====== NTP Client/Server (chrony) Configuration ======

AstLinux now supports the [[https://chrony.tuxfamily.org|chrony]] package, a versatile implementation of the Network Time Protocol [[wp>Network_Time_Protocol|NTP]].
It can synchronize the system clock with NTP servers, and can also operate as an NTPv4 (RFC 5905) server and peer to provide a time service to other computers in the network.

!!Note: AstLinux 1.2.9 or later is required for 'chrony' specific features!!
===== NTP Client Configuration =====

Select the Network Tab in the web interface.\\
{{:userdoc:ipv6-tunnel-network-tab.jpg?nolink|Network Tab}}

Locate the "NTP Server" entry within **Network Time Settings:**

Enter user defined NTP Servers (space separated) or select a regional "pool" server, “Save Settings”, then "Restart NTP Time" to apply.

!!Tip ->!! Any changes to the "Timezone" selection within this entry requires a System Reboot to apply.

===== NTP Server Configuration =====

Nothing additional to configure, any local LAN interface device can use the LAN gateway address as an NTP server (UDP 123).

!!Tip ->!! By default, the DHCP "ntp-server" options field provides the NTP server for each DHCP configured network segment.

===== Custom Configuration =====

By default a ''/etc/chrony.conf'' file is automatically generated from web interface settings.  For most users this is sufficient, and recommended, providing automatic ''/etc/chrony.conf'' configuration tweaks over time.

For advanced users who want addition control of the ''/etc/chrony.conf'' configuration, they can create a persistent ''/mnt/kd/chrony.conf'' file that will be automatically sym-linked to ''/etc/chrony.conf''.

Using the CLI, here is a brief how-to on generating a custom configuration for chrony.

Create a persistent ''/mnt/kd/chrony.conf'' file from the current automatically generated version:

  cp /etc/chrony.conf /mnt/kd/chrony.conf

Now edit ''/mnt/kd/chrony.conf'' to your liking, probably delete the "Autogenerated" first line so it won't confuse you later.

Now restart the NTP daemon with the new ''/mnt/kd/chrony.conf'' file:

  service ntpd stop
  service ntpd init

!!Tip ->!! The web interface Network and Edit tab will support editing the ''/mnt/kd/chrony.conf'' file if it exists.

If you want to specify a persistent driftfile, the destination directory must have ''ntp:ntp'' user/group privileges.  For example:

  mkdir /mnt/kd/ntp
  chown ntp:ntp /mnt/kd/ntp

Then in your custom ''/mnt/kd/chrony.conf'' file, edit the driftfile line to:

  driftfile /mnt/kd/ntp/chrony.drift

Then restart the NTP daemon (as above) to apply the change.

[[https://chrony.tuxfamily.org/documentation.html|Chrony Documentation]]
===== Statistics and Debugging Commands =====

The ''chronyc'' command connects to the ''chronyd'' daemon to retrieve useful information.  If ''chronyc'' is entered by itself you will enter an interactive mode with a ''chronyc>'' prompt //(supports tab-completion of commands)//.  Or just enter ''chronyc'' commands on the command line.

!!Note ->!! Some ''chronyc'' commands can actively change the ''chronyd'' operation, so carefully choose what commands you issue.  Below are some //safe// examples.

\\
Display information about current sources: (append -v for verbose)
  chronyc sources

Display statistics about collected measurements: (append -v for verbose)
  chronyc sourcestats

Display system time information:
  chronyc tracking

Report on clients that have accessed the server:
  chronyc clients

Display a list of commands:
  chronyc help

\\