From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Thompson, David" Subject: bug#23605: /dev/urandom not seeded across reboots Date: Tue, 24 May 2016 13:29:44 -0400 Message-ID: References: <20160523175832.GA10646@jasmine> <87shx8j5qm.fsf@T420.taylan> <20160524161617.GC29516@jasmine> <20160524172329.GA5216@jasmine> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Return-path: Received: from eggs.gnu.org ([2001:4830:134:3::10]:46977) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b5G9g-0000ak-Jg for bug-guix@gnu.org; Tue, 24 May 2016 13:30:09 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1b5G9b-0002iV-CO for bug-guix@gnu.org; Tue, 24 May 2016 13:30:07 -0400 Received: from debbugs.gnu.org ([208.118.235.43]:52533) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1b5G9b-0002hg-6s for bug-guix@gnu.org; Tue, 24 May 2016 13:30:03 -0400 Received: from Debian-debbugs by debbugs.gnu.org with local (Exim 4.84_2) (envelope-from ) id 1b5G9a-0008DT-R5 for bug-guix@gnu.org; Tue, 24 May 2016 13:30:02 -0400 Sender: "Debbugs-submit" Resent-Message-ID: In-Reply-To: <20160524172329.GA5216@jasmine> List-Id: Bug reports for GNU Guix List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-guix-bounces+gcggb-bug-guix=m.gmane.org@gnu.org Sender: "bug-Guix" To: Leo Famulari Cc: 23605@debbugs.gnu.org On Tue, May 24, 2016 at 1:23 PM, Leo Famulari wrote: > On Tue, May 24, 2016 at 12:26:29PM -0400, Thompson, David wrote: >> On Tue, May 24, 2016 at 12:16 PM, Leo Famulari wrote= : >> > On Tue, May 24, 2016 at 09:05:21AM +0200, Taylan Ulrich Bay=C4=B1rl=C4= =B1/Kammer wrote: >> >> Leo Famulari writes: >> >> > Does anyone have advice about the service? Am I wrong that we need = to >> >> > seed /dev/urandom to make it work properly? >> >> >> >> Yes, this is necessary under Linux if you want urandom to be random >> >> enough immediately after boot, and all the distros do it as part of >> >> their init. >> >> >> >> There's also an interesting implication here about the very first tim= e >> >> you boot the system and don't have a urandom seed file from the last >> >> shutdown yet. I don't know how this is typically handled, given that >> >> for instance it's quite possible that a user might generate SSH keys >> >> shortly after their first boot of a system. >> > >> > When I boot a GuixSD VM for the first time [0], it requires me to danc= e >> > on the keyboard until it has collected ~200 bits of entropy. I assumed >> > this is to properly bootstrap the CSPRNG in /dev/urandom, but I'm not >> > sure. >> >> This is just an annoying feature of GNU lsh. I want to switch my >> machines to OpenSSH sometime, partly due to this. > > Well, it seems that this feature might be protecting us against using > weak SSH session keys on first boot, if it's doing what I think it's > doing... It impedes automated provisioning of servers, which OpenSSH does not do. - Dave