Re: Why does reading from /dev/urandom deplete entropy so much?

Theodore Tso
2007-12-04T22:04:04Z

On Tue, Dec 04, 2007 at 02:48:12PM -0600, Mike McGrath wrote:
> Alan Cox wrote:
>>> Here's the top 5:
>>>
>>> 266 28caf2c3-9766-4fe1-9e4c-d6b0ba8a0132
>>> 336 810e7126-1c69-4aff-b8b1-9db0fa8aa15a
>>> 402 c8dbb9d3-a9bd-4ba6-b92e-4a294ba5a95f
>>> 884 06e84493-e024-44b1-9b32-32d78af04039
>>> 931 e2b67e1d-e325-4740-b938-795addb45280
>>>
>>> The left number is times this month someone has submitted a profile with
>>> that UUID. If we take the last one as an example has come from over 800
>>> IP's in the last 20 days. It seems very unlikely that one person would
>>> find his way to 800 different IP's this month. Let me know if you'd
>>> like more.
>>>
> Background - Smolt runs this during its install:
>
> /bin/cat /proc/sys/kernel/random/uuid > /etc/sysconfig/hw-uuid
>
> For most users this would be run by the RPM %post scripts during install
> from anaconda. For some reason there are some UUID's (like those listed
> above) that come up more often then it seems they should if they are truly
> random.

Would this be by any chance using kickstart where there is no user
interaction, and no way of gathering entropy during the install process?
The random number generator isn't *magic* you know....

- Ted