Contents
1.Obtain an SSL certificate ( Let's Encrypt )
Install the latest open ssl
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# dnf install openssl-devel |
1.1 advance preparation
1.Package management system Snappy installed
Since the SSL certificate issuing tool "certbot" of Let's Encrypt is recommended to be installed using "snap" after 2021, install Snapd first.(Can also be installed the traditional way with dnf or yum)
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# dnf upgrade # dnf install snapd |
Enable systemd unit to manage the main snap communication socket
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# systemctl enable --now snapd.socket Created symlink /etc/systemd/system/sockets.target.wants/snapd.socket → /usr/lib/systemd/system/snapd.socket. |
Enable Classics Snap support
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# ln -s /var/lib/snapd/snap /snap |
Version Check
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# snap --version snap 2.65.1-0.fc41 snapd 2.65.1-0.fc41 series 16 fedora 41 kernel 6.11.4-301.fc41.x86_64 |
Log out and log in again or reboot the system to ensure that the snap path is updated correctly
2.certbot package install
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# snap install --classic certbot certbot 2.11.0 from Certbot Project (certbot-eff✓) installed |
Create symbolic link to /snap/bin/certbot
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# ln -s /snap/bin/certbot /usr/bin/certbot |
Confirmation
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# ls -la /usr/bin/certbot lrwxrwxrwx 1 root root 17 Nov 11 13:30 /usr/bin/certbot -> /snap/bin/certbot # ls -la /snap/bin/certbot lrwxrwxrwx 1 root root 13 Nov 11 13:29 /snap/bin/certbot -> /usr/bin/snap |
1.2 Obtaining Certificates
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# certbot certonly --webroot -w /var/www/html/[FQDN] -d [FQDN] |
Registration of e-mail address and agreement to terms of use are required for the first time only.
Specify an email address to receive
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Saving debug log to /var/log/letsencrypt/letsencrypt.log Enter email address (used for urgent renewal and security notices) (Enter 'c' to cancel): [mail address] - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - https://letsencrypt.org/documents/LE-SA-v1.4-April-3-2024.pdf. You must agree in order to register with the ACME server. Do you agree? - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - (Y)es/(N)o: y - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Would you be willing, once your first certificate is successfully issued, to share your email address with the Electronic Frontier Foundation, a founding partner of the Let's Encrypt project and the non-profit organization that develops Certbot? We'd like to send you email about our work encrypting the web, EFF news, campaigns, and ways to support digital freedom. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - (Y)es/(N)o: y Account registered. Requesting a certificate for [FQDN] Successfully received certificate. Certificate is saved at: /etc/letsencrypt/live/[FQDN]/fullchain.pem Key is saved at: /etc/letsencrypt/live/[FQDN]/privkey.pem This certificate expires on 2025-02-02. These files will be updated when the certificate renews. Certbot has set up a scheduled task to automatically renew this certificate in the background. We were unable to subscribe you the EFF mailing list because your e-mail address appears to be invalid. You can try again later by visiting https://act.eff.org. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - If you like Certbot, please consider supporting our work by: * Donating to ISRG / Let's Encrypt: https://letsencrypt.org/donate * Donating to EFF: https://eff.org/donate-le - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - |
Success if displayed"Successfully received certificate".
# The following certificate is obtained under [/etc/letsencrypt/live/[FQDN]/] as described in the message
# cert.pem ⇒ SSL server certificate (including public key)
# chain.pem ⇒ intermediate certificate
# fullchain.pem ⇒ File containing cert.pem and chain.pem combined
# privkey.pem ⇒ private key
It is a prerequisite that the server on which the work is to be performed is accessible from the Internet at port 80.
FQDN (Fully Qualified Domain Name) :Hostname. Domain name without abbreviation
If there are multiple FQDNs for which you want to obtain certificates, specify multiple -d [FQDNs] for which you want to obtain certificates
Renewing certificates already obtained
# Renew all certificates with an expiration date of less than 30 days
# If you want to renew regardless of the number of days remaining on the expiration date, specify [--force-renewal] as well.
