Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754507AbZDGATX (ORCPT ); Mon, 6 Apr 2009 20:19:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751908AbZDGATK (ORCPT ); Mon, 6 Apr 2009 20:19:10 -0400 Received: from waste.org ([66.93.16.53]:54935 "EHLO waste.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751331AbZDGATJ (ORCPT ); Mon, 6 Apr 2009 20:19:09 -0400 Subject: Re: IRQF_SAMPLE_RANDOM question... From: Matt Mackall To: Sven-Haegar Koch Cc: Robin Getz , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Chris Peterson In-Reply-To: References: <200904061430.26276.rgetz@blackfin.uclinux.org> <1239044483.14392.55.camel@calx> Content-Type: text/plain Date: Mon, 06 Apr 2009 17:16:44 -0700 Message-Id: <1239063404.14392.118.camel@calx> Mime-Version: 1.0 X-Mailer: Evolution 2.24.5 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1839 Lines: 39 On Tue, 2009-04-07 at 00:09 +0200, Sven-Haegar Koch wrote: > On Mon, 6 Apr 2009, Matt Mackall wrote: > > > On Mon, 2009-04-06 at 14:30 -0400, Robin Getz wrote: > > > We have lots of embedded headless systems (no keyboard/mouse, no soundcard, no > > > video) systems with *no* sources of entropy - and people using SSL. > > > > I'd rather add a random_sample_network call somewhere reasonably central > > in the network stack. Then we can use the knowledge that the sample is > > network-connected in the random core to decide how to measure its > > entropy. The trouble with IRQF_SAMPLE_RANDOM is that many of its users > > are technically bogus as entropy sources in the current model. > > > > I'm eventually going to move the RNG away from the strict theoretical > > entropy accounting model to a more pragmatic one which will be much > > happier with iffy entropy sources, but that's a ways off. > > Btw, perhaps not the perfect question in this thread: > But what should we use to keep servers running without a hardware rng > available and without any external input besides the network? > After having ssh and openvpn die because of no random and having > the machines like dead and unreachable for me I use "ln -sf > /dev/urandom /dev/random", but that does not feel so good. It's fine so long as you're not wearing a tinfoil hat. In fact, as the /dev/random maintainer, I'd recommend it. Ted and I have recently been talking about revisiting the design of /dev/random to avoid these sorts of issues. -- http://selenic.com : development and support for Mercurial and Linux -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/