Even thou Crashplan is a GUI based application there is no problem using it on a X-less (Headless) Linux server. you install it in the console and then connect to it from your Mac or windows machine using a ssh tunnel. Ssh tunneling basically forwards a connection from a local port on your computer to a port on a remote machine and is as easy to setup as making a ssh to your server.
Here is an example:
ssh -L 4200:localhost:4243This connects to the remote server as a regular SSH connection, but as long as you are logged in it will also keep a "port forwarding" from your localmachine on port 4200 to the remote host´s 4243 port.
Then all you have to do is to locate CrashPlans ui.properties file and add this line:
servicePort=4200When you start Crashplan locally on your computer, it will connect to localhost:4200. Your SSH connection will then forward the connection (undetected by Crashplan client) to the remote host´s crashplan service.
Just remember to comment out the servicePort line after you are done configuring the host.