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# certbot [--force-renewal] renew Saving debug log to /var/log/letsencrypt/letsencrypt.log - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Processing /etc/letsencrypt/renewal/[FQDN].conf - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Renewing an existing certificate for [FQDN] - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Congratulations, all renewals succeeded: /etc/letsencrypt/live/[FQDN]/fullchain.pem (success) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - |
1.2 Automatic renewal of certificates(Let's Encrypt)
①Pre-registration testing
First, test the automatic update using the following --dry-run option.
With this option, certificates are not renewed, only checked, so there is no need to worry about getting stuck with a limit on the number of times a certificate can be obtained.
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# certbot renew --dry-run |
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Saving debug log to /var/log/letsencrypt/letsencrypt.log - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Processing /etc/letsencrypt/renewal/[FQDN].conf - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Account registered. Simulating renewal of an existing certificate for [FQDN] - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Congratulations, all simulated renewals succeeded: /etc/letsencrypt/live/[FQDN]/fullchain.pem (success) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - |
②When you install the snap version of certbot, the automatic certificate renewal function is also installed.
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# systemctl list-timers | less NEXT LEFT LAST PASSED UNIT ACTIVATES Tue 2024-11-05 10:34:29 JST 33min Tue 2024-11-05 09:31:22 JST 29min ago fwupd-refresh.timer fwupd-refresh.service Tue 2024-11-05 18:52:00 JST 8h Tue 2024-11-05 09:54:02 JST 6min ago snap.certbot.renew.timer snap.certbot.renew.service Wed 2024-11-06 00:00:00 JST 13h - - sa-update.timer sa-update.service Wed 2024-11-06 00:01:44 JST 14h Tue 2024-11-05 09:32:32 JST 28min ago logrotate.timer logrotate.service Wed 2024-11-06 00:36:22 JST 14h Tue 2024-11-05 09:35:52 JST 24min ago plocate-updatedb.timer plocate-updatedb.service Wed 2024-11-06 09:40:12 JST 23h Tue 2024-11-05 09:40:12 JST 20min ago systemd-tmpfiles-clean.timer systemd-tmpfiles-clean.service Sun 2024-11-10 01:00:00 JST 4 days Sun 2024-11-03 10:49:23 JST - raid-check.timer raid-check.service Mon 2024-11-11 00:12:43 JST 5 days Mon 2024-11-04 09:05:31 JST - fstrim.timer fstrim.service 8 timers listed. Pass --all to see loaded but inactive timers, too. |
snap.certbot.renew.timer is registered
Check the unit file snap.certbot.renew.timer
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# vi /etc/systemd/system/snap.certbot.renew.timer [Unit] # Auto-generated, DO NOT EDIT Description=Timer renew for snap application certbot.renew Requires=var-lib-snapd-snap-certbot-3700.mount After=var-lib-snapd-snap-certbot-3700.mount X-Snappy=yes [Timer] Unit=snap.certbot.renew.service OnCalendar=*-*-* 09:21 OnCalendar=*-*-* 22:46 [Install] WantedBy=timers.target |
According to the above configuration, it will attempt to update at 09:21 and 22:46 every day as specified in the OnCalender parameter(However, the set time changes randomly with each update)
Check the unit file snap.certbot.renew.service
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# vi /etc/systemd/system/snap.certbot.renew.service [Unit] # Auto-generated, DO NOT EDIT Description=Service for snap application certbot.renew Requires=var-lib-snapd-snap-certbot-3700.mount Wants=network.target After=var-lib-snapd-snap-certbot-3700.mount network.target snapd.apparmor.service X-Snappy=yes [Service] EnvironmentFile=-/etc/environment ExecStart=/usr/bin/snap run --timer="00:00~24:00/2" certbot.renew SyslogIdentifier=certbot.renew Restart=no WorkingDirectory=/var/snap/certbot/3700 TimeoutStopSec=30 Type=oneshot |
However, the web server using the certificate will not be restarted, so set up a script to run automatically after the update
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# vi /etc/letsencrypt/renewal-hooks/post/web_restart.sh Describe the following #!/bin/bash systemctl reload httpd |
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# chmod 755 /etc/letsencrypt/renewal-hooks/post/web_restart.sh |
2. Converting Apache to https
Install the following just in case
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# dnf -y install mod_ssl |
2.1 Edit ssl.conf file
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# vi /etc/httpd/conf.d/ssl.conf Line 59 : Uncomment and change DocumentRoot "/var/www/html/[FQDN]" Line 60 : Uncomment and change ServerName [FQDN]:443 Line 101 : Make it a comment and add it below # SSLCertificateFile /etc/pki/tls/certs/localhost.crt SSLCertificateFile /etc/letsencrypt/live/[FQDN]/cert.pem Line 109 : Make it a comment and add it below # SSLCertificateKeyFile /etc/pki/tls/private/localhost.key SSLCertificateKeyFile /etc/letsencrypt/live/[FQDN]/privkey.pem Line 119 : Add SSLCertificateChainFile /etc/letsencrypt/live/[FQDN]/chain.pem |
Restart Apache.
