Server9

libvirtd

The connection string for virsh is: qemu+ssh://root@server9.cluster.zentralwerk.org/system.

If you want to use a GUI instead, virt-manager is a good option. You can connect under File > Add Connection. Then choose QEMU/KVM as the Hypervisor, connect via ssh, root as username and server9.cluster.zentralwerk.org as host and click Connect.