sudo apt install certbot
certbot certonly --manual -d "*.itvro.com" --preferred-challenges dns --server https://acme-v02.api.letsencrypt.org/directory
其中--manual是表示手动方式验证，--perferred-challenges dns 则表示通过添加dns记录方式来验证域名所属真实，-d后用双引号圈出的部分则是泛域名。
IMPORTANT NOTES: - Congratulations! Your certificate and chain have been saved at: /etc/letsencrypt/live/itvro.com/fullchain.pem Your key file has been saved at: /etc/letsencrypt/live/itvro.com/privkey.pem Your cert will expire on 2021-09-13. 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" - Your account credentials have been saved in your Certbot configuration directory at /etc/letsencrypt. You should make a secure backup of this folder now. This configuration directory will also contain certificates and private keys obtained by Certbot so making regular backups of this folder is ideal. - 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 - We were unable to subscribe you the EFF mailing list because your e-mail address appears to be invalid. You can try again later by visiting https://act.eff.org.
后续只用在90天内用certbot renew 命令即可更新ssl证书。