Do I Really Need A NTP Server For Time Synchronisation?

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Time synchronisation is a critical aspect to modern computing, especially when computers are on a network or need to communicate with other networked machines.

Timestamps are crucial for computers to acknowledge when an event occurred and it is the only information they have to ascertain if an event has occurred. Without accurate time stamps the consequences can include:

• Loss of data
• Difficult to log errors
• Difficult to debug
• Failure to save
• Time sensitive applications may fail

Modern operating systems like Windows 7 have automatic synchronisation software already installed. W32Time has been a part of Microsoft’s different generations of operating systems for some time but in Windows 7 it is set to be automatically on (Rather than the user having to set it) – synchronising your PC straight out of the box.

With such NTP (Network Time Protocol) based synchronisation available by using internet time servers (normally Microsoft and NIST) many people may wonder if a dedicated time server is still required.

Problems with Internet Time Servers

There are several drawbacks to using this Internet time as a source of UTC (Coordinated Universal Time – the global timescale often referred to as GMT).

The first and most important drawback to internet time servers is their location through the firewall. Having to rely on a source of time across the internet means keeping the TCP port open – a crucial security weakness that can be used by malicious users or bots.

Another downside to internet time servers is their lack of guaranteed accuracy. While places like NIST (National Institute for Standards and Time) and Microsoft have reliable and accurate time servers – the accuracy can be dependent on how far away you are peering from. And many other time servers available as a source of internet time are less reliable – and as NTP can’t authenticate a time signal from across the internet – it can be difficult to assess.

Benefits of an External NTP Server

Dedicated external NTP servers are far more secure. They receive their tie from GPS satellites of Long Wave transmissions so the signals can’t be intercepted by computer hackers or malicious software. Also, NTP can authenticate the signals ensuring you know where they are coming from and how accurate they are.

With time being so important on modern networked computers, taking a risk with internet time may cost a lot more than any minor investment in a dedicated NTP time server.

Choosing a Source of Time for Computer Network Synchronization

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You don’t need me to tell you how important computer network time synchronization is. If you are reading this then you are probably well aware of the importance in ensuring all your computers, routers and devices on your network are running the same time.

Failure to synchronize a network can cause all sorts of problems, although with a lack of synchronicity the problems may go unnoticed as error finding and debugging a network can be nigh on impossible without a source of synchronized time.

There are multiple options for finding a source of accurate time too. Most time sources used for synchronisation are a source of UTC (Coordinated Universal Time) which is the international timescale.
However, there are pro’s and con’s to all sources:

Internet time

There are an almost an endless number of sources of UTC time on the internet. Some of these time sources are wholly inaccurate and unreliable but there are some trusted sources put out by people like NIST (National Institute for Standards and Time) and Microsoft.

However, regardless of how trusted the time source is, there are two problems with internet time sources. Firstly, an internet time server is actually a stratum 2 device. In other words, an internet time server is connected to another time server that gets its time from an atomic clock, usually from one of the sources below. So an internet source of time is never going to be as accurate or precise as using a stratum 1 time server yourself.

Secondly, and more importantly, internet sources of time operate through the firewall so a potential security breach is available to any malicious user who wishes to take advantage of the open ports.

GPS Time

GPS time is far more secure. Not only is a GPS time signal available anywhere with a line of sight view of the sky, but also GPS time signals can be received externally to the network. By using a GPS time server the GPS time signals can be received and by using NTP (Network Time Protocol) this time can be converted to UTC (GPS time is currently 17 seconds exactly behind GPS time) then distributed around the network.

MSF/WWVB Time

Radio broadcasts in long wave are transmitted by several national physics labs. NIST and the UK’s NPL are two such organisations and they transmit the UTC signals MSF (UK) and WWVB (USA) which can be received and utilised by a radio referenced NTP server.

When Time Servers go Bad

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“Time is what prevents everything from happening at once,’ said eminent physicist John Wheeler. And when it comes to computers his words couldn’t be any more relevant.

Timestamps are the only method that a computer has to establish if an event has occurred, is meant to occur or shouldn’t be occurring just yet. For a home PC, the computer relies on the inbuilt clock that displays the time on the corner of your operating system, and for most home uses this is satisfactory enough.

