Run an ssh shell to your server.
Run the following command:
cd /usr/local/src/ git clone https://github.com/letsencrypt/letsencrypt cd letsencrypt/ ./letsencrypt-auto --help all
Now login to your webmin admin panel at:
https://siteaddress:10000/ using root username.
Webmin configuration>SSL Encryption>Let’s Encrypt
It will show you:
Let's Encrypt is a free, automated, and open certificate authority that can be used to generate an SSL certificate for use by Webmin. Unfortunately, Let's Encrypt cannot be used on your system : The client command letsencrypt was not found on your system. Check the module configuration page to ensure you are using the correct path to the letsencrypt or letsencrypt-auto command.
Click on “module configuration”
and type in the path and click Save:
Configuration For module Webmin Configuration Full path to Let's Encrypt client command: /usr/local/src/letsencrypt/letsencrypt-auto
To enable SSL certificate for a site, Go to:
Virtualmin>Edit Virtual Server>Enabled features
Enable “SSL website enabled”
To Manage the certificate:
Virtualmin>Server configuration>Manage SSL certificates
Click on Letsencrypt and generate a new certificate