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242 lines
8.0 KiB
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OpenSSL For Apache and Dovecot: Part 2
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============================================================
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In this tutorial, Carla Schroder explains how to protect your Postfix/Dovecot mail server with OpenSSL.[Creative Commons Zero][1]Pixabay
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[Last week][11], as part of our meandering OpenSSL series, we learned how to configure Apache to use OpenSSL and to force all sessions to use HTTPS. Today, we'll protect our Postfix/Dovecot mail server with OpenSSL. The examples build on the previous tutorials; see the Resources section at the end for links to all previous tutorials in this series.
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You will have to configure both Postfix and Dovecot to use OpenSSL, and we'll use the key and certificate that we created in [OpenSSL For Apache and Dovecot ][12].
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### Postfix Configuration
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You must edit `/etc/postfix/main.cf` and `/etc/postfix/master.cf`. The `main.cf`example is the complete configuration, building on our previous tutorials. Substitute your own OpenSSL key and certificate names, and local network:
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```
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compatibility_level=2
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smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu/GNU)
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biff = no
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append_dot_mydomain = no
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myhostname = localhost
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alias_maps = hash:/etc/aliases
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alias_database = hash:/etc/aliases
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myorigin = $myhostname
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mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128 192.168.0.0/24
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mailbox_size_limit = 0
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recipient_delimiter = +
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inet_interfaces = all
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virtual_mailbox_domains = /etc/postfix/vhosts.txt
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virtual_mailbox_base = /home/vmail
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virtual_mailbox_maps = hash:/etc/postfix/vmaps.txt
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virtual_minimum_uid = 1000
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virtual_uid_maps = static:5000
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virtual_gid_maps = static:5000
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virtual_transport = lmtp:unix:private/dovecot-lmtp
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smtpd_tls_cert_file=/etc/ssl/certs/test-com.pem
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smtpd_tls_key_file=/etc/ssl/private/test-com.key
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smtpd_use_tls=yes
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smtpd_sasl_auth_enable = yes
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smtpd_sasl_type = dovecot
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smtpd_sasl_path = private/auth
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smtpd_sasl_authenticated_header = yes
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```
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In `master.cf` un-comment the following lines in the `submission inet` section, and edit `smtpd_recipient_restrictions` as shown:
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```
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#submission inet n - y - - smtpd
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-o syslog_name=postfix/submission
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-o smtpd_tls_security_level=encrypt
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-o smtpd_sasl_auth_enable=yes
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-o milter_macro_daemon_name=ORIGINATING
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-o smtpd_recipient_restrictions=permit_mynetworks,permit_sasl_authenticated,reject
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-o smtpd_tls_wrappermode=no
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```
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Reload Postfix and you're finished:
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```
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$ sudo service postfix reload
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```
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### Dovecot Configuration
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In our previous tutorials we made a single configuration file for Dovecot, `/etc/dovecot/dovecot.conf`, rather than using the default giant herd of multiple configuration files. This is a complete configuration that builds on our previous tutorials. Again, use your own OpenSSL key and certificate, and your own `userdb` home file:
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```
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protocols = imap pop3 lmtp
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log_path = /var/log/dovecot.log
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info_log_path = /var/log/dovecot-info.log
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disable_plaintext_auth = no
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mail_location = maildir:~/.Mail
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pop3_uidl_format = %g
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auth_mechanisms = plain
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passdb {
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driver = passwd-file
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args = /etc/dovecot/passwd
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}
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userdb {
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driver = static
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args = uid=vmail gid=vmail home=/home/vmail/studio/%u
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}
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service lmtp {
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unix_listener /var/spool/postfix/private/dovecot-lmtp {
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group = postfix
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mode = 0600
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user = postfix
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}
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}
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protocol lmtp {
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postmaster_address = postmaster@studio
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}
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service lmtp {
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user = vmail
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}
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service auth {
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unix_listener /var/spool/postfix/private/auth {
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mode = 0660
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user=postfix
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group=postfix
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}
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}
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ssl=required
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ssl_cert = </etc/ssl/certs/test-com.pem
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ssl_key = </etc/ssl/private/test-com.key
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```
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Restart Dovecot:
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```
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$ sudo service postfix reload
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```
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### Testing With Telnet
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Now we can test our setup by sending a message with telnet, just like we did before. But wait, you say, telnet does not support TLS/SSL, so how can this be so? By opening an encrypted session with `openssl s_client` first is how. The `openssl s_client` output will display your certificate, fingerprint, and a ton of other information so you'll know that your server is using the correct certificate. Commands that you type after the session is established are in bold:
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```
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$ openssl s_client -starttls smtp -connect studio:25
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CONNECTED(00000003)
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[masses of output snipped]
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Verify return code: 0 (ok)
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---
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250 SMTPUTF8
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EHLO studio
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250-localhost
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250-PIPELINING
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250-SIZE 10240000
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250-VRFY
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250-ETRN
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250-AUTH PLAIN
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250-ENHANCEDSTATUSCODES
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250-8BITMIME
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250-DSN
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250 SMTPUTF8
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mail from: <carla@domain.com>
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250 2.1.0 Ok
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rcpt to: <alrac@studio>
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250 2.1.5 Ok
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data
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354 End data with .subject: TLS/SSL test
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Hello, we are testing TLS/SSL. Looking good so far.
