SSL Setting
2017/12/23 |
Configure SSL to encrypt connections.
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[1] | |
[2] | Configure Postfix and Dovecot for SSL. |
[root@mail ~]#
vi /etc/postfix/main.cf # add to the end smtpd_use_tls = yes
smtp_tls_mandatory_protocols = !SSLv2, !SSLv3 smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3 smtpd_tls_CAfile = /etc/pki/tls/certs/ca-bundle.crt smtpd_tls_cert_file = /etc/pki/tls/certs/server.crt smtpd_tls_key_file = /etc/pki/tls/certs/server.key smtpd_tls_session_cache_database = btree:/etc/postfix/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 29-31: uncomment smtps inet n - n - - smtpd -o syslog_name=postfix/smtps -o smtpd_tls_wrappermode=yes
[root@mail ~]#
vi /etc/dovecot/conf.d/10-ssl.conf # line 8: change ssl = yes
# line 14,15: specify certificates ssl_cert = < /etc/pki/tls/certs/server.crt ssl_key = < /etc/pki/tls/certs/server.key
# line 26: specify CA file ssl_ca = < /etc/pki/tls/certs/ca-bundle.crt
# line 51: uncomment ssl_protocols = !SSLv3 systemctl restart postfix dovecot
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[3] | 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 |
[4] | 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]) |
[5] | 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]) |
[6] | If your own self-signed certificates, the warning like follows are displayed, but it's no ploblem to proceed. Then it's possible to send or receive emails through STARTTLS or SSL/TLS connection. |