Mail Server : SSL/TLS Setting2019/11/07 |
Configure SSL/TLS to encrypt connections.
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[1] | |
[2] | Configure Postfix and Dovecot. |
[root@mail ~]#
vi /etc/postfix/main.cf # line 709, 715: comment out # smtpd_tls_cert_file = /etc/pki/tls/certs/postfix.pem# smtpd_tls_key_file = /etc/pki/tls/private/postfix.key
# add to the end (replace certificate to your own one) smtpd_use_tls = yes
smtp_tls_mandatory_protocols = !SSLv2, !SSLv3 smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3 smtpd_tls_cert_file = /etc/letsencrypt/live/mail.srv.world/fullchain.pem smtpd_tls_key_file = /etc/letsencrypt/live/mail.srv.world/privkey.pem smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
[root@mail ~]#
vi /etc/postfix/master.cf # line 17,18,20: uncomment submission inet n - n - - smtpd -o syslog_name=postfix/submission # -o smtpd_tls_security_level=encrypt -o smtpd_sasl_auth_enable=yes # line 29-32: uncomment smtps inet n - n - - smtpd -o syslog_name=postfix/smtps -o smtpd_tls_wrappermode=yes -o smtpd_sasl_auth_enable=yes
[root@mail ~]#
vi /etc/dovecot/conf.d/10-ssl.conf # line 8: change (if set SSL required, specify [required]) ssl = yes
# line 14,15: specify certificates ssl_cert = < /etc/letsencrypt/live/mail.srv.world/fullchain.pem ssl_key = < /etc/letsencrypt/live/mail.srv.world/privkey.pem
systemctl restart postfix dovecot
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[3] | If SELinux is enabled, restote context for certificates. |
[root@mail ~]# restorecon -v /etc/letsencrypt/live/mail.srv.world/fullchain.pem [root@mail ~]# restorecon -v /etc/letsencrypt/live/mail.srv.world/privkey.pem |
[4] | If Firewalld is running, allow SMTP-Submission/SMTPS/POP3S/IMAPS services. SMTP-Submission uses [587/TCP] (used STARTTLS), SMTPS uses [465/TCP], POP3S uses [995/TCP], IMAPS uses [993/TCP]. |
[root@mail ~]# firewall-cmd --add-service={smtp-submission,smtps,pop3s,imaps} --permanent success [root@mail ~]# firewall-cmd --reload success |
[5] | For Client's settings, ( Mozilla Thunderbird ) Open account's property and move to [Server Settings] on the left pane, then Select [STARTTLS] or [SSL/TLS] on [Connection security] field on the right pane. (this example shows to select [STARTTLS]) |
[6] | Move to [Outgoing Server] on the left pane, then Select [STARTTLS] or [SSL/TLS] on [Connection security] field. Furthermore, change port to the used port. ([STARTTLS] uses [587], [SSL/TLS] uses 465, this example shows to select [STARTTLS]) |
[7] | Make sure possible to send or receive Emails normally. |
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