Category: ntp server

Finding the Time

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Finding out what the time is, is something we all take for granted. Clocks are everywhere and a glance at a wristwatch, clock tower, computer screen or even a microwave will tell us what the time is. However, telling the time has not always been that easy.

Clocks didn’t arrive until the middle ages and their accuracy was incredibly poor. True time telling accuracy didn’t arrive until after the arrival of the electronic clock in the nineteenth century. However, many of the modern technologies and applications that we take for granted in the modern world such as satellite navigation, air traffic control and internet trading require a precision and accuracy that far exceeds an electronic clock.

Atomic clocks are by far the most accurate time telling devices. They are so accurate that the world’s global timescale that is based on them (Coordinated Universal Time) has to be occasionally adjusted to account for the slowing of the Earth’s rotation. These adjustments take the form of additional seconds known as leap seconds.

Atomic clock accuracy is so precise that not even a second of time is lost in over a million years whilst an electronic clock by comparison will lose a second in a week.

But is this accuracy really necessary? When you look at technologies such as global positioning then the answer is yes. Satellite navigation systems like GPS work by triangulating time signals generated by atomic clocks onboard the satellites. As these signals are transmitted at the speed of light they travel nearly 100,000 k m each second. Any inaccuracy in the clock by even a thousandth of a second could see the positioning information out by miles.

Computer networks that have to communicate with each other across the globe have to ensure they are running not just accurate time but also are synchronised with each other. Any transactions conducted on networks without synchronisation can result in all sorts of errors.

Fort his reason computer networks use NTP (Network Time Protocol) and network time servers often referred to as an NTP server. These devices receive a timing signal from an atomic clock and distribute it amongst a network in doing so a network is ensured to be as accurate and precise as possible.

Receiving the Time and Finding the Correct Time Source

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So you have decided to synchronize your network to UTC (Coordinated Universal Time), you have a time server that utilizes NTP (Network Time Protocol) now the only thing to decide on is where to receive the time from.

NTP servers do not generate time they simply receive a secure signal from an atomic clock but it is this constant checking of the time that keeps the NTP server accurate and in turn the network that it is synchronizing.

Receiving an atomic clock time signal is where the NTP server comes into its own. There are many sources of UTC time across the Internet but these are not recommended for any corporate use or for whenever security is an issue as internet sources of UTC are external to the firewall and can compromise security – we will discuss this in more detail in future posts.

Commonly, there are two types of time server. There are those that receive an atomic clock source of UTC time from long wave radio broadcasts or those that use the GPS network (Global Positioning System) as a source.

The long wave radio transmissions are broadcast by several national physics laboratories. The most common signals are the USA’s WWVB (broadcast by NIST – National Institute for Standards and Time), the UK’s MSF (broadcast by the UK National Physical Laboratory) and the German DCF signal (Broadcast by the German National Physics Laboratory).

Not every country produces these time signals and the signals are vulnerable to interference from topography. However, in the USA the WWVB signal is receivable in most areas of North America (including Canada) although the signal strength will vary depending on local geography such as mountains etc.

The GPS signal on the other hand is available literally everywhere on the planet as along as the GPS antenna attached to the GPS NTP server can have a clear view of the sky.

Both systems are a truly reliable and accurate method of UTC time and using either will allow synchronization of a computer network to within a few milliseconds of UTC.

Difficulties in telling the time!

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Precision in telling the time has never been as important as it is now. Ultra precise atomic clocks are the foundation for many of the technologies and innovations of the twentieth century. The internet, satellite navigation, air traffic control and global banking all just a few of the applications that is reliant on particularly accurate timekeeping.

The problem we have faced in the modern age is that our understanding exactly of what time is has changed tremendously over the last century. Previously it was thought that time was constant, unchanging and that we travelled forward in time at the same rate.

Measuring the passing of time was straight forward too. Each day, governed by the revolution of the Earth was divided into 24 equal amounts – the hour.  However, after the discoveries of Einstein during the last century, it was soon discovered time was not at all constant and could vary for different observers as speed and even gravity can slow it down.

As our timekeeping became more precise another problem became apparent and that was the age old method of keeping track of the time, by using the Earth’s rotation, was not an accurate method.

Because of the Moon’s gravitational influence on our oceans, the Earth’s spin is sporadic, sometimes falling short of the 24 hour day and sometimes running longer.

Atomic clocks were developed to try to keep time as precise as possible. They work by using the unchanging oscillations of an atom’s electron as they change orbit. This ‘ticking’ of an atom occurs over nine billion times a second in caesium atoms which makes them an ideal basis for a clock.

This ultra precise atomic clock time (known officially as International Atomic Time – TAI) is the basis for the world’s official timescale, although because of the need to keep the timescale in parallel with the rotation of the Earth (important when dealing with extra terrestrial bodies such as astronomical objects or even satellites) addition seconds, known as leap second, are added to TAI, this altered timescale is known as UTC – Coordinated Universal Time.

