Ubuntu Server ships with a built-in background daemon called systemd-timesyncd. This is a lightweight Network Time Protocol (NTP) client that continuously runs in the background, periodically reaching out to Ubuntu’s default NTP servers over the internet to ensure your server’s internal hardware clock remains perfectly synchronized to the millisecond.
While accurate timekeeping is critical for cryptographic certificates and log file sequencing, the default systemd-timesyncd client is too simplistic for enterprise deployments. It cannot act as an NTP server for other machines on your local network, and it lacks the advanced jitter and drift correction algorithms required by high-frequency trading platforms or distributed databases (like Cassandra or CockroachDB). If you need to deploy a robust, enterprise-grade time synchronization daemon like chrony or ntpd, having the default systemd client running simultaneously will cause catastrophic port conflicts on UDP port 123 and result in the two daemons fighting for control of the system clock. Before installing a professional NTP solution, you must completely disable systemd-timesyncd.
Disabling systemd-timesyncd via Systemctl
You must use the systemd control utility to gracefully stop the active daemon and permanently disable it from launching at boot.
- Open a Terminal session (or connect to your server via SSH).
- First, check the current status of the time synchronization daemon:
timedatectl status
(You will likely see “NTP service: active” in the output). - Instruct systemd to immediately halt the running process and permanently disable its startup trigger:
sudo systemctl disable --now systemd-timesyncd - (Optional but recommended): To absolutely guarantee that no other software dependency can accidentally wake the daemon back up in the future, you should mask the service. This symlinks the unit file to
/dev/null:sudo systemctl mask systemd-timesyncd
Verifying the Daemon is Dead
You can instantly verify that the lightweight client has been successfully eradicated.
- Run the time control status command again:
timedatectl status - Look at the output. The line should now definitively state:
NTP service: inactive
Your Ubuntu server’s clock is now entirely disconnected from the internet and relies strictly on the motherboard’s physical RTC (Real-Time Clock) battery. UDP Port 123 is now completely free and unallocated, allowing you to safely install and configure chrony or ntpd to take over the advanced timekeeping duties without any internal conflicts.