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Update HowTo on using the pool #218

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Update HowTo to on using the pool
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215 changes: 120 additions & 95 deletions docs/ntppool/en/use.html
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[% page.title = 'How do I setup NTP to use the pool?' %]

<div class="block">
<h3 id="use">How do I use pool.ntp.org?</h3>

<p>
If you just want to synchronise your computers clock to the network, the configuration file (for the ntpd program from the <a href="http://www.ntp.org">ntp.org distribution</a>, on any supported operating system - <b>Linux, *BSD, Windows and even some more exotic systems</b>) is really simple:
</p>

[% INCLUDE "ntppool/use/sample-config.html" %]

<p>
The 0, 1, 2 and 3.pool.ntp.org names point to a random set of servers that will
change every hour. Make sure your computer's clock is set to something
sensible (within a few minutes of the 'true' time) - you could use <code>ntpdate
pool.ntp.org</code>, or you could just use the <code>date</code> command and set it
to your wristwatch. Start ntpd, and after some time (this could take as long as
half an hour!), <code>ntpq -pn</code> should output something like:
</p>

[% INCLUDE "ntppool/use/sample-ntpq.html" %]

<p>
The IP addresses will be different, because you've been assigned random
timeservers. The essential thing is that one of the lines starts with an
asterisk (<code>*</code>), this means your computer gets the time from the internet
- you'll never have to worry about it again!
</p>
<p>
Looking up <code>pool.ntp.org</code> (or <code>0.pool.ntp.org</code>,
<code>1.pool.ntp.org</code>, etc) will usually return IP addresses for servers
in or close to your country. For most users this will give the best results.
</p>

<p>You can also use the <a href="/zone/@">continental zones</a> (For example
<a href="/zone/europe">europe</a>,
<a href="/zone/north-america">north-america</a>,
<a href="/zone/oceania">oceania</a>
or <a href="/zone/asia">asia</a>.pool.ntp.org),
and a country zone (like
ch.pool.ntp.org in Switzerland) - for all these zones, you can again use the 0,
1 or 2 prefixes, like 0.ch.pool.ntp.org. Note, however, that the country zone
might not exist for your country, or might contain only one or two timeservers.
</p>
<p>
If you're using <b>a recent Windows version</b>, you can use the ntp
client that is built into the system. As administrator enter</p>
<h3 id="use">How do I use pool.ntp.org?</h3>

<p>
If you just want to synchronise your computers clock to the network, the configuration file (for the ntpd program from the <a href="http://www.ntp.org">ntp.org distribution</a>, on any supported operating system - <b>Linux, *BSD, Windows and even some more exotic systems</b>) is really simple:
</p>

[% INCLUDE "ntppool/use/sample-config.html" %]

<p>
The 0, 1, 2 and 3.pool.ntp.org names point to a random set of servers that will
change every hour. Make sure your computer's clock is set to something
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sensible (within a few minutes of the 'true' time) - you could use <code>ntpdate
2.pool.ntp.org</code>, or you could just use the <code>date</code> command and set it
to your wristwatch. Start ntpd, and after some time (this could take as long as
half an hour!), <code>ntpq -pn</code> should output something like:
</p>

[% INCLUDE "ntppool/use/sample-pool-ntpq.html" %]

<p>
The IP addresses will be different, because you've been assigned random
timeservers. The essential thing is that one of the lines starts with an
asterisk (<code>*</code>), this means your computer gets the time from the internet
- you'll never have to worry about it again!
</p>
<p>On more recent Linux operating systems, time setting has been delegated to
<code>systemd</code>. You can use <code>timedatectl</code> to set the time:
</p>

[% INCLUDE "ntppool/use/sample-timedatectl.html" %]

<p>
On RedHat et al. (Fedora, CentOS, etc.) <a href="https://chrony.tuxfamily.org/"><code>chronyd</code></a>
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has replaced <code>ntpd</code> as the default NTP client (and server). With respect
to the time source configuration it uses the same syntax as <code>ntpd</code>,
so you can use the example above. Usually, the shipped configuration comes with a
a sensible default using the distribution's vendor pool and doesn't need any adjusting at all.
For checking on the synchronization status, use <code>chronyc -n sources</code>.
The output is similar to <code>ntpq</code> including the asterisk designating
the current time source.
</p>
<p> On older systems, <code>ntpd</code> may not support the pool configuration described
above. The following should work with legacy <code>ntpd</code> versions:
</p>

[% INCLUDE "ntppool/use/sample-ntpq.html" %]

<p>
Looking up <code>2.pool.ntp.org</code> (or <code>0.pool.ntp.org</code>,
<code>1.pool.ntp.org</code>, etc) will usually return IP addresses for servers
in or close to your country. For most users this will give the best results.<br>
<strong>Note:</strong> For historical reasons only <code>2.pool.ntp.org</code> will
return both IPv4 <emphasize>and</emphasize> IPv6 addresses. The other names only
return IPv4 addresses.
</p>

