[nSLUG] rsh(1) as root

George N. White III gnwiii at gmail.com
Wed Feb 26 12:18:54 AST 2014


On Wed, Feb 26, 2014 at 9:08 AM, D G Teed <donald.teed at gmail.com> wrote:

> Whoops.  Noticed the dial up info later in the thread.
>
> Not sure how ntp would behave if the access to upstream
> server is intermittent.
>

Historically, the ntp "reference" implementation did not get along well
with intermittent connections, which is one of the reasons "chrony" was
created (see: <http://tldp.org/HOWTO/Clock-3.html>).   Chrony <
http://chrony.tuxfamily.org/> has worked well for me with dialup and
laptops in the past, and is even packaged for some distros, e.g., <
https://launchpad.net/ubuntu/+source/chrony>,
<https://packages.debian.org/sid/chrony>, <
https://fedoraproject.org/wiki/Features/ChronyDefaultNTP>, etc.

I think recent "ntp reference implementation" (protocol version 4, <
http://www.eecis.udel.edu/~mills/database/rfc/rfc5905.txt>) has made
improvements for transient connections.

 "Typical secondary servers and clients on fast LANs are within a few
hundred microseconds with poll intervals up to 1024 seconds, which was the
maximum with NTPv3. With NTPv4, servers and clients are precise within a
few tens of milliseconds with poll intervals up to 36 hours."



> On Wed, Feb 26, 2014 at 11:03 AM, D G Teed <donald.teed at gmail.com> wrote:
>
>>
>>
>>
>> On Wed, Feb 26, 2014 at 2:35 AM, Mike Spencer <mspencer at tallships.ca>wrote:
>>
>>>
>>> Working on host grody as root, I would like to do:
>>>
>>> grody-root% date -s `rsh nudel date`
>>>
>>> to set the date on grody to match that on nudel.
>>>
>>
>>
>> Is there a problem running ntpd, like no Internet?
>>
>> That is the industry standard way to have all system
>> times in sync.
>>
>
The industry standard relies excessively on old protocols.   I'm not sure
how many of the NTPv4 benefits
are actually available to home users using "pool" servers.

-- 
George N. White III <aa056 at chebucto.ns.ca>
Head of St. Margarets Bay, Nova Scotia
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