This discussion highlights the importance of making sure that hardware vendors
understand the need for working clocks that can be easily bootstrapped. In
addition to NTP radio clock receivers are ubiquitous, tiny and ridiculously
cheap. It is unconscionable that any consumer electronics are sold today that
boast a visible clock without including a radio clock receiver! This doesn't
fix the mountain of already deployed SOHO gear, but it is time for vendors that
know better (Cisco, Netgear, D-Link, etc.) to do the right thing.
I put entropy in a similar class of problem as radio clock receivers. There
are a number of reasonable sources for entropy that take up virtually no PCB
space and can be built with a few discrete components (thinking of quantum
effects between 2 transistor gates or zener breakdown noise on a zener diode).
Stronger entropy sources get expensive - but something that provides reasonable
entropy for light crypto should be available on SOHO class network gear.
On Sep 12, 2013, at 2:19 PM, robert bownes wrote:
Chiming in a bit late here, however, the availability of stratum 1 clocks and
stratum 2 class time data on non IP and/or non interconnected networks is now
so large, I question why one would run NTP outside of the building in many
cases, certainly in an enterprise of any size.
A 1pulse per second aligned to GPS is good to a few ns. Fairly
straightforward to plug into even a OpenWrt type of router. Turn on the pps
in NTP on the router and you are good to go.
On Tue, Sep 10, 2013 at 6:45 PM, Evan Hunt <each(_at_)isc(_dot_)org> wrote:
On Tue, Sep 10, 2013 at 05:59:52PM -0400, Olafur Gudmundsson wrote:
My colleagues and I worked on OpenWrt routers to get Unbound to work
there, what you need to do is to start DNS up in non-validating mode wait
for NTP to fix time, then check if the link allows DNSSEC answers
through, at which point you can enable DNSSEC validation.
That's roughly what we did with BIND on OpenWrt/CeroWrt as well. We
also discussed hacking NTP to set the CD bit on its initial DNS queries,
but I don't think any of the code made it upstream.
My real recommendation would be to run an NTP pool in an anycast cloud of
well-known v4 and v6 addresses guaranteed to be reliable over a period of
years. NTP could then fall back to those addresses if unable to look up the
server it was configured to use. DNS relies on a well-known set of root
server addresses for bootstrapping; I don't see why NTP shouldn't do the
same.
(Actually... the root nameservers could *almost* provide a workable time
tick for bootstrapping purposes right now: the SOA record for the root
zone encodes today's date in the serial number. So you do the SOA lookup,
set your system clock, attempt validation; on failure, set the clock an
hour forward and try again; on success, use NTP to fine-tune. Klugey! :) )
--
Evan Hunt -- each(_at_)isc(_dot_)org
Internet Systems Consortium, Inc.
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