In this post, I describe how I configure a time server on an Ubuntu machine.
While the default configuration works for most users, I prefer to explicitly set up my upstream NTP servers.
Installing
The simplest way to install chrony is to download the package from the apt repository:
sudo apt install chrony
Configuring
The main chrony configuration file is located at:
/etc/chrony/chrony.conf
You can keep the default settings, but I usually replace the default pools with Google Public NTP servers.
Ubuntu 24.04 LTS and earlier
In older versions, the NTP servers were defined directly inside /etc/chrony/chrony.conf.
Default NTP pool servers:
pool ntp.ubuntu.com iburst maxsources 4
pool 0.ubuntu.pool.ntp.org iburst maxsources 1
pool 1.ubuntu.pool.ntp.org iburst maxsources 1
pool 2.ubuntu.pool.ntp.org iburst maxsources 2
I change them to the Google Public NTP servers:
server time1.google.com iburst
server time2.google.com iburst
server time3.google.com iburst
server time4.google.com iburst
Ubuntu 26.04 LTS and later
Starting with Ubuntu 26.04 LTS, NTP sources are managed via files in the /etc/chrony/sources.d/ directory.
To use custom NTP servers:
- Remove or disable the default source definitions (e.g., rename the extension part to disable it):
sudo rm /etc/chrony/sources.d/ubuntu-ntp-pools.sources - Create a new file for the Google sources:
sudo nano /etc/chrony/sources.d/google.sources - And add the NTP servers:
server time1.google.com iburst server time2.google.com iburst server time3.google.com iburst server time4.google.com iburst
Apply changes
After changing the settings, you need to restart the service:
sudo systemctl restart chrony
Changing timezone
You can change the system timezone using timedatectl:
sudo timedatectl set-timezone Etc/UTC
You can view all available timezones via:
timedatectl list-timezones
Checking chrony stats
To check the sources chrony is currently using:
chronyc sources
To check the tracking details (system offset, stratum, etc.):
chronyc tracking
Summary
sudo apt install chrony-
sudo nano /etc/chrony/chrony.conf- Or:
sudo nano /etc/chrony/sources.d/google.sources(for Ubuntu 26.04 LTS)
- Or:
- Change default NTP pool servers:
server time1.google.com iburst server time2.google.com iburst server time3.google.com iburst server time4.google.com iburst sudo systemctl restart chrony