Secure and och reliable network time

Access to accurate time is a prerequisite for modern society to function. We take it for granted that the clock in connected devices like computers or mobile phones is correct, but we may not often think about where that time comes from.

Today, the protocols NTP and NTS are commonly used for clock synchronization over routed computer networks such as the internet. NTS provides secure, authenticated, and encrypted data transmission, which makes so-called "man-in-the-middle" attacks more difficult—where someone can undetectedly send false data under a fake sender identity. This is a known vulnerability in NTP. Both protocols are open, and anyone can set up a server without any requirements on the quality of the time signal.

Varying Quality of NTP Servers

A survey conducted by RISE in 2024 showed that 75 percent of all publicly available NTP servers deviated less than 50 ms from UTC. These were distributed around a mean offset of 7 ms from UTC, with a standard deviation of 13 ms. The remaining 25 percent of NTP servers deviated significantly—up to several seconds—and showed no clear statistical distribution. There is therefore reason to carefully consider where you get your time from.

What Affects Accuracy?

The accuracy of time synchronization is affected by several factors. The network distance to the server matters, as the risk of asymmetric signal paths increases due to routing and interference. The quality of the server’s own time source can also vary. With a good connection to a high-quality time server, you can expect synchronization offsets from UTC in the range of just a few milliseconds.

Swedish Time Scale UTC(SP) via NTS or NTP

With RISE’s NTS servers, users can be assured that the time is delivered by RISE and directly linked to the official Swedish time scale UTC(SP). RISE also provides a classic NTP service with the same level of time accuracy.

We also offer services to monitor customers’ NTP/NTS servers in terms of availability and accuracy relative to UTC(SP). For customers who require even more precise time synchronization over networks, RISE can offer peer-to-peer solutions using, for example, Precision Time Protocol (PTP) or White Rabbit (WR).

Contact us to learn more!