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- install and configure chrony
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Using Chrony
Install Chrony
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sudo apt update sudo apt install chrony |
Configure Chrony
The config file is:
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/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.
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# 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):
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# 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:
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local stratum 10 |
Log settings:
Chrony can log stats:
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log measurements statistics tracking logdir /var/log/chrony |
Restart Chrony
After editing /etc/chrony/chrony.conf:
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sudo systemctl restart chrony |
Enable it to start on boot:
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sudo systemctl enable chrony |
Interact with Chrony
Chrony has a command-line tool:
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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:
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chronyc tracking chronyc sources chronyc sourcestats |
You can also run chronyc commands directly:
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chronyc tracking |
Example: See Synchronization Status
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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 |
Force Immediate Sync (Useful for Fresh Setups)
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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).
Bonus: If you are firewalling, make sure UDP 123 is allowed
Chrony (and NTP in general) uses UDP port 123.
Example with firewalld:
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sudo firewall-cmd --add-service=ntp --permanent sudo firewall-cmd --reload |
Quick Troubleshooting:
Check if chrony is running:
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sudo systemctl status chrony |
Check logs:
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journalctl -u chrony |
If time isn't syncing, sources will show why.
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