[ale] possibility of running an NTP server

[Ron Frazier]

Hi Guys,

Hope you had a Merry Christmas and a Happy start to the new year.  While 
I'll admit that I haven't read all the 200+ messages on the list since 
vacation, I do have a new question I wanted to ask.  I'll go ahead and 
give the caveat that this falls into the category of something that I 
might like to do but may never get around to, or it may be too costly, etc.

For some time, I've had an amateur interest the science of timekeeping.  
Haven't really pursued it.  I've been recently been doing research into 
time servers, and time signals, etc.  I used some Christmas money to get 
a solar atomic watch made by Casio and a couple of solar atomic wall 
clocks made by LaCrosse Technology.  They're very cool.  They receive 
the WWVB time signal from the NIST in Colorado.  They charge themselves, 
and set themselves.  I never have to set them, and I never have to 
replace the batteries, at least until the rechargeable batteries in them 
die, and as long as I give them an adequate dose of light.  The problem 
with the WWVB signal is that it usually doesn't work in the daytime due 
to the ionosphere and other interference.  So, I was trying to 
synchronize my watch and one clock today and they just refused to 
receive the signal enough to work.  Hopefully, they'll pick it up in the 
middle of the night.

In my research, I ran across the NTP Pool project at 
http://www.pool.ntp.org/en/ .  They and people associated with them 
operate a pool of 2904 servers for the purpose of providing NTP time 
service.  They also say, on their site, that they need more servers.  
So, the thought crossed my mind that I could operate an NTP server and 
associate with the pool.  That brings up a bunch of questions.

As I understand it, the time servers / devices are divided into Stratum 
levels.  Stratum 0 devices are the actual atomic clocks, etc. that run 
the world's timekeeping systems at the highest level.  Stratum 1 devices 
are connected to Stratum 0 devices directly, not through the internet.  
I presume that the computer running the radio transmitter at NIST in 
Colorado is a Stratum 1 device.  Stratum 2 devices are more numerous and 
are connected to Stratum 1 devices through the internet.  Stratum 3 
devices are more numerous and are connected to Stratum 2 devices through 
the internet.  This is a useful article on Wikipedia: 
http://en.wikipedia.org/wiki/Network_Time_Protocol .

This document: http://support.ntp.org/bin/view/Servers/WebHome provides 
access to a list of time servers.

This document: http://support.ntp.org/bin/view/Servers/RulesOfEngagement 
shows the rules for usage of the servers.  It discourages use of Stratum 
1 servers except where Stratum 2 servers are the clients and where those 
servers provide time synchronization to a large number of lower level 
users.  Thus, I'm presuming that, if I were to operate an NTP server, 
mine would be considered a Stratum 3 server and mine would primarily 
reference Stratum 2 servers to get time data.  So, I would set the 
configuration file on my system to have the NTP daemon reference a 
number of Stratum 2 servers for time synchronization data.  As I 
understand it, each network hop adds up to about 150 mS of delay, so I 
would expect my Stratum 3 server to have it's time delayed about 300 mS 
from the upline Stratum 1 source.  Since the Stratum 1 servers are 
connected directly to the atomic clocks, etc, I would expect that the 
time on the Stratum 1 devices differs very little from the true time.

According to this page: http://www.pool.ntp.org/en/join.html regarding 
joining the NTP pool, Stratum 3 or Stratum 4 servers can join the pool.

Assuming I wanted to set up an NTP server, that brings up yet more 
questions.  Can I do it on a residential 3 Mbps up / 16 Mbps down 
connection from Comcast?  Do I really have to have a static IP or can a 
Dynamic DNS name suffice?

Assuming the answers to the last two are yes and yes, I'm assuming I 
would connect the NTP server outside my home hardware firewall / 
router.  So, could I connect things as follows (assume TCP/IP v4):

Internet --> Cable Modem --> 4 Port Router (WAN Port)

The router provides DHCP service to my internal LAN.

4 Port Router (Port 1) --> NTP Server - Set this port to reserve the 
same internal LAN IP for this server every time by MAC address.  Set up 
a port forwarding rule to forward incoming NTP packets to this IP.
4 Port Router (Port 2) --> My normal other internal computers
4 Port Router (Wireless) --> My normal other internal computers

Assuming all this works, the NTP server will essentially be outside the 
firewall.  So, what do I need to run the server, an old Pentium 1 300 
MHz laptop, an old 486 laptop, a router with reflashed firmware, Ubuntu, 
a stand alone NTP utility booting off of a CD?  All I would want this 
particular device to do is run NTP and be accessible to me on the 
Internal LAN for maintenance and configuration.

I know the question is a bit vague, and spread out, but any light you 
guys can shed on the topic is appreciated.  Even though I might not be 
able to set up and run a server, I love to learn about these things 
regardless.

Thanks in advance.

Sincerely,

Ron


-- 

(PS - If you email me and don't get a quick response, you might want to
call on the phone.  I get about 300 emails per day from alternate energy
mailing lists and such.  I don't always see new messages very quickly.)

Ron Frazier

770-205-9422 (O)   Leave a message.
linuxdude AT c3energy.com