DKIM result: pass ============================================================ Signed by: admin@myserverplace.de Expected Body Hash: frcCV1k9oG9oKj3dpUqdJg1PxRT2RSN/XKdLCPjaYaY= PublicKey: mail._domainkey.myserverplace.de IN TXT = "v=DKIM1; k=rsa; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDMziMcgPTWK0kSUKxrgHHzEiWxNkZ2/M0Ugyr/8H9WtoCsJUM+Bc1C9VwqJ6yjTidecDrX7aL0lFZ9Mylku/wtSiPw6KLxMg2LG2vrMzlPTB2lmJNmg/EOu3KPC8BtAuOhXfwVH/ttQbzdKJKWqiCJn7jhF5oqEKnOCORxOQXKIwIDAQAB;"
Logs
You can check the following locations to see if there are errors
- /var/log/mail.err
- /var/log/mail.warn
- /var/log/mail.info
- /var/log/syslog
Note
Make sure you enable testing mode for DKIM if you plan to test, you can also cut down the EXPIRY time so the results propagate faster, so to enable testing mode set the key _domainkey to t=y; o=-
