Network Time Protocol

NTP is intended to synchronize all participating computers to within a few milliseconds of Coordinated Universal Time (UTC). It uses the intersection algorithm, a modified version of Marzullo's algorithm, to select accurate time servers and is designed to mitigate the effects of variable network latency. NTP can usually maintain time to within tens of milliseconds over the public Internet, and can achieve better than one millisecond accuracy in local area networks under ideal conditions. Asymmetric routes and network congestion can cause errors of 100 ms or more.

NTP in general

Installing a full-blown NTP server on the workstation at home is certainly an overkill. With client programs that query the time of a Stratum 2 server via SNTP (Simple NTP, RFC 5905) after start-up or at certain intervals, one can achieve sufficient accuracy. Such tools are available for all common operating systems. 

With all programmes, once a server has been selected, it may be switched off in the future or given a different name. You should therefore check the accessibility of the selected time sources from time to time and look for others if necessary. Likewise, the name and not the IP number of the server is always entered in the client configuration, because the number can change, but the name usually remains the same for years. 

If only the private surf PC or a DSL router is to query the time, it can be set to the NTP pool. Volunteers have entered the addresses of their NTP servers there, which they make available to the general public. Each time pool.ntp.org is accessed, the DNS server delivers a different address so that the load is distributed. A preceding digit delivers several different sources: 

  • 0.pool.ntp.org, 
  • 1.pool.ntp.org and 
  • 2.pool.ntp.org.

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NTP ntpdate ntpq ntpdc

Administration tools ntpdate, ntpq and ntpdc

With the tool ntpdate, it is possible to manually query individual time servers and, if necessary, derive a synchronisation. The tool ntpq, together with its sister tool ntpdc, represents the administration pool for the NTP daemon. In general, the tools ntpq and ntpdc can be called separately. They each offer their own shell to call their sub-commands.

NTP hierarchy stratum

NTP hierarchy

Each NTP server is classified in a stratum (layer, level, plural strata). This indicates how far away the server in an NTP network is from an external time source (atomic clock, GPS or time signal receiver): a stratum 1 server has an external source, a stratum 2 machine, on the other hand, has a stratum 1 server as a reference, and so on. The highest stratum is 16; a server of this level has not yet synchronised with other NTP servers. In practice, however, one gets by with four levels.

NTP logrotate

logrotate for NTP

What is important for using logrotate for NTP?

A few basic things to NTP

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What is the auto key procedure?

The general aim of the auto key security model is not to disguise the NTP data packets or their content. Rather, the procedure serves to verify the source of the data packets and to ensure that the packets have not been modified by third parties.  It uses public keys, session keys derived from them and X.509 certificates. Originally, the Autokey procedure was designed to be able to use public time servers as a reliable time source for NTP clients. Key features of the auto key security model are:

  • it is based on public key cryptography
  • it offers the possibility to assign the NTP servers to several security domains at the same time,
  • the algorithms have been specially adapted to reduce server-side resource requirements in large client installations,
  • the model can be used to automatically receive leap second tables and it requires a multicast environment.


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What is a false speaker (Byzantine error)?

The false speaker is a clock (NTP server) that not only delivers a wrong time, but also returns a different "wrong" time to each requesting system. In order to be robust against the error type "false speaker", synchronisation with at least 4 time servers per stratum level is required for the detection of a false speaker. With the calculation formula n=3t+1 it is possible to calculate the minimum number of time servers to be set up for each required false speaker detection rate.
The variables have the following meaning:

  • n="number of NTP instances required" and
  • t="Number of false speakers to be detected".

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What is a true chimer?

True chimers always deliver the qualitatively best time signal, taking into account packet runtimes, offset and drift calculations.  To detect the true chimer, at least 3 time service servers are required per stratum level.

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What is a false ticker?

A false ticker is a clock (NTP server) that consistently delivers a wrong time (e.g. shifted by 1h). In the case of only two NTP servers are available, it is not possible for a client to identify which server provides a wrong time. To be robust against this error, at least 3 time servers of the same level are needed.

In accordance with the legal requirements of data protection law (in particular the BDSG as amended and the European Data Protection Regulation 'DS-GVO'), we inform you below about the nature, scope and purpose of the processing of personal data by our company. This privacy policy also applies to our websites and social media profiles. With regard to the definition of terms such as "personal data" or "processing", we refer to Art. 4 DS-GVO.

Name and contact details of the person(s) responsible

Our responsible person(s) (hereinafter "responsible person") within the meaning of Art. 4 fig. 7 DS-GVO is:
Jens Mahnke
Karl-Kunger-Str. 56
12435 Berlin Germany
Email address: info@je-ru.de

Types of data, purposes of processing and categories of data subjects

Below we inform you about the type, scope and purpose of the collection, processing and use of personal data. 

