2023

1.Obtain a certificate (Let's Encrypt) 1.1 advance preparation 1.Enable mod_ssl 2.Package management system Snappy installed Let's Encrypt's SSL certificate issuing tool "certbot" is recommended to be installed using "snap" after 2021, so install Snapd first. (It can also be installed using the conventional method with dnf or yum) 1.3 Obtain a Let's Encrypt Certificate It is assumed that a web server such as Apache httpd or Nginx is running. If the web server is not running on the server where the work is to be performed, follow the procedure below under "Obtaining a Let's Encrypt certificate when the web server is not running". It is also assumed that the server on which the work is to be performed (the server with the FQDN of the server from which you want to obtain the certificate) is accessible from the Internet at port 80. 2. SSL/TLS (Let's Encrypt) configuration for Apache2 ①Edit Apache2 SSL-related configuration files 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.