Red Hat Training

A Red Hat training course is available for Red Hat Enterprise Linux

23.2. Remote management over TLS and SSL

You can manage virtual machines using TLS and SSL. TLS and SSL provides greater scalability but is more complicated than ssh (see Section 23.1, “Remote management with SSH”). TLS and SSL is the same technology used by web browsers for secure connections. The libvirt management connection opens a TCP port for incoming connections, which is securely encrypted and authenticated based on x509 certificates. In addition the VNC console for each guest virtual machine will be setup to use TLS with x509 certificate authentication.
This method does not require shell accounts on the remote machines being managed. However, extra firewall rules are needed to access the management service or VNC console. Certificate revocation lists can revoke users' access.
Steps to setup TLS/SSL access for virt-manager

The following short guide assuming you are starting from scratch and you do not have any TLS/SSL certificate knowledge. If you are lucky enough to have a certificate management server you can probably skip the first steps.

libvirt server setup
For more information on creating certificates, see the libvirt website, http://libvirt.org/remote.html.
Xen VNC Server
The Xen VNC server can have TLS enabled by editing the configuration file, /etc/xen/xend-config.sxp. Remove the commenting on the (vnc-tls 1) configuration parameter in the configuration file.
The /etc/xen/vnc directory needs the following 3 files:
  • ca-cert.pem - The CA certificate
  • server-cert.pem - The Server certificate signed by the CA
  • server-key.pem - The server private key
This provides encryption of the data channel. It might be appropriate to require that clients present their own x509 certificate as a form of authentication. To enable this remove the commenting on the (vnc-x509-verify 1) parameter.
virt-manager and virsh client setup
The setup for clients is slightly inconsistent at this time. To enable the libvirt management API over TLS, the CA and client certificates must be placed in /etc/pki. For details on this consult http://libvirt.org/remote.html
In the virt-manager user interface, use the 'SSL/TLS' transport mechanism option when connecting to a host.
For virsh, the URI has the following format:
  • qemu://hostname.guestname/system for KVM.
  • xen://hostname.guestname/ for Xen.
To enable SSL and TLS for VNC, it is necessary to put the certificate authority and client certificates into $HOME/.pki, that is the following three files:
  • CA or ca-cert.pem - The CA certificate.
  • libvirt-vnc or clientcert.pem - The client certificate signed by the CA.
  • libvirt-vnc or clientkey.pem - The client private key.