Date: Fri, 20 Aug 1999 20:46:10 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: Karl Denninger <karl@Denninger.Net> Cc: Jon Hamilton <hamilton@pobox.com>, Greg Black <gjb-freebsd@gba.oz.au>, Will Andrews <andrews@TECHNOLOGIST.COM>, Brett Glass <brett@lariat.org>, freebsd-security@FreeBSD.ORG Subject: Re: Securelevel 3 ant setting time Message-ID: <199908210346.UAA69386@apollo.backplane.com> References: <19990820214657.1605.qmail@alice.gba.oz.au> <19990821031948.09B2B1D@woodstock.monkey.net> <19990820222419.A83963@Denninger.Net>
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:> Absolutely untrue. There's value in keeping a group of machines
:> synchronized to _each other_, regardless of whether they're also
:> synchronized to the correct time. It is true that _for some purposes_
:> xntpd isn't all that useful in an intermittently-connected scenario,
:> but that doesn't render it completely devoid of any value.
:>
:> --
:> Jon Hamilton
:> hamilton@pobox.com
:
:Its not at all difficult to wire a GPS to be the "master" upon which XNTPD
:syncs.
:
:Without PPS output you won't be COMPLETELY accurate, but a few tens of
:Karl Denninger (karl@denninger.net) Web: childrens-justice.org
It's fairly easy to setup xntpd to use a local clock when it cannot
find a remote clock. As long as the two don't get too-badly out of sync
from each other xntpd can switch between them.
I use this trick all the time for machines which are not always
connected to the net. What you do is have one machine on your LAN
be a stratum 8 time source. You also set it up to connect to a real
time source on the internet. When you have internet connectivity the
real time source wins. When you don't, the local stratum 8 time source
wins. Simple!
See /usr/src/usr.sbin/xntpd/doc/README.refclock and other documentation
for more information.
-Matt
monitor no
broadcastclient no
broadcast (my LAN broadcast address)
restrict 0.0.0.0 notrust nomodify
server 127.127.1.0
fudge 127.127.1.0 stratum 8
restrict (someinternetip)
...
server (sameinternetip)
...
driftfile /var/run/ntp.drift
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