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.
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250 2.0.0 Ok: queued as B9B529FE59
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quit
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221 2.0.0 Bye
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```
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You should see a new message in your mail client, and it will ask you to verify your SSL certificate when you open it. You may also use `openssl s_client`to test your Dovecot POP3 and IMAP services. This example tests encrypted POP3, and message #5 is the one we created in telnet (above):
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```
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$ openssl s_client -connect studio:995
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CONNECTED(00000003)
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[masses of output snipped]
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Verify return code: 0 (ok)
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---
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+OK Dovecot ready
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user alrac@studio
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+OK
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pass password
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+OK Logged in.
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list
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+OK 5 messages:
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1 499
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2 504
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3 514
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4 513
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5 565
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.
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retr 5
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+OK 565 octets
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Return-Path: <carla@domain.com>
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Delivered-To: alrac@studio
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Received: from localhost
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by studio.alrac.net (Dovecot) with LMTP id y8G5C8aablgKIQAAYelYQA
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for <alrac@studio>; Thu, 05 Jan 2017 11:13:10 -0800
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Received: from studio (localhost [127.0.0.1])
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by localhost (Postfix) with ESMTPS id B9B529FE59
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for <alrac@studio>; Thu, 5 Jan 2017 11:12:13 -0800 (PST)
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subject: TLS/SSL test
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Message-Id: <20170105191240.B9B529FE59@localhost>
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Date: Thu, 5 Jan 2017 11:12:13 -0800 (PST)
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From: carla@domain.com
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Hello, we are testing TLS/SSL. Looking good so far.
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.
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quit
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+OK Logging out.
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closed
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```
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### Now What?
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Now you have a nice functioning mail server with proper TLS/SSL protection. I encourage you to study Postfix and Dovecot in-depth; the examples in these tutorials are as simple as I could make them, and don't include fine-tuning for security, anti-virus scanners, spam filters, or any other advanced functionality. I think it's easier to learn the advanced features when you have a basic working system to use.
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Come back next week for an openSUSE package management cheat sheet.
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### Resources
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* [OpenSSL For Apache and Dovecot][3]
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* [How to Build an Email Server on Ubuntu Linux][4]
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* [Building an Email Server on Ubuntu Linux, Part 2][5]
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* [Building an Email Server on Ubuntu Linux, Part 3][6]
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* [Apache on Ubuntu Linux For Beginners][7]
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* [Apache on Ubuntu Linux For Beginners: Part 2][8]
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* [Apache on CentOS Linux For Beginners][9]
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* [Quieting Scary Web Browser SSL Alerts][10]
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--------------------------------------------------------------------------------
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via: https://www.linux.com/learn/intro-to-linux/openssl-apache-and-dovecot-part-2
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作者：[CARLA SCHRODER][a]
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译者：[译者ID](https://github.com/译者ID)
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校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]:https://www.linux.com/users/cschroder
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[1]:https://www.linux.com/licenses/category/creative-commons-zero
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[2]:https://www.linux.com/files/images/key-openssljpg-0
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[3]:https://www.linux.com/learn/sysadmin/openssl-apache-and-dovecot
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[4]:https://www.linux.com/learn/how-build-email-server-ubuntu-linux
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[5]:https://www.linux.com/learn/sysadmin/building-email-server-ubuntu-linux-part-2
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[6]:https://www.linux.com/learn/sysadmin/building-email-server-ubuntu-linux-part-3
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[7]:https://www.linux.com/learn/apache-ubuntu-linux-beginners
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[8]:https://www.linux.com/learn/apache-ubuntu-linux-beginners-part-2
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[9]:https://www.linux.com/learn/apache-centos-linux-beginners
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[10]:https://www.linux.com/learn/quieting-scary-web-browser-ssl-alerts
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[11]:https://www.linux.com/learn/sysadmin/openssl-apache-and-dovecot
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[12]:https://www.linux.com/learn/sysadmin/openssl-apache-and-dovecot
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