1. types of data we process
Usage data (access times, websites visited, etc.), communication data (IP address, etc.),

2. purposes of the processing according to Art. 13 para. 1 c) DS-GVO
Technical and economic optimisation of the website, optimisation and statistical evaluation of our services, improving user experience, compilation of statistics,

3. categories of data subjects according to Art. 13 (1) (e) DS-GVO
Visitors/users of the website,

The data subjects are collectively referred to as "users".

Legal basis for the processing of personal data

Below we inform you about the legal basis for the processing of personal data. 1. if we have obtained your consent for the processing of personal data, Art. 6 para. 1 sentence 1 lit. a) DS-GVO is the legal basis. 2. if processing is necessary to comply with a contract or to carry out pre-contractual measures in response to your request, Art. 6 (1) sentence 1 lit. b) DS-GVO is the legal basis. If the processing is necessary to comply with a legal obligation to which we are subject (e.g. statutory retention obligations), Art. 6 (1) sentence 1 lit. c) DS-GVO is the legal basis. If the processing is necessary to protect the vital interests of the data subject or another natural person, the legal basis is Art. 6 (1) sentence 1 lit. d) DS-GVO. If the processing is necessary to protect our legitimate interests or the legitimate interests of a third party and your interests or fundamental rights and freedoms are not overridden in this respect, Art. 6 para. 1 sentence 1 lit. f) DS-GVO is the legal basis.

Disclosure of personal data to third parties and order processors

As a matter of principle, we do not pass on any data to third parties without your consent. However, if this should be the case, then the data will be passed on on the basis of the aforementioned legal grounds, e.g. when data is passed on to online payment providers for the fulfilment of a contract or due to a court order or because of a legal obligation to hand over the data for the purpose of criminal prosecution, to avert danger or to enforce intellectual property rights. We also use processors (external service providers e.g. for web hosting of our websites and databases) to process your data. If data is passed on to the processors as part of a contract processing agreement, this is always done in accordance with Art. 28 DS-GVO. In doing so, we select our processors carefully, monitor them regularly and have been granted a right to issue instructions regarding the data. In addition, the processors have to have taken suitable technical and organisational measures and comply with the data protection regulations according to the BDSG n.F. and the DS-GVO.

Data transfer to third countries

The adoption of the European General Data Protection Regulation (GDPR) has created a uniform basis for data protection in Europe. Your data is therefore predominantly processed by companies to which the GDPR applies. However, if processing is carried out by services of third parties outside the European Union or the European Economic Area, these have to fulfil the special requirements of Art. 44 ff. DS-GVO must be complied with. This means that the processing takes place on the basis of special guarantees, such as the officially recognised determination by the EU Commission of a level of data protection corresponding to the EU or the observance of officially recognised special contractual obligations, the so-called "standard contractual clauses". Insofar as we obtain your express consent to the transfer of data to the USA due to the invalidity of the so-called "Privacy Shield" in accordance with Article 49 (1) sentence 1 lit. a) DSGVO, we point out in this regard the risk of secret access by US authorities and the use of the data for monitoring purposes, possibly without any legal remedy for EU citizens.

Deletion of data and storage period

Unless expressly stated in this data protection declaration, your personal data will be erased or blocked as soon as you revoke the consent given for processing or the purpose for storing the data no longer applies or the data are no longer required for the purpose, unless their continued storage is necessary for evidence purposes or is contrary to statutory retention obligations. This includes, for example, retention obligations under commercial law for business letters in accordance with § 257 para. 1 of the German Commercial Code (HGB) (6 years) and retention obligations under tax law for receipts in accordance with § 147 para. 1 of the German Fiscal Code (AO) (10 years). When the prescribed retention period expires, your data will be blocked or deleted unless the storage is still necessary for the conclusion or fulfilment of a contract.

Existence of automated decision making

We do not use automated decision making or profiling.

Provision of our website and creation of log files

1. If you use our website for information purposes only (i.e. no registration and no other transmission of information), we only collect the personal data that your browser transmits to our server. If you wish to view our website, we collect the following data:

  • IP address;
  • Internet service provider of the user; 
  • Date and current time of the request;
  • browser type;
  • language and browser version;
  • Content of the retrieval;
  • Time zone;
  • Access status/HTTP status code;
  • Amount of data;
  • Websites from which the request came;
  • Operating system.

This data is not stored together with other personal data about you.

2. This data serves the purpose of user-friendly, functional and secure delivery of our website to you with functions and content as well as its optimisation and statistical evaluation.

3. The legal basis for this is our legitimate interest in data processing in accordance with Art. 6 (1) sentence 1 lit. f) DS-GVO, which also lies in the above purposes.

4. For security reasons, we store this data in server log files for a storage period of 70 days. After this period, they are automatically erased, unless we need to keep them for evidence purposes in the event of attacks on the server infrastructure or other legal violations.

