Setting up time synchronization

At the department of computer science we have a timelab where specialized hardware and software work to offer the correct synchronized time to all systems.

The external facing main server is

ntp.cs.uu.nl

Which under normal circumstances operates as a stratum 1 ntp server, which can be used as a reference time source for any system on the Internet acting reasonably.

Setting up ntp under Unix

The best way to set up your system to use our server as a source of the correct time is to install ntpd which is usually available as a package. When asked to select a time server enter the name ntp.cs.uu.nl or edit the ntp.conf file to have one line server ntp.cs.uu.nl (and maybe remove other server lines).

Setting up ntp under Windows XP Professional & Windows 2000

Open a command prompt (Start, Run, 'cmd') and type the commands:

net time /setsntp:ntp.cs.uu.nl
net stop w32time
net start w32time

Note this microsoft kb article: Time synchronization may not succeed when you try to synchronize with a non-Windows NTP server in Windows Server 2003.

Setting up ntp under Windows XP home

Double-click on the time in the bottom right hand side of the screen, a "Date and time properties" window will open. Select the tab "Internet time" and check the box "Automatically synchronize with an Internet time server" and type the name ntp.cs.uu.nl in the box.

Multicast time

We multicast the time from 131.211.84.189 to the default multicast ntp group 224.0.1.1 (NTP.MCAST.NET). If you see traffic from 131.211.84.189 on this group (check first) and want to use this (within our ttl range) as a source and want to authenticate it, set up the following entry in the ntp keyfile /etc/ntp.keys

122 M ntpcsuu

And add the following to /etc/ntp.conf

keys /etc/ntp.keys
trustedkey  122
multicastclient 224.0.1.1

We consider multicast time service very experimental and may shut this down.

Abuse

Complaining about getting ntp answers to requests from your IP will get that IP added to the local filterlist. Only full apologies for annoying us and wasting our time will get you removed again. This is a public service on the Internet.

Related pages

NTP events log

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