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# systemctl restart httpd |
Allow https in Firewall
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# firewall-cmd --add-service=https --permanent success # firewall-cmd --reload success |
2.2 Redirect HTTP communications to HTTPS
Create .htaccess under /var/www/html/[FQDN]/.
Contents of .htaccess
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RewriteEngine On RewriteCond %{HTTPS} off RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [R=301,L] |
3. SSL/TLS (Let's Encrypt) settings on the mail server
3.1 Obtaining a certificate for the mail server
Obtain a certificate for the mail server, but it cannot be obtained in the same way as above, so the following with the "--standalone" option fails.
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# certbot certonly --standalone -d mail.[domain name] |
If I stop the web server once and then do it, it succeeds as follows
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# systemctl stop httpd.service # certbot certonly --standalone -d mail.[domain name] |
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Saving debug log to /var/log/letsencrypt/letsencrypt.log Requesting a certificate for mail.[domain name] Successfully received certificate. Certificate is saved at: /etc/letsencrypt/live/mail.[domain name]/fullchain.pem Key is saved at: /etc/letsencrypt/live/mail.[domain name]/privkey.pem This certificate expires on 2025-02-03. These files will be updated when the certificate renews. Certbot has set up a scheduled task to automatically renew this certificate in the background. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - If you like Certbot, please consider supporting our work by: * Donating to ISRG / Let's Encrypt: https://letsencrypt.org/donate * Donating to EFF: https://eff.org/donate-le - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - |
3.2 Postfix Configuration
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# vi /etc/postfix/main.cf Per Line 719, 725 : comment #smtpd_tls_cert_file = /etc/pki/tls/certs/postfix.pem #smtpd_tls_key_file = /etc/pki/tls/private/postfix.key Add to the last line smtpd_use_tls = yes smtp_tls_mandatory_protocols = !SSLv2, !SSLv3 smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3 smtpd_tls_cert_file = /etc/letsencrypt/live/mail.[domain name]/fullchain.pem smtpd_tls_key_file = /etc/letsencrypt/live/mail.[domain name]/privkey.pem smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache |
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# vi /etc/postfix/master.cf Line 19-22 : Uncomment submission inet n - n - - smtpd -o syslog_name=postfix/submission -o smtpd_tls_security_level=encrypt -o smtpd_sasl_auth_enable=yes Line 38-41 : Uncomment submissions inet n - n - - smtpd -o syslog_name=postfix/smtps -o smtpd_tls_wrappermode=yes -o smtpd_sasl_auth_enable=yes |
3.3 Dovecot Settings
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# vi /etc/dovecot/conf.d/10-ssl.conf Line 9：confirmation ssl = yes Line 14,15：Make it a comment and add certificate/key file designation under it #ssl_cert = </etc/pki/dovecot/certs/dovecot.pem #ssl_key = </etc/pki/dovecot/private/dovecot.pem ssl_cert = </etc/letsencrypt/live/mail.[domain name]/fullchain.pem ssl_key = </etc/letsencrypt/live/mail.[domain name]/privkey.pem |
Allow Port 587 in firewall
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# firewall-cmd --add-port=587/tcp --permanent # firewall-cmd --reload |
Restart
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# systemctl restart postfix dovecot |
3.4 Thunderbird Settings
Receiving servers
Port : 143
Connection security : STARTTLS
Authentication method : Normal password
Sending server
Port : 587
Connection security : STARTTLS
Authentication method : Normal password
