Bug#343085: exim4: Exim SMTP_AUTH hangs since today...

[Andreas Metzler]

On 2007-11-01 Marc Haber <mh+debian-packages at zugschlus.de> wrote:
> On Thu, Nov 01, 2007 at 10:46:38AM +0100, Andreas Metzler wrote:
[...]
> > Iirc gcrypt simply reads from /dev/urandom in this cae. This depletes
> > entropy the same way reading from /dev/random does.

> so, urandom first depletes the "real" entropy and then continues on a
> PRNG after using all real stuff?

I think so, yes:

ametzler at argenau:~$ cat /proc/sys/kernel/random/entropy_avail ; \
   time dd if=/dev/urandom bs=1M of=/dev/null count=5 ; \
   cat /proc/sys/kernel/random/entropy_avail
3256
5+0 Datensätze ein
5+0 Datensätze aus
5242880 Bytes (5,2 MB) kopiert, 0,916788 Sekunden, 5,7 MB/s

real   0m0.918s
user   0m0.000s
sys 0m0.920s
188

There might be some small amount reserved for /dev/random, I cannot
completely deplete /proc/sys/kernel/random/entropy_avail by
cat /dev/urandom > /dev/null
it does not get below something like 130.

cu andreas
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