"Failed to subscribe" - poclbm over SSL - Ubuntu
After looking at the (quite old) source code of poclbm, there is a commented line that creates the SSL connection. Not sure it is the reason but I guess it doesn't support HTTPS in its last version.
I changed to DiabloMiner (I had to add my self-signed certificate using the InstallCert.java tool)

I can now mine over HTTPS. Next step is a pool...