On Mon, Feb 10, 2014 at 20:58, Jean-Philippe Ouellet wrote: > 2) I suspect that seeding your PRNG with data sent in the clear > isn't a great idea in the first place. > > 3) If you're netbooting anyway, by the time you actually fetch the > kernel you've already done a bunch of network operations. Wouldn't > timing information from that be safer than some seed sent in the > clear?
True, but if everything goes according to plan, all the inputs to the random device are mixed together. Knowing those inputs reduces (eliminates) their value, but doesn't compromise the design itself. The other inputs are still unknown. Also consider anybody in a position to see random.seed is going to be in a position to see /etc/ssh/ host keys, which is a far more serious compromise. Don't let the naughty people sniff your NFS traffic. > 4) Could just be my lack of understanding, but I'm not sure that > serving /etc/random.seed via NFS is a good idea. Wouldn't it need > to be the same as the NFS server's? As far as I can tell, exports(5) > doesn't allow you to export some arbitrary (not /etc) tree and have > it appear to others as /etc. You don't have to export the server's /. Indeed this won't even work if they're different architectures. The typical approach is to export a separate partition from the server. There are some details in the diskless man page. It is true that multiple clients will share the same random.seed unless you have multiple /etc directories configured.
