Hello,

Is there a way to install SSL-Certificates for the master- and all slavesites?

In our installation (Plesk 12.5.x) the slave-domains are aliases to the main domain and an ssl-certificate can only be installed for the main domain, but our customer wishes to also protect the slave sites.

Can this be done? Does anyone have a solution for this?
The only solution I found would be to have a certificate that covers multiple domains, but they are quite expensive.

Kind regards

-Stephan

Look into Let's Encrypt. It's a free SSL.

Let's Encrypt Homepage

Let's Encrypt Plesk Extensions

What ever came of this? Were you able to figure out a way to do it?

One way would be able to buy a wildcard SSL and set up any secure pages to use the subdomain URL of that slave site.

Curious how you might have handled it?

When using cPanel, it is not required to buy a SSL but you can probably use the free AutoSSL.

The cPanel autoSSL works for the addon domain and specific subdomain (not wildcard subdomains). So if you need a SSL for a subdomain, you have to define it explicitly to allow the WHM/cPanel auto SSL create the SSL certificate for the domains and subdomains.

This require that the autoSSL is enabled for the cPanel account.

So if this site has a master (master.com) and two slave sites, slave1.com and slave2.com, plus a third site to manage shared users, users.com, would the autoSSL be able to secure all four domains, or if not, what would we need to purchsse and configure to secure them?

AutoSSL is NOT related to JMS.
AutoSSL is a cPanel feature that allow a domain or a subdomain have a free SSL certificate.
So check your WHM autoSSL in case where it would fails for your domain and subdomain.