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 How to get the DKIM public key from Plesk if DNS is not installed?

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Renan Moreira
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Plesk kb: how-to ABT: Group A

Question

How to get the DKIM public key from Plesk if an external DNS is used and local DNS is not installed?

Answer

Starting from Plesk Obsidian 18.0.35 DKIM public key is shown in the pop-up window on the Mail Settings page of the particular domain.

  1. Log into Plesk

  2. Go to Domains > example.com > Mail Settings > How to configure external DNS:

mceclip0.png

  • For Plesk Version lower than 18.0.35 it's possible to use a manual approach:
For Linux

  1. Connect to the server via SSH

  2. Private keys are located in the corresponding domain directory in /etc/domainkeys/, for example, /etc/domainkeys/**example.com**/default (for selector "default")

  3. To extract a public key from a private, run the following:

    # openssl rsa -in /etc/domainkeys/example.com/default -pubout
    -----BEGIN PUBLIC KEY-----
    MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQC+aOU9Dw2Qedi6qOEcpbGQ3pHV
    I8SonKGNSBBgiImChx6k6I7s1UqeCzaHpKXKLIY4GA601gloVCnnTumZ/5TxnviB
    Hg1a2lsatt/gCj2pl61a+uALM1oRdgPhxPYefloFpi0lau8thV6u9BYTfUgfqIF+
    dvFIVlu0MULsWDDJfwIDAQAB
    -----END PUBLIC KEY-----

    Merge the result of the command above into one string, and add it as a TXT record for the domain on external DNS server:

    default._domainkey.example.com IN TXT "v=DKIM1;k=rsa; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQC+aOU9Dw2Qedi6qOEcpbGQ3pHVI8SonKGNSBBgiImChx6k6I7s1UqeCzaHpKXKLIY4GA601gloVCnnTumZ/5TxnviBHg1a2lsatt/gCj2pl61a+uALM1oRdgPhxPYefloFpi0lau8thV6u9BYTfUgfqIF+dvFIVlu0MULsWDDJfwIDAQAB;"

For Windows

  1. Connect to the server via RDP

  2. In case of MailEnable mail server is used find it's configuration directory:

    reg query "HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Mail Enable\Mail Enable" | findstr "CONFIG"
    Configuration Directory REG_SZ C:\Program Files (x86)\Mail Enable\CONFIG

    and execute below command, do not forget to replace -in path with found one plus add \DKIM\default-example.com.key:

    "%plesk_bin%\openssl" rsa -in "C:\Program Files (x86)\Mail Enable\Config\DKIM\default-example.com.key" -pubout > C:\public.key

    The file C:\public.key will look like:

    -----BEGIN PUBLIC KEY-----
    MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCj/lKsikGILTobyJySVXLe4vK2
    Yvt82Gqk0og/p5XOXhDxxpjUgKig437UucQHwwVrmwFZ0bavMlg3QLQvRb0S94fE
    5jRmikQ9I37v7BZtnxVXXbnrz/GDNLfWlHSugWcf0xY0xV5oi4mhhApwZOYq0SEM
    zLt5kgMkCY50hNPuNQIDAQAB
    -----END PUBLIC KEY-----

    Merge the result into one string and copy the data of the public key file into TXT record for the domain to add it on external DNS server.

    default._domainkey.example.com. TXT v=DKIM1; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCj/lKsikGILTobyJySVXLe4vK2Yvt82Gqk0og/p5XOXhDxxpjUgKig437UucQHwwVrm

Comments

44 comments

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  • Avatar
    Janik R.

    I rewrote the script a little bit so that the keys can now be saved directly in the customer's document root.
    In addition, the script is no longer executed when creating subdomains.

    I've added a little description and installation guide in the readme.

    https://github.com/rabe0577/plesk-dkim-recreate

    I hope I can help you with that.

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  • Avatar
    Pascal Saul

    Is it possible to show the public key in the control panel under "Mail Settings" please. We're not all admins ;)

    Your example is not complete and should be:

    default._domainkey.example.com IN TXT "v=DKIM1;k=rsa;p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQC+aOU9Dw2Qedi6qOEcpbGQ3pHVI8SonKGNSBBgiImChx6k6I7s1UqeCzaHpKXKLIY4GA601gloVCnnTumZ/5TxnviBHg1a2lsatt/gCj2pl61a+uALM1oRdgPhxPYefloFpi0lau8thV6u9BYTfUgfqIF+dvFIVlu0MULsWDDJfwIDAQAB

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  • Avatar
    Jussi Vainionpää

    Just wanted to let everyone know an easy workaround to finding DKIM public record if DNS is hosted somewhere else.

