[winswitch] How to connect using ssh when I have to specify the private key file?

[Heng Zhou]

Hi, I tried to use xpra on Amazon EC2 ubuntu instance. But to connect to
this instance using ssh, Amazon requires that we have to specify the
private key (identity) file using -i parameter, and this is the only way to
connect to it through ssh. So how should I write the ssh parameter in the
"xpra attach" command line for which it seems that only
ssh:SERVERUSERNAME at SERVERHOST:100 form is allowed.

As an alternative, if I plan to connect to EC2 instance using TCP, how to
let the xpra server specify the TCP port?

Thanks for any help.