Sometimes I need to connect directly to the console of my virtual machines, typically this is usually when working with development or experimental VMs where SSH/RDP/VNC isn’t working for whatever reason, or when I’m installing a new OS entirely.
To view virtual machines using libvirt (by both KVM or Xen), you use the virt-viewer command, this launches a window and establishes a VNC or SPICE connection into the virtual machine.
Historically I’ve just run this by SSHing into the virtual machine host and then using X11 forwarding to display the virtual machine window on my laptop. However this performs really badly on slow connections, particularly 3G where it’s almost unusable due to the design of X11 forwarding not being particularly efficient.
However virt-viewer has the capability to run locally and connect to a remote server, either directly to the libvirt daemon, or via an SSH tunnel. To do the latter, the following command will work for KVM (qemu) based hypervisors:
virt-viewer --connect qemu+ssh://firstname.lastname@example.org/system vmnamehere
With the above, you’ll have to enter your SSH password twice – first to establish the connection to the hypervisor and secondly to establish a tunnel to the VM’s VNC/SPICE session – you’ll probably quickly decide to get some SSH keys/certs setup to prevent annoyance. ;-)
This performs way faster than X11 forwarding, plus the UI of virt-manager stays much more responsive, including grabbing/ungrabbing of the local keyboard/mouse, even if the connection or server is lagging badly.
If you’re using Xen with libvirt, the following should work (I haven’t tested this, but based on the man page and some common sense):
virt-viewer --connect xen+ssh://email@example.com/ vmnamehere
If you wanted to open up the right ports on your server’s firewall and are sending all traffic via a secure connection (eg VPN), you can drop the +ssh and use –direct to connect directly to the hypervisor and VM without port forwarding via SSH.