Setting up multiple SSL Certificates on a single IP address is possible, and acceptable on nearly all browsers, thanks to Server Name Identification (SNI).
SNI sends a site visitor the certificate that matches the requested server name – great! No more need to buy extra IP addresses.
I set this up on a Ubuntu 12.04 server and it was quite straightforward. The process I followed was:
1) set up the server and virtual hosts (see first link below)
2) generate a certificate request (CSR) (see second link below) – make sure you include www. before the domain name
3) go over to https://cheapsslsecurity.com and buy a RapidSSL for about £5.
— there is a process whereby they email you a link to generate your certificate
— to generate your cert you need the CSR you created earlier
— NB: for ‘verification’ you won’t be able to use the email address you get the certificate mailed to, so I chose to use ‘file verification’ where I uploaded a file to the server to verify
— Also note, if you included www. in the domain name while creating the CSR your cert with cover both with or without www.
This first reference is great for understanding SNI and how to set up your virtual hosts for multiple SSL. Note, this link is for a self-signed cert, so you need to generate a request (CSR) instead… see next link:
Also for further cross-references: