---
title: "Set up NTP synchronisation - IT Security"
slug: "it-security-hardening-set-up-ntp-synchronisation-en"
updated: 2026-04-07T06:19:49Z
published: 2026-04-07T06:19:49Z
canonical: "docs.insys-icom.com/it-security-hardening-set-up-ntp-synchronisation-en"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://docs.insys-icom.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Set up NTP synchronisation - IT Security

The NTP synchronisation provides for a regular update of the internal clock of the router.

The following elements are required to synchronise the internal clock with the NTP (Network Time Protocol= server:

- Specification of the NTP server and the timezone
- Event for triggering the synchronisation
- Firewall rule that permits the router to connect to NTP server

  1. Click in the ![cog](https://docs.insys-icom.de/assets/icons/cog.png) *Administration* → *Time / Date* menu in the *Clock synchronisation* section on ![pencil](https://docs.insys-icom.de/assets/icons/pencil.png) and select the *Time zone* of the router location.
  2. Take the suggested NTP server of the Physikalisch-Technische Bundesanstalt (**ptbtime1.ptb.de**) or enter the address of an alternative NTP server into the *Time server* field.
  3. Click on **SUBMIT** .
  4. Click in the ![update](https://docs.insys-icom.de/assets/icons/update.png) *Events* → *Events* menu on ![plus](https://docs.insys-icom.de/assets/icons/plus.png) and add a new event:
- *Event*: select a regular occurring event that is supposed to trigger the NTP synchronisation (such as the change of an interface status to online or the expiry of a timer)
- *Action*: **Synchronise clocck via NTP**

  1. Click on **SUBMIT** .
  2. Click in the ![lan](https://docs.insys-icom.de/assets/icons/lan.png) *Network* → *Firewall / NAT* menu in the *IP-Filter* section on ![plus](https://docs.insys-icom.de/assets/icons/plus.png) and add a new filter rule:
- *Packet direction*: **OUTPUT**
- *IP version*: **All**
- *Protocol*: **UDP**
- *Output interface*: select the configured WAN interface, e. g. **lte2**
- *Destination port*: 123

  1. Click on **SUBMIT** .
  2. Click on **ACTIVATE PROFILE** **![cog white](https://docs.insys-icom.de/assets/icons/cog_white.png)** .
  3. To test the NTP synchronisation, click in the ![cog](https://docs.insys-icom.de/assets/icons/cog.png) *Administration* → *Time / Date* menu in the *Clock synchronisation* section on ![refresh](https://docs.insys-icom.de/assets/icons/refresh.png).