Ubuntu22.04 Server : Let's Encrypt , Apache・Mail SSL

1. Certificate Acquisition (Let's Encrypt)

1.1 advance preparation

①Enable mod_ssl

②Install client tool to obtain Let's Encrypt certificate

③Obtaining Certificates
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, perform step ④.
It is also assumed that the server on which the work is to be performed (the server with the FQDN from which the certificate is to be obtained) is accessible from the Internet at port 80.

# Use the directory under the public directory of the running Web server as a temporary area for authentication by specifying [--webroot].
# -w [document root] -d [FQDN from which you want to obtain a certificate]
# FQDN (Fully Qualified Domain Name) : Hostname. Domain name without abbreviation
#Document root is the one for the appropriate host definition if there are multiple host definitions for a virtual host
# Registration of e-mail address and agreement to terms of use are required for the first time only.
# Specify an email address to receive

Success when displaye ""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

④Obtaining a Let's Encrypt certificate when the web server is not running
It is a prerequisite that access to port 80 of the server is available.

#Use the simple Web server function by specifying [--standalone].
# -d [FQDN from which you want to obtain a certificate]
# 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

⑤Renewing 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

2. SSL/TLS (Let's Encrypt) configuration for Apache2

①Edit Apache2 SSL-related configuration files

②Reflecting and activating the configuration file

③http to https redirect

One of the following methods

3. Mail Server SSL/TLS(Let's Encrypt)

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.

If I stop the web server once and then do it, it succeeds as follows

3.2 Postfix Configuration

SMTP-Submission is [587/TCP], SMTPS is [465/TCP].

3.3 Dovecot Configuration

Allow Port 587 in firewall

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