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An access control system is an essential feature of any modern security system. Without accurate time stamps, however, access control logs cannot be reliably used for event reconstruction or other legal purposes. Therefore, it is essential to use a system that delivers accurate time stamping. Unfortunately, many systems rely on clocks that have the tendency to drift and gradually move away from the actual current time. By understanding how time stamping works and how to use it properly, organisations can more effectively protect themselves.

Let’s take a concrete example of an inaccurate time stamp in an access control system:

An employee sneaking into an area of a building. In the same area, IT equipment (a computer) was stolen and disconnected from the local network. Yet the company cannot demonstrate that the employee is responsible for the theft.


Because the history of the computer system shows that it was disconnected from the network before (e.g. server clock indicating 9:10 am) the employee entered the area using the access reader (local clock of the device indicating 9:50 am).

This company could have easily prevented this serious security problem by using a time server that distributes a reference time over its entire network infrastructure in order to synchronize both computer and access control reader.

Network time protocol

Network time protocol, or NTP, is a time synchronization distribution standard that works easily with IP-based systems, and software for NTP is readily available for just about any operating system. In fact, most IP access readers, computers and other devices already include pre-installed NTP client software. However, an NTP time server is needed for the network in order to synchronize the NTP client.

Local NTP Time Servers: Safe and Secure

To ensure network security when using NTP, it is highly recommended that you use a local dedicated NTP time server.

Free internet time servers are available, but they are vulnerable to cyberattacks and require an open port in your firewall. They make you a prime target for hackers looking to interfere with the time synchronization process by distributing false time and causing network outages. These actions are often a precursor to further malicious activities such as data theft.

A local NTP time server sits within your firewall, meaning that you don’t have to create a potential vulnerability in your network with an open port and reconfigure your firewall settings.

NTP time servers

A vast number of free public NTP servers are readily available via the internet. However, these sources of time are not traceable or guaranteed, and you must have an open port in your firewall to use such servers, which is a security threat.

They also require a continuous connection to the internet, which also poses a problem for closed security systems. For these applications, relying on a time source from outside the network is bad practice in general.

A private and dedicated NTP time server synchronizes itself to precise time from GNSS (Global Navigation Satellite System) satellites or radio signals such ALS, DCF or MSF. It operates securely behind a firewall to achieve the time synchronization of all elements of a system.

When setting up an access control system, make sure that it has the technological features that are necessary for producing accurate time stamps. With a dedicated NTP time server, an access control system delivers the time accuracy needed for organisations of all sizes and scopes.

Bodet provides access control and video solutions (link to Bodet). Our NTP server range is designed to be tailored to meet your access control requirements.


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