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Configure time synchronization with an external NTP server

Setting up NTP time synchronization is required when you prepare your ISO image to work with a cloud platform.

In the ready-made cloud server images, all the necessary settings for NTP synchronization are made.

Linux
Windows

Check the installed utility.
Customize the utility.

1. Check the installed utility

Connect to the server via SSH.
Check which utility is being used on the server:
```
systemctl status ntp
systemctl status chronyd
systemctl status systemd-timesyncd
```
We recommend using Chrony, but you can customize whichever utility is already installed on the server.
If you want to switch to Chrony, disable and uninstall the systemd-timesyncd and ntpd utilities and install Chrony:
```
systemctl disable <name>
sudo apt remove <name>
sudo apt-get install chronyd
```
Specify <name> as the name of the utility to be removed (ntp or systemd-timesyncd).

2. Customize the utility

Chrony
ntpd
systemd-timesyncd

Launch Chrony:
```
systemctl start chronyd
```
Open the Chrony configuration file in the vi text editor:
```
vi /etc/chrony/chrony.conf
```
Add or replace the NTP servers in the file. We recommend replacing the servers in the file with Selectel NTP servers, but you can specify any available NTP servers.
```
server <ntp_server> iburst
```
Specify <ntp_server> — the domain name or IP address of the NTP server.

If you need to specify multiple servers, specify each on a separate line, for example:
```
server 0.spb.ntp.selectel.ru iburst
server 1.spb.ntp.selectel.ru iburst
```
Exit the vi text editor with your changes saved:
```
:wq
```
Restart the Chrony utility:
```
sudo systemctl restart chronyd
```
Check the list of NTP servers in use:
```
chronyc -N sources
```

Open the ntpd configuration file in a text editorvi:
```
vi /etc/ntp.conf
```
Add or replace the NTP servers in the file. We recommend replacing the servers in the file with Selectel NTP servers, but you can specify any available NTP servers.
```
server <ntp_server> iburst
```
Specify <ntp_server> — the domain name or IP address of the NTP server.

If you need to specify multiple servers, specify each on a separate line, for example:
```
server 0.spb.ntp.selectel.ru iburst
server 1.spb.ntp.selectel.ru iburst
```
Exit the vi text editor with your changes saved:
```
:wq
```
Restart the ntpd utility:
```
sudo systemctl restart ntpd
```
Check the list of NTP servers in use:
```
ntpq -p
```

Open the ntpd configuration file in a vi text editor:
```
vi /etc/systemd/timesyncd.conf
```
In the NTP parameter, add or replace NTP servers. We recommend replacing the servers with Selectel NTP servers, but you can specify any available NTP servers.
```
NTP=<ntp_server>
```
Specify <ntp_server> — the domain name or IP address of the NTP server.

If you need to specify multiple NTP servers, enter them separated by a space, for example:
```
NTP=0.spb.ntp.selectel.ru 1.spb.ntp.selectel.ru
```
Exit the vi text editor with your changes saved:
```
:wq
```

Restart the systemd-timesyncd utility:

sudo systemctl restart systemd-timesyncd.service

Check that the utility is running and the time is synchronized:
```
timedatectl status
```
The response should show active in the NTP service field and yes in the System clock synchronized field .

Connect to the server using RDP.
Open the CLI.
Stop the Windows time service:
```
net stop w32time
```
Specify the NTP servers. We recommend replacing the servers with Selectel NTP servers, but you can specify any available NTP servers.
```
w32tm /config /syncfromflags:manual /manualpeerlist:"<ntp_server>" /update
```
Specify <ntp_server> — the domain name or IP address of the NTP server.

If you need to specify multiple NTP servers, enter them separated by a space, for example:
```
w32tm /config /syncfromflags:manual /manualpeerlist:"0.spb.ntp.selectel.ru 1.spb.ntp.selectel.ru" /update
```
Start the Windows Time Service:
```
net start w32time
```
Check the list of NTP servers in use:
```
w32tm /query /peers
```