Increasing the entropy in virtual machines
Access to high-quality random numbers is important for the proper functioning of an operating system, in particular for its security related
components and applications. In case the rate by which
/dev/random provides random numbers within a VM is not sufficient, users can install
rngd service to generate random numbers from the underlying processor's Digital Random Number Generator (DRNG):
$ yum install -y rng-tools ... $ systemctl start rngd
This will increase the rate at which random numbers are available from
/dev/random, but avoid the lower-quality pseudo-random numbers from
More information on
rngd can be found in the RedHat Security guides for
CC7 / RHEL7.
At the moment, the CERN cloud service does not configure the export of random numbers from the host to the guests (as implemented by the
virtio_rng driver, for instance).