UTC is the timescale used by businesses, industry and governments all around the world. As it is governed by atomic clocks it means the entire world can communicate using the same timescale, governed by the ultra-precise atomic clocks. Computer networks all over the world receive this time using NTP servers (Network Time Protocol) ensuring that everybody has the same time to within a few milliseconds.

Synchronising Computer Networks to an Atomic Clock

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Atomic clocks are well-known for being accurate. Most people may never have seen one but are probably aware that atomic clocks keep highly precise time. In fact modern atomic clock will keep accurate time and not lose a second in one hundred million years.

This amount of precision may seem overkill but a multitude of modern technologies rely on atomic clocks and require such a high level of precision. A perfect example is the satellite navigation systems now found in most auto cars. GPS is reliant on atomic clocks because the satellite signals used in triangulation travel at the speed of light which in a single second can cover nearly 100,000 km.

So it can be seen how some modern technologies rely on this ultra precise timekeeping from atomic clocks but their use doesn’t stop there. Atomic clocks govern the world’s global timescale UTC (Coordinated Universal Time) and they can also be used to synchronise computer networks too.

It may seem extreme to use this nanosecond precision to synchronise computer networks too but as many time sensitive transactions are conducted across the internet with such trades as the stock exchange where prices can fall or rise each and every second it can be seen why atomic clocks are used.

To receive the time from an atomic clock a dedicated NTP server is the most secure and accurate method. These devices receive a time signal broadcast by either atomic clocks from national physics laboratories or direct from the atomic clocks onboard GPS satellites.

By using a dedicated NTP server a computer network will be more secure and as it is synchronised to UTC (the global timescale) it will in effect be synchronised with every other computer network using a NTP server.

The World in Synchronisation

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Time synchronisation plays an ever more important role in the modern world with more and more technologies reliant on accurate and reliable time.

Time synchronisation is not just important but can also be crucial in the safe running of systems such as air traffic control that simply couldn’t function without accurate synchronisation. Think of the catastrophes that could happen in the air of aircraft were out of synchronisation with each other?

In global commerce too accurate and reliable time synchronisation is highly important. When the world’s stock markets open in the morning and traders from across the world buy stock on their computers. As stock fluctuates second by second if machines are out of synchronisation it could cost millions.

But synchronisation is also imperative in modern computer networking; it keeps systems secure and enables proper control and debugging of systems. Even if a computer network is not involved in any time sensitive transactions a lack of synchronisation can leave it vulnerable to malicious attacks and can also be susceptible to data loss.

Accurate synchronisation is possible in computer networking thanks to two developments: UTC and NTP.

UTC is a timescale -coordinated universal time, it is based on GMT but is controlled by an array of atomic clocks making it accurate to within a few nanoseconds.

NTP is a software protocol – Network Time Protocol, designed to accurately synchronise computer networks to a single time source. Both of these implementations come together in a single device which is relied upon the world over to synchronise computer networks – the NTP server.

An NTP time server or network time server is a device that receives the time from an atomic clock, UTC source and distributes it across a network. Because the time source is continually checked by the time server and is from an atomic clock it makes the network accurate to within a few milliseconds of UTC providing synchronisation on a global scale.

The Clocks to Spring Forward at the Weekend

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It’s that time of year again when we lose an hour over the weekend as the clocks go forward to British Summer Time. Twice a year we alter the clocks but in an age of UTC (Coordinated Universal Time) and time server synchronisation is it really necessary?

The changing of the clocks is something that was discussed just before World War I when London builder William Willet suggested the idea as a way of improving the nation’s health (although his initial idea was to advance the clocks twenty minutes on each Sunday in April).

His idea wasn’t taken up although it sowed the seed of an idea and when the First World War erupted it was adopted by many nations as a way to economise and maximise daylight although many of these nations discarded the concept after the war, several including the UK and USA kept it.

Daylight saving has altered over the years but since 1972 it has remained as British Summer Time (BST) in the summer and Greenwich Meantime in the winter (GMT). However, despite is use for nearly a century the changing of the clocks remains controversial. For four years Britain experimented without daylight changing but it was proved unpopular in Scotland and the North where the mornings were darker.

This timescale hopping does cause confusion (I for one will miss that hour extra in bed on Sunday) but as the world of commerce adopts the global civil timescale (which fortunately is the same as GMT as UTC is adjusted with leap seconds to ensure GMT is unaffected by the slowing of the Earth’s rotation) is it still necessary?

The world of time synchronisation certainly doesn’t need to adjust for daylight saving. UTC is the same the world over and thanks to devices such as the NTP server can be synchronised so the entire world runs the same time.

NTP Synchronization and FAQ

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With a variety of acronyms and timescales the world of time synchronisation can be quite confusing here are some frequently asked questions we hope will help enlighten you.

What is NTP?

NTP is a protocol designed to synchronize computer networks across the internet or LAN (Local Area Networks). It is not the only time synchronization protocol available but it is the most widely used and the oldest having been conceived in the late 1980’s.

What are UTC and GMT?

