Supporting the worldwide pool of NTP servers from pool.ntp.org with your own resources is really easy. Only a few steps from configuring the package to registering on the pool.ntp.org site need to be done
The network time protocol is being used in most networks to achieve nearly the same time on every system. Its not only nice to watch at the clocks in your network realizing that they all show the same time, nearly exact values are very important for authentication mechanisms like the authentication of computers in a Microsoft Active Directory and many more.
Normally you have one device in your network which syncs its time with one or more servers from the internet and then announces the current time to the other devices in the network. In a Microsoft Active Directory network for example this is done by the domain controller which hosts the FSMO role of the PDC-emulator.
A good choice for a NTP server as a source from the internet is a complete pool of NTP servers like pool.ntp.org. This pool contains a lot of servers which are announcing their time to the internet.
To also become a member of this pool you have to configure your /etc/ntp.conf in the following way (other configs are also possible, but this is the config I use for my server):
# /etc/ntp.conf, configuration for ntpd; see ntp.conf(5) for help
# Enable this if you want statistics to be logged.
statistics loopstats peerstats clockstats
filegen loopstats file loopstats type day enable
filegen peerstats file peerstats type day enable
filegen clockstats file clockstats type day enable
# Specify one or more NTP servers.
# Use servers from the NTP Pool Project. Approved by Ubuntu Technical Board
# on 2011-02-08 (LP: #104525). See http://www.pool.ntp.org/join.html for
# more information.
# Access control configuration; see /usr/share/doc/ntp-doc/html/accopt.html for
# details. The web page <http://support.ntp.org/bin/view/Support/AccessRestrictions>
# might also be helpful.
# Note that "restrict" applies to both servers and clients, so a configuration
# that might be intended to block requests from certain clients could also end
# up blocking replies from your own upstream servers.
# By default, exchange time with everybody, but don't allow configuration.
restrict -4 default kod notrap nomodify nopeer noquery limited
restrict -6 default kod notrap nomodify nopeer noquery limited
# Local users may interrogate the ntp server more closely.
# Needed for adding pool entries
restrict source notrap nomodify noquery
After editing the ntp.conf file you have to issue a
service ntp reload
Now its time to visit http://www.pool.ntp.org/en/join.html to request your server to be added.
You can find some configuration recommendations under http://www.pool.ntp.org/en/join/configuration.html (which are already used in my ntp.conf)
After you have created your account and requested your server to be added it will take several hours during which your server is being monitored for correct time values and reachability. Only if you achieve a score of at least 10.0 points your server will be added to the pool. If I remember correct it took about 3 or 4 days for my server to achieve the max. score of 20.0 (here are my statistics), not a big thing. The only thing you need is a static IP address and your server has to be up 24/7 (short downtime / reboots shouldn’t be the problem as every server needs its patches and reboots from time to time).