Time synchronisation via Internet and NTP

P.T. Bridgeport Bear; from Pogo, Walt Kelly (http://www.eecis.udel.edu/%7emills/pictures.html)RISE offers services for synchronisation of computer clocks via Internet using the standard protocol for time distribution over the Internet, Network Time Protocol (NTP).

The typical client accuracy is in the order of 1 to 50 milliseconds  compared to UTC. The accuracy mainly depends on the network distance to the server but also on the capacity of the client's Internet connection.

The RISE NTP service is free of charge and is provided by four NTP-servers for both IPv4 and IPv6, two from RISE Borås :

  • ntp1.sptime.se    2001:6b0:42:1::123
  • ntp2.sptime.se  2001:6b0:42:2::123

and two from a RISE location in Stockholm:

  • ntp3.sptime.se  2001:6b0:42:3::123
  • ntp4.sptime.se  2001:6b0:42:4::123

For the time being even our traditional IPv4 only NTP servers in the sp.se domain are available. However, we do not recommend these servers in new client configurations.

  • ntp1.sp.se has changed IPv4-address to
  • ntp2.sp.se has changed IPv4-address to

We also offer an authenticated NTP-service that uses NTPv4 autokey (IFF identity scheme). Currently the service is under evaluation and is thus not considered official.
We appreciate comments via email (time@sp.se). 

  • ntp3.sp.se has changed IPv4-address to
    (the server answers authenticated NTP-packets only)

RISE is also co-operating with Netnod Internet Exchange in Sweden AB on the installation of NTP-servers in the Swedish Internet Exchange Points. You can read more about these servers at Netnod's webpage for timeservers.

Software to access the NTP servers is already installed in most versions of UNIX and Linux as well as MacOS and recent versions of Microsoft Windows. Software for other operating systems can be downloaded from the Internet. In addition to this RISE has written a simple Windows-based software. The software can be downloaded from the webpage software for time.

NTP time from the Swedish Netnod Internet Exchange servers is traceable back to the Swedish National time scale UTC(SP) by using GPS CV measurements between the servers and the RISE site in Borås, Sweden. You can read more about this at the webpage research within GPS.

PTS has decided that RISE should monitor Netnod's NTP servers. This includes a daily supervision and documentation of how well the servers distribute time. RISE has a webpage were you as a user can follow the accuracy of the servers.

Software for time

Perform your own on-site calibrations with our "Framtid" program.

GNSS - Global Navigation Satellite Systems

GNSS (Global Navigation Satellite Systems) is the common name of global satellite-based systems for navigation, positioning and time transfer.Read more...

Operating data and statistics for NTP Servers

SP has created a number of web pages that are automatically updated on a daily basis to give you the opportunity to follow the operation and the accuracy of the NTP-servers at SP. Read more...
RISE Research Institutes of Sweden, Phone 010-516 50 00, E-mail info@ri.se

The RISE institutes SP, Innventia and Swedish ICT have merged in order to become a stronger research and innovation partner for businesses and society.
During 2017 sp.se will be one of several websites within RISE. Please visit ri.se for more information about RISE.