How to use time.bjerkerud.com as your NTP server
time.bjerkerud.com — supports both plain NTP (UDP 123) and NTS (TCP 4460)
Open Settings → Time & Language → Date & Time, scroll down to Additional settings and click the Sync now text link (not the button itself). This opens a dialog where you can change the NTP server to time.bjerkerud.com.
w32tm /config /manualpeerlist:"time.bjerkerud.com" /syncfromflags:manual /reliable:YES /update net stop w32tm && net start w32tm w32tm /resync
Verify sync:
w32tm /stripchart /computer:time.bjerkerud.com /samples:5
Open System Settings → General → Date & Time, unlock the padlock, enable Set time and date automatically and enter time.bjerkerud.com as the server.
sudo systemsetup -setnetworktimeserver time.bjerkerud.com sudo systemsetup -setusingnetworktime on
Verify:
sntp time.bjerkerud.com
chrony is the recommended NTP client on modern Linux distributions.
sudo apt install chrony # Debian/Ubuntu sudo dnf install chrony # Fedora/RHEL
Add to /etc/chrony.conf:
server time.bjerkerud.com iburst
Requires chrony 4.0 or later:
server time.bjerkerud.com iburst nts
sudo systemctl restart chronyd chronyc sources chronyc authdata # shows NTS status
systemd-timesyncd is a lightweight NTP client built into systemd. It does not support NTS.
Edit /etc/systemd/timesyncd.conf:
[Time] NTP=time.bjerkerud.com
sudo systemctl restart systemd-timesyncd timedatectl show-timesync
Containers inherit the host system clock, so configure NTP on the host rather than inside containers. If you need per-container time sync, set the host NTP server as above and ensure the container has access to the host clock.
Mobile operating systems manage NTP automatically and do not allow custom NTP server configuration through normal settings. The device uses the carrier or platform default servers (Apple and Google respectively).
Network Time Security (NTS) is a cryptographic extension to NTP defined in RFC 8915. It authenticates time packets using TLS, preventing man-in-the-middle attacks and time spoofing.
NTS uses TCP port 4460 for the initial key exchange, then switches to the standard UDP port 123 for time packets. Both ports must be reachable from the client.
Use NTS wherever your client supports it. chrony 4.0+ on Linux supports NTS natively — just add nts to the server line.