Difference between revisions of "OpenDKIM"
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== Basic configuration == | == Basic configuration == | ||
− | * Generate key: | + | * Generate key (server1 is the selector that is specified in the conf file below): |
opendkim-genkey -r -s server1 -d example.com | opendkim-genkey -r -s server1 -d example.com | ||
* Create {{ic|/etc/opendkim/opendkim.conf}} (see example in the same directory) | * Create {{ic|/etc/opendkim/opendkim.conf}} (see example in the same directory) |
Revision as of 02:52, 21 April 2013
DomainKeys Identified Mail is a digital email signing/verification technology, which is already supported by some common mail providers. (For example yahoo, google, etc).
The idea
Basically DKIM means digitally signing all messages on the server to verify the message actually was sent from the domain in question and is not spam or pishing (and has not been modified).
- The sender's mail server signs outgoing email with the private key.
- When the message arrives, the receiver (or his server) requests the public key from the domain's DNS and verifies the signature.
This ensures the message was sent from a server who's private key matches the domain's public key.
For more info see RFC 6376
Installation
Install the package opendkim from the Official repositories.
You may add an user for opendkim or use existing one (for example: postfix)
Basic configuration
- Generate key (server1 is the selector that is specified in the conf file below):
opendkim-genkey -r -s server1 -d example.com
- Create
/etc/opendkim/opendkim.conf
(see example in the same directory)
Minimal config:
/etc/opendkim/opendkim.conf
Domain example.com KeyFile /path/to/keys/server1.private Selector server1 Socket inet:8891@localhost UserID opendkim
- Add a DNS TXT record with your selector and public key. The correct record is generated with the private key and can be found in
server1.txt
in the same location as the private key.
- Enable and start the
opendkim.service
. Read Daemons for more information.
Postfix integration
Just add
non_smtpd_milters=inet:127.0.0.1:8891
and/or
smtpd_milters=inet:127.0.0.1:8891
into main.cf or smtpd options in master.cf
master.cf example:
smtp inet n - n - - smtpd -o smtpd_client_connection_count_limit=10 -o smtpd_milters=inet:127.0.0.1:8891 submission inet n - n - - smtpd -o smtpd_enforce_tls=no -o smtpd_sasl_auth_enable=yes -o smtpd_client_restrictions=permit_sasl_authenticated,reject -o smtpd_sasl_path=smtpd -o cyrus_sasl_config_path=/etc/sasl2 -o smtpd_milters=inet:127.0.0.1:8891
Notes
While you're about to fight spam and increase people's trust in your server, you might want to take a look at Sender Policy Framework, which basically means adding a DNS Record stating which servers are authorized to send email for your domain.