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Get SSL Certificate (Let's Encrypt)2021/08/19

 
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 package 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:~#
apt -y install certbot
[2] Get certificates.
It needs Web server like Apache httpd or Nginx must be running 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 dlp.srv.world]
root@dlp:~#
certbot certonly --webroot -w /var/www/html -d dlp.srv.world

Saving debug log to /var/log/letsencrypt/letsencrypt.log
Plugins selected: Authenticator standalone, Installer None
# for only initial using, register your email address and agree to terms of use
# specify valid email address
Enter email address (used for urgent renewal and security notices)
 (Enter 'c' to cancel): root@srv.world 

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
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?
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
agree to the terms of use
(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 dlp.srv.world
Performing the following challenges:
http-01 challenge for dlp.srv.world
Waiting for verification...
Cleaning up challenges
Subscribe to the EFF mailing list (email: root@srv.world).

IMPORTANT NOTES:
 - Congratulations! Your certificate and chain have been saved at:
   /etc/letsencrypt/live/dlp.srv.world/fullchain.pem
   Your key file has been saved at:
   /etc/letsencrypt/live/dlp.srv.world/privkey.pem
   Your certificate will expire on 2021-11-17. To obtain a new or
   tweaked version of this certificate in the future, simply run
   certbot again. To non-interactively renew *all* of your
   certificates, run "certbot renew"
 - 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 [Congratulations] 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 possible 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]

# ⇒ [-d srv.world -d mail.srv.world]
root@dlp:~#
certbot certonly --standalone -d mail.srv.world

Saving debug log to /var/log/letsencrypt/letsencrypt.log
Plugins selected: Authenticator standalone, Installer None
Requesting a certificate for mail.srv.world
Performing the following challenges:
http-01 challenge for mail.srv.world
Waiting for verification...
Cleaning up challenges

IMPORTANT NOTES:
 - Congratulations! Your certificate and chain have been saved at:
   /etc/letsencrypt/live/mail.srv.world/fullchain.pem
   Your key file has been saved at:
   /etc/letsencrypt/live/mail.srv.world/privkey.pem
   Your certificate will expire on 2021-11-17. To obtain a new or
   tweaked version of this certificate in the future, simply run
   certbot again. To non-interactively renew *all* of your
   certificates, run "certbot renew"
 - 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
[4] For Updating existing certs manually, use [renew] subcommand.
To run [renew] subcommand, all certs which have less than 30 days expiration are updated.
If you'd like to update certs which has more than 30 days expiration, add [--force-renew] option.
However, [certbot] package has systemd timer, so it does not need to run it manually.
# systemd timer script is included in Certbot package

root@dlp:~#
systemctl status certbot.timer

*  certbot.timer - Run certbot twice daily
     Loaded: loaded (/lib/systemd/system/certbot.timer; enabled; vendor preset:>
     Active: active (waiting) since Thu 2021-08-19 15:55:39 JST; 1min 0s ago
    Trigger: Fri 2021-08-20 01:24:00 JST; 9h left
   Triggers: * certbot.service

root@dlp:~#
systemctl list-timers certbot.timer --no-pager

NEXT            LEFT    LAST             PASSED    UNIT          ACTIVATES
Fri 2021-08-20… 9h left Thu 2021-08-19 … 21min ago certbot.timer certbot.service

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

# [renew] is run 2 times every day like follows by default

root@dlp:~#
systemctl cat certbot.timer

# /lib/systemd/system/certbot.timer
[Unit]
Description=Run certbot twice daily

[Timer]
OnCalendar=*-*-* 00,12:00:00
RandomizedDelaySec=43200
Persistent=true

[Install]
WantedBy=timers.target

root@dlp:~#
systemctl cat certbot.service

# /lib/systemd/system/certbot.service
[Unit]
Description=Certbot
Documentation=file:///usr/share/doc/python-certbot-doc/html/index.html
Documentation=https://certbot.eff.org/docs
[Service]
Type=oneshot
ExecStart=/usr/bin/certbot -q renew
PrivateTmp=true

# for manual update, do like follows

root@dlp:~#
certbot renew

[5] 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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