sudo apt update sudo apt install chrony |
The config file is:
/etc/chrony/chrony.conf |
Basic things you might want to set:
NTP servers:
You can replace the default pool servers with your preferred NTP servers.
# Example: server time.google.com iburst server time.cloudflare.com iburst server 0.pool.ntp.org iburst server 1.pool.ntp.org iburst |
Allow clients to sync with your machine (if acting as a server):
# Allow clients from local network to query time allow 192.168.1.0/24 |
If you want your machine to serve as a clock without network access:
local stratum 10 |
Log settings:
Chrony can log stats:
log measurements statistics tracking logdir /var/log/chrony |
After editing /etc/chrony/chrony.conf:
sudo systemctl restart chrony |
Enable it to start on boot:
sudo systemctl enable chrony |
Chrony has a command-line tool:
chronyc |
Once in the interactive shell, you can run commands like:
tracking → Show how well the clock is synced (important).
sources → Show list of servers it is syncing with and their status.
sourcestats → Detailed stats for each server.
activity → See if Chrony is currently doing anything.
makestep → Force Chrony to immediately step the system clock.
exit → Quit the CLI.
Example:
chronyc tracking chronyc sources chronyc sourcestats |
You can also run chronyc commands directly:
chronyc tracking |
chronyc tracking Reference ID : 8.8.8.8 (time.google.com) Stratum : 2 Ref time (UTC) : Tue Apr 29 20:10:12 2025 System time : 0.000045678 seconds fast of NTP time Last offset : +0.000034567 seconds RMS offset : 0.000045678 seconds Frequency : 1.234 ppm fast |
sudo chronyc makestep |
This forces the system clock to immediately jump to the correct time instead of slewing it gradually (normally, NTP likes to gradually adjust).
Chrony (and NTP in general) uses UDP port 123.
Example with firewalld:
sudo firewall-cmd --add-service=ntp --permanent sudo firewall-cmd --reload |
Check if chrony is running:
sudo systemctl status chrony |
Check logs:
journalctl -u chrony |
If time isn't syncing, sources will show why.