How to install a letsencrypt SSL certificate on USERMIN

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#1 Sun, 11/18/2018 - 21:49
Luis Orlando

How to install a letsencrypt SSL certificate on USERMIN

Hello, I succesfully installed SSL certificates for Webmin (using my VPS address) and for the virtual server domains. So, I can access control panel Webmin/Virtualmin and websites with HTTPS and valid certificates.

However Usermin configuration SSL Encryption is using a self signed certificate, which is no longer accepted by Chrome and Edge. For what I understood, the webmail subdomain is automatically generated by Virtualmin on creation of a domain and associated to Usermin. So I have registered this subdomain on the DNS servers to be able to access the Usermin mail by internet. It worked. But when I try to access Usermin in , the browsers strongly advise to not proceed to the page.

In Usermin configuration SSL Encryption, I tried the button Copy Certificate from Webmin. It copied ok, but the certificate is not valid to the resulting in a worse browser alert. So I had to redefine a new self-signed certificate to Usermin.

Finally I went to Virtualmin and tried to generate a new SSL LetsEncrypt certificate for both and but with no success. The error message was: challenge did not pass: Fetching Invalid port in redirect target. Only ports 80 and 443 are supported, not 20000

I notice the main problem with SSL is in the login page (the page started by because once you enter Usermin, the padlock symbol appears in grey, (which is normal for the type of certificate from letsencrypt). So the critical moment when we have to put the password is just the moment that is uncovered by SSL.

Anyone has the solution to install a free certificate to the webmail sudomain? Thanks in advance!