Network Time Security

Netnod’s Network Time Security (NTS) service is one of the first NTS-enabled time services in the world. This page gives a brief introduction to NTS, its benefits, and how to set it up on your devices.

What is NTS?

NTS is an essential development of the Network Time Protocol (NTP). It has been developed within the Internet Engineering Task Force (IETF) and adds a much needed layer of security to a protocol that is more than 30 years old and is vulnerable to certain types of attack. 

NTS consists of two protocols, a key exchange and extended NTP. This ensures that clients can validate that the time that they receive has been sent from the correct server. More detailed information about how NTS works is available here.

How to use NTS

NTS is a free service available to anyone, anywhere in the world. The only thing you need is an NTS-enabled NTP client. For more information about how to set this up, see here

Netnod’s NTS-enabled NTP service is freely available to anyone. You can point your NTS-enabled NTP client (using port 4460) to one of the following servers:

  • (for users anywhere in the world)
  • (for users close to Stockholm)
  • (for users close to Stockholm)

* Note that the NTS protocol is still a so-called Internet-draft within the IETF. Once It is ratified and becomes an RFC, the port number used could change.

Update Oct 6, 2020: The NTS draft has been accepted as RFC8915The official port number for NTS is now 4460.  Port 3443 and 4443 are still supported by Netnod’s NTS service as described above. For more info see here


What are the benefits of using NTS?

NTP is vulnerable to Man-in-the-Middle (MITM) attacks. This is where a malicious actor sits between you and the NTP server,  listens in on the conversation, forges messages and lies to you about time.

With many of today’s most important security processes dependent on accurate time, the consequences of receiving time from a malicious source are serious. Everything from establishing encrypted sessions and using DNSSEC to time-stamping financial transactions and preventing online fraud depends on accurate and secure time. By using NTS, you can be sure your devices are receiving accurate time from a reliable source.

More information 

Blog post: What is Network Time Security and why is it important?
Netnod’s press release announcing NTS service
How to set up an NTS-enabled NTP client 


Netnod has published a white paper on the new Network Time Security (NTS) standard. The white paper provides an important overview for network operators on the issues with the Network Time Protocol (NTP) that NTS has been designed to fix. It explains how NTS works and gives a detailed description of the authentication process that ensures networks receive time information from a trusted source.

Time and Frequency
17 Nov 2019
Netnod recently launched a Network Time Security (NTS) service. This page explains how you can start using NTS. It explains how to set up an NTS client and connect to Netnod’s NTS servers.
What is Network Time Security and why is it important?
Michael Cardell Widerkrantz, MC2019.09.30
A lot of the Internet’s most important security tools are dependent on accurate time. In this blogpost, MC Widerkrantz explains why the time you are getting might not be as secure as you think and how recent developments in Network Time Security can help.