UTC or Coordinated Universal Time is a global timescale, it is controlled by highly accurate atomic clocks but kept the same as GMT (Greenwich Meantime) by the use of leap seconds, added when the Earth’s rotation slows down. Strictly speaking GMT is the old civil timescale and based on when the sun is above the meridian line, however, as the two systems are identical in time thanks to leap seconds, UTC is often referred to as GMT and vice versa.

And a NTP Time Server?

These are devices that synchronize a computer network to UTC by receiving a time signal and distributing it with the protocol NTP which ensures all devices are running accurately to the timing reference.

Where to get UTC time from?

There are two secure methods of receiving UTC. The first is to utilize the long wave time signals broadcast by NIST (WWVB) NPL in the UK (MSF) and the German NPL (DCF) The other method is to use a the GPS network. GPS satellites broadcast an atomic clock signal that can be utilised and converted to UTC by the GPS NTP server.

The Hidden Cost of Free Time

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If you are reading this then you are probably aware of the importance time plays in IT systems and computer networks. Most computer administrators appreciate that precise time and accurate synchronisation are an important aspect of keeping a computer network error free and secure.

And yet, despite its importance many network administrators still rely on the Internet as a source of UTC time for their networks (UTC – Coordinated Universal Time), primarily because they see it as a quick and more importantly a free method of time synchronisation.

However, the drawbacks in using these free services may cost a lot more than the money saved on a dedicated NTP time server.

NTP (Network Time Protocol) is now present on nearly all computers and it is NTP that is used to synchronise computer systems. However, if an Internet time source is used then the source is outside the network firewall and this creates a serious vulnerability. Any external time source will require a port to be left open in the firewall to allow the time information packets through and this opening is too easy a way to exploit a network which can become victim to a DDOS attack (Distributed Denial of Service) or even allow malicious programmes through to take control of the machines themselves.

Another problem is the availability of stratum 1 time sources across the internet. Most online time sources come from stratum 2 time servers. These are devices that receive the time from a time server (stratum 1) that originally gets the information from an atomic clock (stratum 0).  While stratum 2 devices can be just as accurate as stratum 1 time servers, across the internet without NTP authentication the actual accuracy can not be guaranteed.

Furthermore, internet time sources have never been considered accurate or precise with surveys showing over half being inaccurate by over a second and the rest dependent on the distance from client as to whether they can provide any useful accuracy. Even organisations such as NIST publish  advisory notices on their time server pages about it unable to guarantee security or accuracy and yet millions of networks are still receiving time from across the internet.

With the decline in cost of dedicated radio referenced NTP time servers or GPS NTP server there has never been a better time to get one. And when you consider the cost of a computer breach or crashed network the NTP server will have paid for itself many times over.

Network Time Server Dual Signals

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A network time server (commonly referred to as the NTP time server after the protocol used in synchronisation – Network Time Protocol) is a device that receives a single time signal and distributes it to all devices on a network.

Network time servers are preferred as a synchronisation tool rather than the much simpler internet time servers because they are far more secure. Using the internet as a basis for time information would mean using a source outside the firewall which could allow malicious users to take advantage.

Network time servers on the other hand work inside the firewall by receiving source of UTC time (Coordinated Universal Time) from either the GPS network or specialist radio transmissions broadcast from national physics laboratories.

Both of these signals are incredibly accurate and secure with both methods providing millisecond accuracy to UTC. However, there are downsides to both systems. The radio signals broadcast by nation time and frequency laboratories are susceptible to interference and locality, while the GPS signal, although available literally everywhere on the globe can occasional be lost too (often due to bad weather interfering with the line-of-sight GPS signals.

For computer networks where high levels of accuracy are imperative, dual systems are often incorporated. These network time servers receive the time signal from both the GPS network and the radio transmissions and select an average for even more accuracy.  However, the real advantage of using a dual system is that if one signal fails, for what ever the reason, the network will not have to rely on the inaccurate system clocks as the other method of receiving UTC time should still be operational.

Does My Business Need Accurate Time Synchronisation Five question (part 1)

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Time synchronisation can be crucial for many computer networks. Correct synchronisation can protect a system from all sorts of security threats it will also ensure that the network is accurate and reliable but are dedicated NTP time server systems really necessary or can a network be run securely without a network time server?

Here are five questions to ask yourself to see if your network needs to be adequately synchronised.

1.  Does your network conduct time sensitive transactions across the internet?

If yes then accurate network time synchronisation is essential. Time is the only point of reference a computer has to identify two events so when it comes to a transaction across the internet such as sending an email, if it comes from an unsynchronised network, it may arrive before it was technically sent. This may lead to the email not being received as a computer cannot handle negative values when it comes to time.

2. Do you store valuable data?

Data loss is another ramification of not having a synchronised network. When a computer stores data it is stamped with the time. If that time is from an unsynchronised machine on a network then a computer may consider the data already saved or it may overwrite new data with older versions.

3. Is security important to your business and network?

Keeping a network secure is essential if you have any sensitive data on the machines. Malicious users have a myriad of ways of gaining access to computer networks and using the chaos caused by an unsynchronised network is one method they frequently take advantage of. Not having a synchronised network may mean it is impossible to identify if your network has been hacked into too as all records left on log files are time reliant too.