<p>You can also use the <a href="/zone/@">continental zones</a> (For example
<a href="/zone/europe">europe</a>,
<a href="/zone/north-america">north-america</a>,
<a href="/zone/oceania">oceania</a>
or <a href="/zone/asia">asia</a>.pool.ntp.org),
and a country zone (like
ch.pool.ntp.org in Switzerland) - for all these zones, you can again use the 0,
1 or 2 prefixes, like 0.ch.pool.ntp.org. Note, however, that the country zone
might not exist for your country, or might contain only one or two timeservers.
</p>
<p>
If you're using <b>a recent Windows version</b>, you can use the ntp
client that is built into the system. As administrator enter</p>
<pre class="code">
w32tm /config /syncfromflags:manual /manualpeerlist:"0.pool.ntp.org 1.pool.ntp.org 2.pool.ntp.org 3.pool.ntp.org"
w32tm /config /syncfromflags:manual /manualpeerlist:"2.pool.ntp.org 3.pool.ntp.org 0.pool.ntp.org 1.pool.ntp.org"
</pre>
<p>
at the command prompt. This will work on Windows 2003 and newer. If you use an
older version of windows you can try</p>
<p>
at the command prompt. This will work on Windows 2003 and newer. If you use an
older version of windows you can try</p>
<pre class="code">
net time /setsntp:"0.pool.ntp.org 1.pool.ntp.org 2.pool.ntp.org"
net time /setsntp:"2.pool.ntp.org 3.pool.ntp.org 0.pool.ntp.org"
</pre>
<p>
The same can be achieved by, as administrator, right-clicking the clock in the taskbar,
selecting 'Adjust Date/Time' and entering the server name in the 'Internet Time' tab.
</p>
<p>
The same can be achieved by, as administrator, right-clicking the clock in the taskbar,
selecting 'Adjust Date/Time' and entering the server name in the 'Internet Time' tab.
</p>

<p>
Meinberg made a port of the <a href="http://www.meinberg.de/english/sw/ntp.htm">ntp daemon for windows</a>.
</p>
<p>
Meinberg made a port of the <a href="http://www.meinberg.de/english/sw/ntp.htm">ntp daemon for windows</a>.
</p>

<p>
If your Windows system is part of a domain, you might not be able to independently update your computer time.
<p>
If your Windows system is part of a domain, you might not be able to independently update your computer time.

For more information about setting the time on windows, see <a href="http://technet.microsoft.com/en-us/library/cc773013%28WS.10%29.aspx">How Windows Time Service Works</a>.
</p>
For more information about setting the time on windows, see <a href="http://technet.microsoft.com/en-us/library/cc773013%28WS.10%29.aspx">How Windows Time Service Works</a>.
</p>
</div>

<div class="block">
<h3 id="notes">Additional Notes</h3>
<h3 id="notes">Additional Notes</h3>

<p><span class="hook">Consider if the NTP Pool is appropriate
for your use</span>. If business, organization or human life
Expand All @@ -86,45 +111,45 @@ <h3 id="notes">Additional Notes</h3>
We recommend time servers from
<a href="http://www.meinbergglobal.com/english/products/ntp-time-server.htm">Meinberg</a>,
but you can also find time servers from
<a href="http://www.endruntechnologies.com/NTP-Servers/gps-cdma-ntp.htm">End Run</a>,
<a href="http://spectracom.com/products-services/precision-timing#anchor-2172">Spectracom</a>
<a href="https://endruntechnologies.com/products/ntp-time-servers">End Run</a>,
<a href="https://www.orolia.com/solution/timing-and-synchronization/">Orolia</a>
and many others.
</p>

<p><span class="hook">If you have a static IP address and a reasonable Internet connection</span> (bandwidth
is not so important, but it should be stable and not too highly loaded), please
consider donating your server to the server pool. It doesn't cost you more than
a few hundred bytes per second traffic, but you help this project survive.
Please <a href="/join.html">read the joining page</a> for more information.
</p>

<p><span class="hook">If your Internet provider has a timeserver</span>, or if you know of a good timeserver
near you, you should use that and not this list - you'll probably get better
time and you'll use fewer network resources. If you know only one timeserver
near you, you can of course use that and two from pool.ntp.org or so.</p>

<p><span class="hook">It can rarely happen that you are assigned the same timeserver twice</span> -
just restarting the ntp server usually solves this problem. If you
use a country zone, please note that it may be because there is only
one server known in the project - better use a continental zone in
that case. You can <a href="/zone">browse the zones</a> to see how
many servers we have in each zone.</p>

