I did a lot of research on this but still I am confused about how many certificates I need to self-sign for each of my services running on my private server. Here is the deal:
I am creating my own server on raspberry Pi (raspbian~debian) to run my own VPN server, a calendar/contact server (Darwin) and probably in the future an e-mail server and a web server.
First I have configured the openvpn server with easy RSA (client authenticates with key and password: following this tutorial). Of note, easy RSA seems to be related to openVPN.
Now, I need to set up the calendar server and force TLS connections for security. But I am not sure, if I need to self-sign another certificate or simply reuse old ones. This time client will only authenticate with a password. Do I a different self signed certificate for each service?
There is also the ssl-cert-snakeoil.key, which I could be using or not?