Re: Seeding /dev/random not working

From: M Macnair
Date: Tue May 29 2007 - 12:44:50 EST


On 29 May 2007 18:58:59 +0200, Andi Kleen <andi@xxxxxxxxxxxxxx> wrote:
"M Macnair" <mmacnair@xxxxxxxxx> writes:
>
> Many distros ship with an init script that saves and restores the
> entropy pool on startup and shutdown. The bit that interests me that
> is called on startup is (my comments):
> if [ -f $random_seed ]; then
> cat $random_seed >/dev/urandom # should seed the pool
OA
Writing doesn't actually work; to get real accounted entropy for /dev/random
you need to use a special ioctl. I ran into this problem some years ago
and ended up writing http://www.muc.de/~ak/rndfeed.c

-Andi

If this doesn't work, then it seems to me as though all the
debian-esque distros that use equivalents of the above script are
wasting their time, and the man page recommending that technique (man
4 random) is also wrong. Is that interpretation correct?

Mike
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