<p><span class="hook">Be friendly</span>. Many servers are provided by volunteers, and almost all time
servers are really file or mail or webservers which just happen to also run ntp.
So don't use more than four time servers in your configuration, and don't play
tricks with <code>burst</code> or <code>minpoll</code> - all you will gain is extra
<p><span class="hook">If you have a static IP address and a reasonable Internet connection</span> (bandwidth
is not so important, but it should be stable and not too highly loaded), please
consider donating your server to the server pool. It doesn't cost you more than
a few hundred bytes per second traffic, but you help this project survive.
Please <a href="/join.html">read the joining page</a> for more information.
</p>

<p><span class="hook">If your Internet provider has a timeserver</span>, or if you know of a good timeserver
near you, you should use that and not this list - you'll probably get better
time and you'll use fewer network resources. If you know only one timeserver
near you, you can of course use that and two from pool.ntp.org or so.</p>

<p><span class="hook">It can rarely happen that you are assigned the same timeserver twice</span> -
just restarting the ntp server usually solves this problem. If you
use a country zone, please note that it may be because there is only
one server known in the project - better use a continental zone in
that case. You can <a href="/zone">browse the zones</a> to see how
many servers we have in each zone.</p>

<p><span class="hook">Be friendly</span>. Many servers are provided by volunteers, and almost all time
servers are really file or mail or webservers which just happen to also run ntp.
So don't use more than four time servers in your configuration, and don't play
tricks with <code>burst</code> or <code>minpoll</code> - all you will gain is extra
load on the volunteer time servers.</p>

<p><span class="hook">Make sure that the <i>time zone configuration</i> of your computer is correct</span>.
ntpd itself does not do anything about the time zones, it just uses UTC
internally.</p>
<p><span class="hook">Make sure that the <i>time zone configuration</i> of your computer is correct</span>.
ntpd itself does not do anything about the time zones, it just uses UTC
internally.</p>

<p><span class="hook">If you are synchronising a network to pool.ntp.org</span>, please set up one of your
computers as a time server and synchronize the other computers to that one.
(you'll have some reading to do - it's not difficult though. And there's always
the <a href="news:comp.protocols.time.ntp">comp.protocols.time.ntp newsgroup</a>.)</p>
<p><span class="hook">If you are synchronising a network to pool.ntp.org</span>, please set up one of your
computers as a time server and synchronize the other computers to that one.
(you'll have some reading to do - it's not difficult though. And there's always
the <a href="https://community.ntppool.org/">community</a> to help out.)</p>

<p class="thanks">At this point, I'd like to thank those donating their time and timeservers to
this network.</p>
<p class="thanks">At this point, I'd like to thank those donating their time and timeservers to
this network.</p>
</div>
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<pre class="code">
driftfile /var/lib/ntp/ntp.drift

server 0.pool.ntp.org
server 1.pool.ntp.org
server 2.pool.ntp.org
server 3.pool.ntp.org
server 0.pool.ntp.org
server 1.pool.ntp.org
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</pre>
8 changes: 8 additions & 0 deletions docs/ntppool/use/sample-pool-config.html
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<pre class="code">
driftfile /var/lib/ntp/ntp.drift

pool 2.pool.ntp.org iburst
pool 3.pool.ntp.org iburst
pool 0.pool.ntp.org iburst
pool 1.pool.ntp.org iburst
</pre>
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There needs to be only one pool directive. With chronyd 4 specified pools would result in 16 used servers. With ntpd, at least with some versions, I think it would decrease the number of servers as there is a dummy source added for each pool and I suspect it would increase the DNS traffic unnecessarily.

For ntpd, there should be tos maxclock 5 setting to limit the number of used servers to 4.

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I agree. And pool pool.ntp.org iburst would be a great choice, if it weren't for the fact that it has no AAAA-record. Hence, I propose pool 2.pool.ntp.org iburst.

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You are right. Unless maxsources is used, chronyd will use 4 servers per pool. Smart. 🕶️

Setting tos maxclock 5 is correct if declaring a single pool. According to the documentation of ntpsec (a fork of ntpd) using only a single pool declaration has some limitations. That limitation being that associations are slower to be established, I infer from the comments in the sample configuration.

I haven't used ntpd recently, but in chronyd having a single pool declared, gets you in sync within a minute.

I'm fine with changing the configuration snippet for ntpd to:

pool 2.pool.ntp.org iburst
tos maxclock 5

I left out the driftfile directive. It's distribution specific and I believe taken care of by most distribution's default configuration.

For chronyd we need a remark then, that tos maxclock is not needed.

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There needs to be only one pool directive. With chronyd 4 specified pools would result in 16 used servers.

@mlichvar is the number 4 determined by chrony or is it based on the number of addresses returned from a single DNS query of pool.ntp.org? If it's chrony, is that hardcoded or a configurable default value?

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It's configurable using maxsources in connection with pool. Default value is 4 and max value is 16.

4 changes: 4 additions & 0 deletions docs/ntppool/use/sample-timedatectl.html
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<pre class="code">
timedatectl set-timezone "Europe/Kiev"
timedatectl set-time "2012-10-30 18:17:16"
</pre>