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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.
Modern systems usually have time synchronization secured automatically and also against multiple exact time servers, so it is typically not necessary to configure your machine as described here.
You can also read something about our practical experience with NTP operation in the article Precision Time and Network Transparency on our blog.
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