    Just enable DNS for the domain for a few seconds so you can see the DKIM generated in the Plesk DNS management. Copy that to clipboard and disable DNS.

    This DKIM record seemed to work perfectly for me when I copied it to my external DNS.

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  • Avatar
    Anton Maslov

    Hi @IDC,

    This file should not be created manually, it should be created automatically by Plesk when you enable DKIM. Please remove that file and then make sure DKIM is enabled on your server:

    • The option Allow signing outgoing mail is enabled in Tools & Settings > Mail Server Settings
    • The option Use DKIM spam protection system to sign outgoing email messages is enabled in Domain > example.com > Mail Settings
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  • Avatar
    Iain

    The article mentions; "/etc/domainkeys/**example.com**/default (for selector "default")"

    Does this mean it's possible to set a selector name other than 'default'? If so, how?

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  • Avatar
    Harm Jakob Tolsma (Edited )

    Jussi Vainionpää

    You could also edit the script and have it send you the key.

    ##send the key by email
    mail -s "DKIM record for ${NEW_DOMAIN_NAME}" youremail@domain.com < $dkim_rec_path/$dkim_rec_prefix${NEW_DOMAIN_NAME}$dkim_rec_fe

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  • Avatar
    Iain

    Hi Francisco Roman Garcia Rodriguez, previous did that. See custom dkim selector name  :-)

    0
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  • Avatar
    M.Ouattara (Edited )

    Hi All.

    need your help please.

    I got this error "Error, no such file or directory"

    In fact the directory /etc/domainkeys/ do not exit on my dedicated server. however, i have checked on mail setting DMARC, DKIM an SPF on my Plesk 17.8.11.  but directories still unavailable.

    Need your help

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  • Avatar
    lydie_t

    Hi @Alexandr Redikultsev,

    Connecting under root, I am now able to access "default" file (which is the private key), then execute the command indicated by @Bato Tsydenov. This creates the public key.

    Thank you. This helped.

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  • Avatar
    Fabien Galiana

    I did the same process for all my domains on server. and some of them are working and other not ! with same configuration ! this is insane !

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  • Avatar
    Carlos Ivan Castillo Moya

    to see if I understand, when I mark the option "Plesk > Domains > example.com > Mail Settings > Use DKIM spam protection system to sign outgoing email messages" indicates that records are generated in the DNS zone of plesk, right? If the answer is yes, it means that if you use this panel DKIM will work well.

    Now, if I use external DNS I could refer to the DNS zone where the records are using a CNAME record ?

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  • Avatar
    Bato Tsydenov

    Hello Harm Jakob Tolsma

    Thank you for bringing this to our attention.

    I have updated the script so that it is working correctly now.

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  • Avatar
    Taras Ermoshin

    Hello @Cfaessler !

    To do that, it should be possible to call system utilities (like openssl) via API. Unfortunately, it is not possible to do that either with our XML API or REST API.

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  • Avatar
    Adl

    Hi, on my test system seems that script not recognize ${NEW_DOMAIN_NAME} parameter.

    I can only see this in /tmp/dkim_keys, a file called

    "dkim_key_.txt"

    And inside this file only

    "default._domainkey. IN TXT "v=DKIM1;k=rsa; p="

    Thanks a lot.

     

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  • Avatar
    Florent

    Hi,

    Is it possible to change the "default" selector to something else ? ("plesk" for example ;))

    Thx

    0
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  • Avatar
    Nikita Nikushkin

    Hi @M.Ouattara!

    The "/etc/domainkeys/" folder is missing because you have not marked the "Plesk > Domains > example.com > Mail Settings > Use DKIM spam protection system to sign outgoing email messages" checkbox for any domain yet

    Once you mark it for any domain, the "/etc/domainkeys/" folder will be created automatically together with the domain's related folder "/etc/domainkeys/example.com"

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  • Avatar
    Alexandr Redikultsev

    Hi @IDC,

    Make sure that corresponding file /etc/domainkeys/example.com/default exists indeed. Do not forget to replace example.com with the actual domain's name.

