How to configure ntp on debian 12.11?

To ensure accurate system time on your Debian 12 server, configuring NTP (Network Time Protocol) is essential. Debian 12 ships with systemd-timesyncd enabled by default, but for more advanced use cases or better control, switching to chrony or ntpd is recommended.

Step 1: Disable systemd-timesyncd (optional)

If you plan to use chrony or ntpd, it’s better to disable the default time service to avoid conflicts:

sudo systemctl stop systemd-timesyncd
sudo systemctl disable systemd-timesyncd

Step 2: Install the Chrony package

Chrony is the modern replacement for traditional ntpd, and it’s lightweight, fast, and accurate.

sudo apt update
sudo apt install chrony -y

Once installed, check the service status:

sudo systemctl status chrony

It should be active and running.

Step 3: Configure Chrony

Edit the configuration file:

sudo nano /etc/chrony/chrony.conf

Find the default pool entries and replace them with your preferred NTP servers. For example, you can use Debian’s NTP pool:

pool 0.debian.pool.ntp.org iburst
pool 1.debian.pool.ntp.org iburst
pool 2.debian.pool.ntp.org iburst
pool 3.debian.pool.ntp.org iburst

If your server is behind NAT or firewall, ensure that UDP port 123 is open.

sudo chronyc -a makestep

To force Chrony to sync immediately:

chronyc tracking

Optional: Add Local NTP Sources

To use a local NTP server (e.g., for internal time sync in a private network), add a line like this to chrony.conf:

server 192.168.1.1 iburst

Then restart the service:

sudo systemctl restart chrony

Step 4: Verify NTP Time Sync

Check which NTP server your system is using:

chronyc sources -v

You should see a list of peers and their synchronization status. An asterisk (*) next to a server indicates the currently selected time source.

To double-check system time and sync status:

timedatectl status

Look for System clock synchronized: yes and NTP service: active.

Alternative: Use ntpd instead of Chrony

If you prefer to use ntpd:

sudo apt install ntp -y

Edit the configuration file:

sudo nano /etc/ntp.conf

server 0.debian.pool.ntp.org iburst
server 1.debian.pool.ntp.org iburst

sudo systemctl restart ntp

ntpq -p