---
title: Network Time Security
description: Secure time synchronization with NTS protocol.
image: https://developers.cloudflare.com/core-services-preview.png
---

> Documentation Index  
> Fetch the complete documentation index at: https://developers.cloudflare.com/time-services/llms.txt  
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# Network Time Security

[Network Time Security ↗](https://datatracker.ietf.org/doc/html/rfc8915) (NTS) provides cryptographic security for the client-server mode of the Network Time Protocol (NTP). This allows users to obtain time in an authenticated manner.

## Background

The NTS protocol is divided into two phases:

1. **NTS Key Exchange**: Establishes the necessary key material between the NTP client and the server, using a [Transport Layer Security (TLS) handshake ↗](https://www.cloudflare.com/learning/ssl/what-happens-in-a-tls-handshake/) (the same public key infrastructure as the web). Once the keys are exchanged, the TLS channel is closed and the protocol enters the second phase.
2. **NTS Extension Fields for NTPv4**: Authenticates NTP time synchronization packets using previously established key material. For more information, refer to [RFC 8915 ↗](https://tools.ietf.org/html/rfc8915).

## Next steps

NTS is gaining support in many NTP implementations, including [Chrony ↗](https://chrony-project.org/documentation.html), [NTPsec ↗](https://www.ntpsec.org/), and [ntpd-rs ↗](https://github.com/pendulum-project/ntpd-rs). Read the relevant documentation for guidance on setting them up to point to our time service, `time.cloudflare.com`. Also see [Netnod's documentation ↗](https://www.netnod.se/netnod-time/how-to-use-nts) for configuring NTS clients.

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```