DKIM: Difference between revisions

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= DomainKeys Identified Mail =
'''DomainKeys Identified Mail'''


== Links ==


= Links =
[https://dkimvalidator.com/ DKIMvalidator]
*[http://dkimcore.org/tools/keycheck.html dkim check]  
*[http://dkimcore.org/tools/keycheck.html dkim check]  
*[https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-dkim-with-postfix-on-debian-wheezy DKIM and postfix]  
*[https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-dkim-with-postfix-on-debian-wheezy DKIM and postfix]  
*[https://help.ubuntu.com/community/Postfix/dkim-milter https://help.ubuntu.com/community/Postfix/dkim-milter] Postfix and dkim-milter]  
*[https://help.ubuntu.com/community/Postfix/dkim-milter Postfix and dkim-milter]  
*[http://dkim.org/ DKIM Homepage]
*[https://www.samlogic.net/articles/dkim--cname-or-txt.htm DKIM with CNAME or TXT]
*[http://www.opendkim.org/opendkim-README http://www.opendkim.org/opendkim-README]  
*[http://www.sendmail.com/sm/wp/dkim// About DKIM]  
*[http://www.sendmail.com/sm/wp/dkim// About DKIM]  
*[[DKIM_with_Sendmail|DKIM with Sendmail]]  
*[[DKIM_with_Sendmail|DKIM with Sendmail]]  
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*[http://www.myiptest.com/staticpages/index.php/DomainKeys-DKIM-SPF-Validator-test http://www.myiptest.com/staticpages/index.php/DomainKeys-DKIM-SPF-Validator-test]  
*[http://www.myiptest.com/staticpages/index.php/DomainKeys-DKIM-SPF-Validator-test http://www.myiptest.com/staticpages/index.php/DomainKeys-DKIM-SPF-Validator-test]  
*[https://www.linode.com/docs/email/postfix/configure-spf-and-dkim-in-postfix-on-debian-9/ SPF and DKIM on Debian]  
*[https://www.linode.com/docs/email/postfix/configure-spf-and-dkim-in-postfix-on-debian-9/ SPF and DKIM on Debian]  
*[https://tweenpath.net/opendkim-postfix-smtp-relay-server-on-debian-7/  DKIM on relay server]
*[[OpenDKIM]]


 
=HOWTO=
==Check if keys match==
dig myselector._domainkey.example.com txt


and save the bit from "p=" to '''public.key.b64'''
openssl enc -base64 -d -in public.key.b64 -out public.key
openssl rsa -pubin -inform DER -in public.key -noout -modulus
and compare the shown modulus with
openssl rsa -in private.key -noout -modulus


= OpenDKIM Howto =
They should be identical
On Ubuntu you might have to create:
mkdir -p /etc/opendkim/keys
chown -R opendkim.opendkim /etc/opendkim
chmod go-rw /etc/opendkim/keys
 
Then
cd /etc/opendkim/keys
 
The 'selector' you choose here does not have to be the actual selector used in DNS. It is just the name used for storing the .txt and .private files
 
opendkim-genkey -s somename -d domain.name
 
Make sure the key ends up in /etc/opendkim/keys and is readable for user opendkim, so
chown -R opendkim.opendkim /etc/opendkim/keys
 
== SigningTable ==
 
#somename is the first field in Keytable
 
*@domain.name somename
 
== KeyTable ==
 
Here the name of the selector (the part before ._domainkey) is the one you publish in dns
 
somename domain.name:selectorname:/path/to/somename.private
 
==Configuration file /etc/opendkim.conf==
Mode    s
KeyTable        /etc/opendkim/KeyTable
SigningTable    refile:/etc/opendkim/SigningTable
 
 
== Postfix ==
 
In /etc/postfix/main.cf:
 
 
 
milter_protocol = 2
milter_default_action = accept
smtpd_milters = inet:localhost:8891
non_smtpd_milters = inet:localhost:8891
 
 
 
= Checking =
 
opendkim-testkey -d domain.name -s selectorname -vv -k keys/keyname.private
 
This will try to fetch the key published in DNS, so "record not found" means DNS record not found. No output is good output.
 
*[https://www.dmarcanalyzer.com/nl/dkim-record-validatie/ https://www.dmarcanalyzer.com/nl/dkim-record-validatie/]
 
==WARNING:Unsafe permissions==
make readable for user opendkim only
 
 
==keys do not match==
Try
opendkim-testkey -d domain.name -s selectorname -vv


= FAQ =
= FAQ =
== opendkim: no signing table match for ==
In opendkim.conf use:
refile:/etc/opendkim/SigningTable
==opendkim-testkey==
=== opendkim-testkey key not secure ===
Probably means you have no DNSSEC
===opendkim-testkey: keys do not match===
probably means double check Keytable
===opendkim-testkey: invalid data set type===
bad dns record?
===opendkim-testkey: multiple DNS replies ===
bad dns record?
== opendkim: /etc/opendkim.conf: /etc/opendkim/keys/default.private: open(): No such file or directory ==
Means it's defined in opendkim.conf, and you're not using KeyTable
 
== This doesn't seem to be a valid RSA public key: RSA.xs:178: OpenSSL error: bad base64 decode ==
??
== opendkim.service: Start request repeated too quickly. ==
Probably rights somewhere, try
opendkim -v
[[Category:Mail]]
[[Category:Mail]]

Latest revision as of 08:41, 27 August 2024

DomainKeys Identified Mail


Links

DKIMvalidator

HOWTO

Check if keys match

dig myselector._domainkey.example.com txt

and save the bit from "p=" to public.key.b64 

openssl enc -base64 -d -in public.key.b64 -out public.key
openssl rsa -pubin -inform DER -in public.key -noout -modulus

and compare the shown modulus with 

openssl rsa -in private.key -noout -modulus

They should be identical

FAQ

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