Fedora 37
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Get SSL Certificate (Let's Encrypt)
2022/11/16
 
Get SSL Certificates from Let's Encrypt who provides Free SSL Certificates.
Refer to the details for Let's Encrypt official site below.
⇒ https://letsencrypt.org/
The expiration date of a cert is 90 days.
However, Systemd Timer which checks and updates certificates is included in Certbot pckage and you don't need to update manually.
[1] Install Certbot Client which is the tool to get certificates from Let's Encrypt.
[root@dlp ~]#
dnf -y install certbot
[2] Get certificates.
It needs Web server like Apache httpd or Nginx must be runing on the server you work.
If no Web server is running, skip this section and Refer to [3] section.
Furthermore, it needs that it's possible to access from the Internet to your working server on port 80 because of verification from Let's Encrypt.
# for the option [--webroot], use a directory under the webroot on your server as a working temp
# -w [document root] -d [FQDN you'd like to get certs]
# FQDN (Fully Qualified Domain Name) : Hostname.Domainname

# if you'd like to get certs for more than 2 FQDNs, specify all like below
# ex : if get [srv.world] and [www.srv.world]
# ⇒ [-d srv.world -d www.srv.world]

[root@dlp ~]# certbot certonly --webroot -w /var/www/html -d dns.srv.world 
Saving debug log to /var/log/letsencrypt/letsencrypt.log
Enter email address (used for urgent renewal and security notices)
# for only initial using, register your email address and agree to terms of use
# specify valid email address
 (Enter 'c' to cancel): root@mail.srv.world

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Please read the Terms of Service at
https://letsencrypt.org/documents/LE-SA-v1.2-November-15-2017.pdf. You must
agree in order to register with the ACME server. Do you agree?
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# agree to the terms of use
(Y)es/(N)o: A

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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.
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(Y)es/(N)o: A
Account registered.
Requesting a certificate for dns.srv.world

Successfully received certificate.
Certificate is saved at: /etc/letsencrypt/live/dns.srv.world/fullchain.pem
Key is saved at:         /etc/letsencrypt/live/dns.srv.world/privkey.pem
This certificate expires on 2022-07-25.
These files will be updated when the certificate renews.
Certbot has set up a scheduled task to automatically renew this certificate in the background.

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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
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# success if [Successfully received certificate] is shown
# certs are created under the [/etc/letsencrypt/live/(FQDN)/] directory

# cert.pem       ⇒  SSL Server cert(includes public-key)
# chain.pem      ⇒  intermediate certificate
# fullchain.pem  ⇒  combined file cert.pem and chain.pem
# privkey.pem    ⇒  private-key file
[3] If no Web Server is running on your working server, it's possbile to get certs with using Certbot's Web Server feature. Anyway, it needs that it's possible to access from the Internet to your working server on port 80 because of verification from Let's Encrypt.
# for the option [--standalone], use Certbot's Web Server feature
# -d [FQDN you'd like to get certs]
# FQDN (Fully Qualified Domain Name) : Hostname.Domainname

# if you'd like to get certs for more than 2 FQDNs, specify all like below
# ex : if get [srv.world] and [www.srv.world] ⇒ specify [-d srv.world -d www.srv.world]

[root@dlp ~]# certbot certonly --standalone -d rx-9.srv.world 
Saving debug log to /var/log/letsencrypt/letsencrypt.log
Requesting a certificate for rx-9.srv.world

Successfully received certificate.
Certificate is saved at: /etc/letsencrypt/live/rx-9.srv.world/fullchain.pem
Key is saved at:         /etc/letsencrypt/live/rx-9.srv.world/privkey.pem
This certificate expires on 2022-07-25.
These files will be updated when the certificate renews.
Certbot has set up a scheduled task to automatically renew this certificate in the background.

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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
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[4] To Update existing certificates manually, Do like follows.
# update all certs which has less than 30 days expiration
# if you'd like to update certs which has more than 30 days expiration, add [--force-renew] option

[root@dlp ~]#
certbot renew

[5] To Update existing certificates automatically, Start services for renewals which are included in Certbot package.
# Systemd Timer is included

[root@dlp ~]#
systemctl cat certbot-renew.timer

# /usr/lib/systemd/system/certbot-renew.timer
[Unit]
Description=This is the timer to set the schedule for automated renewals

[Timer]
OnCalendar=*-*-* 00/12:00:00
RandomizedDelaySec=12hours
Persistent=true

[Install]
WantedBy=timers.target

[root@dlp ~]#
systemctl enable --now certbot-renew.timer
[root@dlp ~]#
systemctl list-timers certbot-renew.timer

NEXT                        LEFT    LAST PASSED UNIT                ACTIVATES  >
Thu 2022-11-17 01:01:46 JST 7h left n/a  n/a    certbot-renew.timer certbot-ren>

1 timers listed.
Pass --all to see loaded but inactive timers, too.

# possible to specify pre or post commands of updating

[root@dlp ~]#
vi /etc/sysconfig/certbot
# line 17 : possible to specify pre-commands
# An example to stop the MTA before updating certs would be
# PRE_HOOK="--pre-hook 'systemctl stop postfix'"
PRE_HOOK=""

# line 29 : possible to specify post-commands
# An example to restart httpd would be:
# POST_HOOK="--post-hook 'systemctl restart httpd'"
POST_HOOK=""
[6] If you'd like to convert certificates to PKCS12 (PFX) format for Windows, do like follows.
[root@dlp ~]#
openssl pkcs12 -export -in fullchain.pem -inkey privkey.pem -out dlp_for_iis.pfx

Enter Export Password:     # set any export password
Verifying - Enter Export Password:
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