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  • Avatar
    IDC

    Error No such file or directory

    # openssl rsa -in /etc/domainkeys/example.com/default -pubout -out public.key
    Error opening Private Key /etc/domainkeys/example.com/default
    139977471330208:error:02001002:system library:fopen:No such file or directory:bss_file.c:402:fopen('/etc/domainkeys/example.com/default','r')
    139977471330208:error:20074002:BIO routines:FILE_CTRL:system lib:bss_file.c:404:
    unable to load Private Key

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  • Avatar
    Alex

    Hi.

    I have following issue:

    I use external DNS service, and I setup DKIM private key as described in a manual on this page. It was working fine with Onyx, but after updating to Obsidian, I now get an error from the backup manager - WARNING: (Mail object 'domain.com') Unable to back up domain keys. Error: Call to a member function getRecordsMatched() on null.

    I have re-issued default key, generated a new pub-key, but still getting the error.

    Any ideas how to fix this issue?

    Thanks

     

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  • Avatar
    Lars Jansen

    Jussi Vainionpää I created an account on this forum, just to thank you!

    0
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  • Avatar
    Harm Jakob Tolsma

    I kept getting errors when verifying DKIM. "OpenSSL wrong tag"
    After some searching I found the reason.
    The script in zip-file seems to use the private key in the output for the record when it is actually the public key that needs to be included.

    ## recreate key:
    openssl rsa -in /etc/domainkeys/$new_domain_name/default -pubout -out public.key  --> Here we create a public key

    ## crop first and last line of keyfile
    sed '1d;$d' /etc/domainkeys/$new_domain_name/default > $tmp_path/$tmp_prefix$new_domain_name$tmp_fe   --> here we trim the private key

    Everything worked as expected after I changed the last line to:
    sed '1d;$d' public.key > $tmp_path/$tmp_prefix$new_domain_name$tmp_fe

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  • Avatar
    Ivan Postnikov

    @Prodesignerch, please, could you give more details about the issue?

    When do you have this error shown? During which step of resolution?

    Also, let us know what OS and Plesk versions do you use?

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  • Avatar
    Anton Maslov

    Currently, Plesk allows using only "default" name. There is a corresponding feature request which you may vote to get this implemented.

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  • Avatar
    Jonathan Burrows (Edited )

    Clicking 'mydomain' >> Mail Settings >> Use DKIM spam protection system to sign outgoing email messages 

     

    Produces the following error.  No domainkeys directory is created and the checkbox remains unticked

    DNS is on external provider

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  • Avatar
    黃彥儒

    Could I change string "default" at "default._domainkey.example.com"?

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  • Avatar
    Alisa Kasyanova

    @Janik R.
    Thank you so much for sharing this! I am sure other Pleskians will find it helpful.

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  • Avatar
    IDC

    Hi @Alexandr Redikultsev,

    Thank you for your response.

    Now,I am created file /etc/domainkeys/example.com/default and re-place exam.com to my domain's name.

    This error tell me "unable to load Private Key"

    # openssl rsa -in /etc/domainkeys/mydomain.com/default -pubout -out public.key
    unable to load Private Key
    140544879454112:error:0906D06C:PEM routines:PEM_read_bio:no start line:pem_lib.c:707:Expecting: ANY PRIVATE KEY

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  • Avatar
    Alexandr Redikultsev

    Also, automatic script should be executed only via Tools & Settings > Event Manager, manual execution of the script via the command line will not work.

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  • Avatar
    Maxim Krasikov (Edited )

    Hello @Carlos Ivan Castillo Moya,

    You are right, when option "Use DKIM spam protection system to sign outgoing email messages" is enabled, the corresponding DKIM record is generated for the domain DNS zone in Plesk.

    Since an external DNS server is used for a domain, the TXT record related to DKIM should be transferred to the external DNS as it is.

    You can find the additional information about DKIM protection here:
    https://support.plesk.com/hc/en-us/articles/115003843813

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  • Avatar
    Just Forgaming

    I stand corrected. I just now see that this is actually from 18.035 and I have 34. My apologies.

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