Contacting us via contact form / email / fax / post

1. When contacting us via contact form, fax, mail or email form, your data will be processed for the purpose of handling the contact request.

2. If you have given your consent, the legal basis for processing your data is Art. 6 (1) sentence 1 lit. a) DS-GVO. The legal basis for the processing of data transmitted in the course of a contact request or email form, letter or fax is Art. 6 para. 1 p. 1 lit. f) DS-GVO. The responsible party has a legitimate interest in processing and storing the data in order to be able to answer users' enquiries, to preserve evidence for liability reasons and, if necessary, to be able to comply with its statutory retention obligations for business letters. If the objective of the contact is the conclusion of a contract, the additional legal basis for the processing is Article 6 (1) sentence 1 lit. b) DS-GVO.

3. We may store your details and contact request in our Customer Relationship Management System ("CRM System") or similar system.

4. The data is erased as soon as it is no longer required to achieve the purpose for which it was collected. For the personal data from the input mask of the contact form and those sent by email form, this is the case when the respective conversation with you has ended. The conversation is ended when it is clear from the circumstances that the matter in question has been conclusively clarified. We store enquiries from users who have an account or contract with us until two years after termination of the contract. In the case of legal archiving obligations, deletion takes place after their expiry: end of commercial law (6 years) and tax law (10 years) retention obligation.

5. You have the option to revoke your consent to the processing of personal data at any time in accordance with Art. 6 para. 1 p. 1 lit. a) DS-GVO. If you contact us by email form, you can object to the storage of personal data at any time.

Rights of the person concerned

1. Objection or revocation against the processing of your data

Insofar as the processing is based on your consent pursuant to Art. 6 para. 1 sentence 1 lit. a), Art. 7 DS-GVO, you have the right to revoke your consent at any time. This does not affect the lawfulness of the processing carried out on the basis of the consent until the revocation.

Insofar as we base the processing of your personal data on the balance of interests pursuant to Art. 6 (1) p. 1 lit. f) DS-GVO, you may object to the processing. This is the case if the processing is not necessary, in particular, for the compliance with a contract with you, which is shown by us in each case in the following description of the functions. When exercising such an objection, we ask you to explain the reasons why we should not process your personal data as we have done. In the event of your justified objection, we will review the merits of the case and either cease or adapt the data processing or show you our compelling legitimate grounds on the basis of which we will continue the processing.

You can object to the processing of your personal data for the purposes of advertising and data analysis at any time. You can exercise the right to object free of charge. You can inform us of your advertising objection using the following contact details: Jens Mahnke
Karl-Kunger-Str. 56 12435 Berlin Germany
Email address: info@je-ru.de

2. Right to information You have a right to information about your personal data stored by us in accordance with Art. 15 DS-GVO. This includes, in particular, information about the processing purposes, the category of personal data, the categories of recipients to whom your data has been or will be disclosed, the planned storage period, the origin of your data if it has not been collected directly from you.

3. Right to rectification You have the right to have inaccurate data corrected or correct data completed in accordance with Art. 16 DS-GVO.

4. Right to deletion You have the right to have your data stored by us deleted in accordance with Art. 17 DS-GVO, unless legal or contractual retention periods or other legal obligations or rights to further storage prevent this.

5. Right to restriction

You have the right to request a restriction in the processing of your personal data if one of the conditions in Art. 18 (1) a) to d) DS-GVO is complied with:

  • If you contest the accuracy of the personal data concerning you for a period of time which enables the controller to verify the accuracy of the personal data;
  • the processing is unlawful and you object to the erasure of the personal data and request instead the restriction of the use of the personal data;
  • the controller no longer needs the personal data for the purposes of the processing but you need them for the establishment, exercise or defence of legal claims; or
  • if you have lodged an objection to the processing pursuant to Art. 21 (1) DS-GVO and it is not yet clear whether the legitimate reasons of the controller outweigh your reasons.

6. Right to data portability You have a right to data portability in accordance with Art. 20 DS-GVO, which means that you can receive the personal data we hold about you in a structured, common and machine-readable format or request that it be transferred to another controller.

7. Right to complain You have the right to complain to a supervisory authority. As a rule, you can contact the supervisory authority for this purpose, in particular in the Member State of your place of residence, your workplace or the place of the alleged infringement.

Data security

In order to protect all personal data transmitted to us and to ensure that data protection regulations are complied with by us as well as by our external service providers, we have taken appropriate technical and organisational security measures. Therefore, among other things, all data is transmitted between your browser and our server via a secure SSL connection.

Status: 09/09/2022


Jens Mahnke 

Karl-Kunger-Strasse 56 

12435 Berlin 

Phone: 01717873970 

Email form: info@je-ru.de 

Disclaimer - legal information

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