Debian 10 (buster) - メールサーバ SSL 設定！

# cd /etc/ssl/private

# openssl genrsa -aes128 -out server.key 2048
Generating RSA private key, 2048 bit long modulus
..................................+++
.......................................................+++
e is 65537 (0x10001)
Enter pass phrase for server.key:              # <= サーバ証明書用パスワード設定
Verifying - Enter pass phrase for server.key:  # <= サーバ証明書用パスワード確認入力

# openssl rsa -in server.key -out server.key
Enter pass phrase for server.key:              # <= サーバ証明書用パスワード応答
writing RSA key

# openssl req -new -days 3650 -key server.key -out server.csr
You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
------------------------------------------
Country Name (2 letter code) [AU]:JP                                    # <= 国の略名
State or Province Name (full name) [Some-State]:Shimane                 # <= 都道府県名
Locality Name (eg, city) []:Matsue                                      # <= 市区町村名
Organization Name (eg, company) [Internet Widgits Pty Ltd]:mk-mode.com  # <= サイト名（何でもよい）
Organizational Unit Name (eg, section) []:                              # <= 部署名（空でよい）
Common Name (e.g. server FQDN or YOUR name) []:mail.mk-mode.com         # <= ホスト名
Email Address []:postmaster@mk-mode.com                                 # <= 管理者メールアドレス

Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:      # <= 追加属性・空エンターでよい
An optional company name []:  # <= 追加属性・空エンターでよい

# openssl x509 -in server.csr -out server.crt -req -signkey server.key -days 3650
Signature ok
subject=C = JP, ST = Shimane, L = Matsue, O = mk-mode.com, CN = mail.mk-mode.com, emailAddress = postmaster@mk-mode.com
Getting Private key

# chmod 400 server.*

# SSL 用（最終行に追加）
smtpd_use_tls = yes
smtpd_tls_cert_file = /etc/ssl/private/server.crt
smtpd_tls_key_file = /etc/ssl/private/server.key
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache

# コメント解除
smtps     inet  n       -       y       -       -       smtpd
  -o syslog_name=postfix/smtps
  -o smtpd_tls_wrappermode=yes

# SSL 有効化
ssl = yes

# 証明書/鍵ファイル指定
ssl_cert = </etc/ssl/private/server.crt
ssl_key = </etc/ssl/private/server.key

# systemctl restart postfix
# systemctl restart dovecot

# ufw allow 465,993,995/tcp
Rule added

# ufw status
    :
465,993,995/tcp            ALLOW       Anywhere
    :