[ntp:questions] how to configure ntp for conditional use of servers, depending on my LAN status?

dar8757 at eml.cc dar8757 at eml.cc
Wed Jan 9 19:21:36 UTC 2013


hi,

i'm running ntp-4.2.6p5-3.10.1.x86_64 on linux/64.

i've a question about proper configuration/use of fallback on a roaming
laptop.

the laptop boots to a no-network configuration.  connection is
chosen/enabled as needed after KDE desktop launch ...

i'd like to configure ntpd.conf so that

(1) at machine boot, ntp starts up using the machine's local time, in
the absence of network access.  i think i'd use this:

	server 127.127.1.0
	fudge 127.127.1.0 stratum 10

(2) once network connection is made, if my IP is on my local LAN
(10.10.50.0/24), then use my local LAN's time server.  for that,

	server   ntp-server-f.q.d.n  iburst prefer
	restrict ntp-server-f.q.d.n

(3) if my IP is not on my LANB, then use some external servers.  e.g.,

	server clock.isc.org             iburst prefer
	restrict clock.isc.org

	server ntp1.sf-bay.org           iburst
	restrict ntp1.sf-bay.org


i'm not sure if/how to implement this conditional fallback 'logic' for
ntp's server selection.  reading the docs, i think stratum can be used
-- but really am not certain.  thought i should check before abusing
some servers inadvertently.

any guidance would be appreicated!

thanks,

daryl


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