Translated using DeepL

Machine-translated page for increased accessibility for English questioners.

Accurate time on the FI network

The server time.fi.muni.cz can be used to synchronize the exact time of the computers. The server provides the exact time using NTP (or SNTP) protocol from anywhere on the Internet and time protocol (RFC 868) inside the FI network.

This server is part of the NTP Pool Project' s distributed network of NTP servers, see also the monitoring graphs for IPv4 and for IPv6.

You can also read something about our practical experience with NTP operation in our blog article Precise Time and Network Transparency.

Time synchronization on Unix

For accurate synchronization, you need to have an NTP daemon running on your machine. In many distributions, a very simple one is part of the default installation: systemd-timesyncd. If you have one and want to use a faculty accurate time server, just set the NTP=time.fi.muni.cz line in the [Time] section of the /etc/systemd/timesyncd.conf configuration file and restart the daemon using systemctl restart systemd-timesyncd. Check the correctness of the settings via timedatectl timesync-status: you should see the name of the server you just set up on the first line.

You can also install a classic NTP daemon (typically a package ntp, not openntpd). In the /etc/ntp.conf or /etc/ntpsec/ntp.confconfiguration file, you can then set up the faculty NTP server by adding the line server time.fi.muni.cz iburstand commenting out the lines with the directives pool. You also need to edit the (possibly existing) configuration of tos: minclock must be 1 and minsane either not listed or also 1; for example, so tos minclock 1 minsane 1. Then restart the service: systemctl restart ntpd.

An alternative is chrony ( chronyd). If you did not set up the time.fi.muni.cz server when you installed it, this can be done by commenting out the pool directive line in the /etc/chrony.conf file and adding the server time.fi.muni.cz iburst line. Then restart the service: systemctl restart chronyd.

Time synchronization on Windows

On Windows, you can use the command

w32tm /config /manualpeerlist:time.fi.muni.cz /syncfromflags:manual /update

command, which must be run at a command prompt with administrator privileges. For the command to succeed, the Windows Time service must be running. It can be started from the command line using the command net start w32time, and can be set to start automatically at startup using the command sc config w32time start=auto.

To check the settings, use

w32tm /query /configuration

Possible problems

See https://support.microsoft.com/en-us/kb/2385818.