UPDATE THE SYSTEM
Before going any further, make sure you’re in a screen session and your system is fully up-to-date by running:
## screen -U -S opendkim-screen ## yum update
ENABLE EPEL REPOSITORY
OpenDKIM is available in the EPEL repository, so we need to enable it on the system before we can install OpenDKIM
## wget -P /tmp http://mirror.pnl.gov/epel/6/i386/epel-release-6-8.noarch.rpm ## rpm -Uvh /tmp/epel-release-6-8.noarch.rpm ## rm -f /tmp/epel-release-6-8.noarch.rpm
INSTALL OPENDKIM
Install the package using yum:
## yum install opendkim
CONFIGURE OPENDKIM
Next thing to do is to configure OpenDKIM. Its main configuration file is located in /etc/opendkim.conf, so before making any changes create a backup and add/edit the following:
## cp /etc/opendkim.conf /etc/opendkim.conf.bal ## vim /etc/opendkim.conf
Paste the below configuration parameters:
AutoRestart Yes AutoRestartRate 10/1h LogWhy Yes Syslog Yes SyslogSuccess Yes Mode sv Canonicalization relaxed/simple ExternalIgnoreList refile:/etc/opendkim/TrustedHosts InternalHosts refile:/etc/opendkim/TrustedHosts KeyTable refile:/etc/opendkim/KeyTable SigningTable refile:/etc/opendkim/SigningTable SignatureAlgorithm rsa-sha256 Socket inet:8891@localhost PidFile /var/run/opendkim/opendkim.pid UMask 022 UserID opendkim:opendkim TemporaryDirectory /var/tmp
SET-UP PUBLIC/PRIVATE KEYS
Generate set of keys for your mydomain.com domain name:
## mkdir /etc/opendkim/keys/mydomain.com ## opendkim-genkey -D /etc/opendkim/keys/mydomain.com/ -d mydomain.com -s default ## chown -R opendkim: /etc/opendkim/keys/mydomain.com ## mv /etc/opendkim/keys/mydomain.com/default.private /etc/opendkim/keys/mydomain.com/default
add mydomain.com to OpenDKIM’s key table by adding the following record in /etc/opendkim/KeyTable
default._domainkey.mydomain.com mydomain.com:default:/etc/opendkim/keys/mydomain.com/default
next, edit /etc/opendkim/SigningTable and add the following record to OpenDKIM’s signing table:
*@mydomain.com default._domainkey.mydomain.com
and add your domain and your hostname as trusted hosts in /etc/opendkim/TrustedHosts:
127.0.0.1 mydomain.com host.mydomain.com
assuming the domain in question is ‘mydomain.com’ and server’s hostname is set to ‘host.mydomain.com’
finally, edit your mydomain.com DNS zone and add the TXT record from /etc/opendkim/keys/mydomain.com/default.txt
default._domainkey IN TXT ( "v=DKIM1; k=rsa; " "p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDApHRr7ZmXRaAB+RQRbP4VdMwIrIHIP18KFtXRsv/xpWc0Gix6ZXN13fcG03KNGKZo2PY+csPkGC5quDnH5V0JEhDZ78KcDWFsU6u4fr9ktVAdt6P7jWXjcyqdHOZ8+YN4cAeU4lRFNgQvdupIcByYwzPYMgBFHfJm9014HvRqhwIDAQAB" ) ; ----- DKIM key default for mydomain.com
You can verify your dkim TXT record is valid using dig for example:
## dig +short default._domainkey.mydomain.com TXT
"v=DKIM1\; k=rsa\; " "p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDApHRr7ZmXRaAB+RQRbP4VdMwIrIHIP18KFtXRsv/xpWc0Gix6ZXN13fcG03KNGKZo2PY+csPkGC5quDnH5V0JEhDZ78KcDWFsU6u4fr9ktVAdt6P7jWXjcyqdHOZ8+YN4cAeU4lRFNgQvdupIcByYwzPYMgBFHfJm9014HvRqhwIDAQAB"
CONFIGURE POSTFIX
In order to integrate OpenDKIM with Postfix we need to add the following few lines in /etc/postfix/main.cf:
smtpd_milters = inet:127.0.0.1:8891 non_smtpd_milters = $smtpd_milters milter_default_action = accept milter_protocol = 2
(RE)START SERVICES
Add OpenDKIM to your system’s start-up and start opendkim and restart postfix using the following commands:
## service opendkim start ## chkconfig opendkim on ## service postfix restart
TEST THE SET-UP
To test the set-up simply send an email to check-auth@verifier.port25.com and you should receive back an email containing something like this:
========================================================== Summary of Results ========================================================== SPF check: pass DomainKeys check: neutral DKIM check: pass DKIM check: pass
Src: https://www.rosehosting.com/blog/how-to-install-and-integrate-opendkim-with-postfix-on-a-centos-6-vps/
