15.11.2016 lomix

DKIM + Postfix + CentOS 7 (digitalni potpis za e-poštu)

server:/ # apt-get install opendkim opendkim-tools Kreiramo posebnu fasciklu za OpenDKIM i premestamo konfiguracioni fajl u tu fasciklu. Zbog kompatibilnosti, ostavljamo link na starom mestu. 1 2 3 4 server:/ # mkdir /etc/opendkim server:/ # chown opendkim:opendkim /etc/opendkim server:/ #…

server:/# apt-get install opendkim opendkim-tools

Kreirajmo posebnu fasciklu za OpenDKIM i premestimo konfiguracioni fajl u tu fasciklu. Zbog kompatibilnosti, ostavićemo link na starom mestu.

server:/# mkdir /etc/opendkim 
server:/# chown opendkim:opendkim /etc/opendkim
server:/# mv /etc/opendkim.conf /etc/opendkim/opendkim.conf
server:/# ln -s /etc/opendkim/opendkim.conf /etc/opendkim.conf

Izmenićemo konfiguraciju i dodati potrebne parametre:

PidFile /var/run/opendkim/opendkim.pid
Syslog yes
UserID opendkim:opendkim
Socket inet:8891@localhost
Umask 002
SendReports yes
SoftwareHeader yes
MinimumKeyBits 1024
SyslogSuccess yes
LogWhy yes
X-Header yes
OversignHeaders From
Selector mail
Canonicalization relaxed/relaxed
Mode sv
SubDomains no
KeyTable file:/etc/opendkim/KeyTable
SigningTable file:/etc/opendkim/SigningTable
AutoRestart yes
DNSTimeout 5

ExternalIgnoreList file:/etc/opendkim/TrustedHosts
InternalHosts file:/etc/opendkim/TrustedHosts
#Statistics /var/log/dkim-stats

Kreirajmo potrebne fajlove i fascikle (inventar) za naš poštanski server, posebno... U budućnosti, svakog novog klijenta ćemo dodavati na sličan način.

server:/# mkdir /etc/opendkim/demon.of.by
server:/# chown opendkim:opendkim /etc/opendkim/demon.of.by

Kreirajmo direktno ključeve za domen demon.of.by, a zatim promenimo vlasnika ključeva na korisnika opendkim:

server:/# cd /etc/opendkim/demon.of.by
server:/# opendkim-genkey -s mail -d demon.of.by
server:/# chown opendkim:opendkim *

server:/# cat /etc/opendkim/demon.of.by/mail.txt
mail._domainkey IN TXT "v=DKIM1; k=rsa; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDH5t3M0b3DQEBAQUAA4EWRL+S4/yWauDq6C2srD9UptvXdI40YS0aUywyj2XT1TbeNdrLjGZ764kTUwshuqKToa9pUjwT/TPOx939VA8FWV32bC1hE97dgK3mhFpNurp7K3ZH4sDPTz4Qnlpa8kWZ/iThkTPpNYf5LTwIDAQAB" ; ----- DKIM key mail for demon.of.by

Ovde uzimamo sadržaj u navodnicima i postavljamo ga u DNS TXT zapis našeg domena:

mail._domainkey.demon.of.by. IN TXT "v=DKIM1; k=rsa; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDH5t3M0b3DQEBAQUAA4EWRL+S4/yWauDq6C2srD9UptvXdI40YS0aUywyj2XT1TbeNdrLjGZ764kTUwshuqKToa9pUjwT/TPOx939VA8FWV32bC1hE97dgK3mhFpNurp7K3ZH4sDPTz4Qnlpa8kWZ/iThkTPpNYf5LTwIDAQAB"

Dodatno definišemo zapis za servere na kojima nije podešen DKIM (za sve klijente ova direktiva je ista)

_adsp._domainkey.demon.of.by. IN TXT "dkim=unknown"

Napomena: U ovom primeru treba da zamenite domen demon.of.by svojim sopstvenim, na primer example.com

Konfigurišemo OpenDKIM servis da služi domen demon.of.by. Dodajemo novi ključ u fajl sa ključevima:

server:/# vim /etc/opendkim/KeyTable
# To use this file, uncomment the #KeyTable option in /etc/opendkim.conf,
# then uncomment the following line and replace example.com with your domain
# name, then restart OpenDKIM. Additional keys may be added on separate lines.
mail._domainkey.demon.of.by demon.of.by:mail:/etc/opendkim/demon.of.by/mail.private

Odredjujemo servisu kojim ključem da potpisuje poštu za koji domen

server:/# vim /etc/opendkim/SigningTable
demon.of.by mail._domainkey.demon.of.by

Odredjujemo servisu naše poverljive hostove

server:/# vim /etc/opendkim/TrustedHosts
# To use this file, uncomment the #ExternalIgnoreList and/or the #InternalHosts
# option in /etc/opendkim.conf then restart OpenDKIM. Additional hosts
# may be added on separate lines (IP addresses, hostnames, or CIDR ranges).
# The localhost IP (127.0.0.1) should be the first entry in this file.
127.0.0.1
demon.of.by

Ne zaboravimo da navedemo na kom portu naš OpenDKIM treba da sluša. Uredićemo /etc/default/opendkim:

server:/# vim /etc/default/opendkim
# Command-line options specified here will override the contents of
# /etc/dkim-filter.conf. See dkim-filter(8) for a complete list of options.
#DAEMON_OPTS=""
#
# Uncomment to specify an alternate socket
# Note that setting this will override any Socket value in dkim-filter.conf
#SOCKET="local:/var/run/dkim-filter/dkim-filter.sock" # Debian default
#SOCKET="inet:54321" # listen on all interfaces on port 54321
#SOCKET="inet:12345@192.0.2.1" # listen on 192.0.2.1 on port 12345
SOCKET="inet:8891@localhost" # By default - listen on loopback on port 8891

U našem slučaju to je port 8891.

Restartujemo OpenDKIM

server:/# /etc/init.d/opendkim restart
Mar  3 15:01:26 ip-10-71-153-106 opendkim[8303]: OpenDKIM Filter v2.6.8 starting (args: -x /etc/opendkim.conf -u opendkim -P /var/run/opendkim/opendkim.pid -p inet:8891@localhost)

Završni akord, dodajemo OpenDKIM u Postfix. Da bismo to uradili, uredićemo /etc/postfix/main.cf i dodati sledeće redove:

server:/# vim /etc/postfix/main.cf
# DKIM
milter_default_action = accept
milter_protocol = 2
smtpd_milters = inet:localhost:8891
non_smtpd_milters = inet:localhost:8891

Napomena: Ako koristite više obradača (na primer Postfix/DomainKeys), možete dodati više njih istovremeno, kao što je prikazano u nastavku:

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milter_default_action = accept

milter_protocol = 2

smtpd_milters = inet:localhost:8891,inet:localhost:8892

non_smtpd_milters = inet:localhost:8891,inet:localhost:8892

Restartujemo Postfix

server:/# /etc/init.d/postfix restart

Šaljemo testne poruke na sledeće adrese:

check-auth@verifier.port25.com
sa-test@sendmail.net
autorespond+dkim@dk.elandsys.com

Pažljivo analizirajte odgovore.

Napomena: tekst može biti uz pomoć AI uz ljudsku proveru. Odgovoran: Dmytro Lomaka, Kaltenkirchen.

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