I was wondering if anyone has had issues with the /dev/random RNG device being extremely slow on RHEL 6.5 when running as an VMware guest? When ssh-ing between servers the ssh login process hangs for many 10s of seconds (sometimes minutes) and key generation, using ssh-keygen, also hangs for ages. With some debugging I have narrowed the issue down to the processes waiting for /dev/random. Linking /dev/random (as per http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1036980) to /dev/urandom makes the processes run at the expected speeds.
I have an open case regarding the issue and I suggested that the link might be a good work-around (based on research into differences between /dev/random and urandom [e.g. http://www.2uo.de/myths-about-urandom/] but RH support are suggesting a hardware number generator. I've never used a hardware number generator but I suspect, in a non-vm environment, it is a straightforward to setup. I am, however, wondering if anyone has had experience in using one in a VMware environment with many guests per physical host? Can one hardware number generator feed multiple VMs?
(FYI: The RHEL 6 build in question has had the cc-eal4-config-rhel62 configuration applied which includes setting "SSH_USE_STRONG_RNG=12" in /etc/sysconfig/sshd, among other things!)
Thanks in advance,
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