How can I use rsync on my virtual machine to back up a remote linux system?

I want to back up a remote Linux Ubuntu system using rsync. Therefore I set up a virtual machine with Virtualbox. I installed Linux Ubuntu on the virtual machine. I can ping the remote server with this OS on the virtual machine. The problem is that I can not ping the Linux on the virtual machine so that I can use the rsync command to do the required backup. 

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