However for computer networks that have to communicate with each other, relying in individual system clocks can cause untold problems:

All clocks drift, and computer clocks are no different and problems occur when two machines are drifting at different rates as the time does not match up. This poses a conundrum for a computer as it is unsure of which time to believe and time critical events can fail to occur and even simple tasks like sending an email can cause time confusion on a network.

For these reasons, time servers are commonly used to receive the time from an external source and distribute it around the network. Most of these devices use the protocol NTP (Network Time Protocol) which is designed to provide a method of synchronising time on a network.

However, time servers are only as good as the time source that they rely on and when there is a problem with that source, synchronisation will fail and the problems mentioned above can occur.

The most common cause for time server failure or inaccuracy is the reliance on internet based sources of time. These can neither be authenticated by NTP nor guaranteed to be accurate and they can also lead to security issues with firewall intrusion and other malicious attacks.

Ensuring the NTP time server continues to get a source of highly accurate time is fairly straight forward and is all a matter of choosing an accurate, reliable and secure time source.

In most parts of the world there are two methods that can provide a secure and reliable source of time:

  • GPS time signals
  • Radio referenced time signals

GPS signals are available anywhere on the planet and are based on GPS time which is generated by atomic clocks onboard the satellites.

Radio referenced signals like MSF and WWVB are broadcast on long wave from physics laboratories like NIST and NPL.

Choosing a Source of Time for an NTP Synchronization

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Accurate time is essential in the modern world of internet banking, online auctions and global finance. Any computer network that is involved in global communication needs to have an accurate source of the global timescale UTC (Coordinated Universal Time) to be able to talk to other networks.

Receiving UTC is simple enough. It is available from multiple sources but some are more reliable than others:

Internet Time Sources

The internet is awash with time sources. These vary in reliability and accuracy but some trusted organisations like NIST (National Institute of Standards and Time) and Microsoft. However, there are disadvantages with internet time sources:

Reliability – The demand for internet sources of UTC often means it can be difficult to access them

Accuracy – most internet time servers are stratum 2 devices which means they rely on a source of time themselves. Often errors can occur and many sources of time can be very inaccurate.

Security – Perhaps the biggest issue with internet time sources is the risk they pose to security. To receive a time stamp from across the internet the firewall needs to have an opening to allow the signals to pass through; this can lead to malicious users taking advantage.

Radio Referenced Time Servers.

A secure method of receiving UTC time stamps is available by using a NTP time server that can receive radio signals from labs like NIST and NPL (National Physical Laboratory. Many countries have these broadcasted time signals which are highly accurate, reliable and secure.

GPS Time servers

Another source for dedicated time servers is GPS. The big advantage of a GPS NTP time server is that the time source is available everywhere on the planet with a clear view of the sky. GPS time servers are also highly accurate, reliable and just as secure as radio referenced time servers.

Common Internet Time Synchronisation Issues

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Keeping the clock on a PC system synchronised is important for many systems, networks and users that need time accuracy for applications and transactions. Nearly everything on a modern computer system is time reliant so when synchronisation fails all sorts of issues can arise from data getting lost and debugging becoming near impossible.

There are several methods of synchronising a computer system’s clock but the majority of them rely on the time synchronisation protocol NTP (Network Time Protocol).

By far the most common method is to make use of the myriad of online NTP time servers that relay the UTC time (Coordinated Universal Time). However, there are many common issues in using internet based time servers – here are some of them:

Can’t access the Internet time server

A common occurrence with Internet time sources is the inability to access them. This can be caused by several reasons:

• Too much traffic trying to access the server
• Website is down
• Your connection is down

The time from the time server is innacuurate

Most online sources of time are what are known as stratum 2 time servers. This means they get their time from another time server (stratum 1) that it connected to an atomic clock (stratum 0). If there is an error with the stratum 1 device the stratum 2 device will be wrong (and every device that is trying to get the time from it).

The time server is leading to security problems with the firewall

Another common problem caused by the fact that all online time servers need access through your firewall. Unfortunately this gives the opportunity for malicious users to make use of this back door into your system.

Eliminating Time Server Issues

Internet time sources are neither guaranteed to be accurate, reliable or secure so for any serious time synchronisation requirements an external source of time should be used. NTP time servers that plug into a network and receive the time from GPS or radio sources are a much more secure and reliable alternative. These NTP servers are also highly secure as they do not operate across the Internet.

The Worlds Atomic Clock Timekeepers

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When you set your watch to perhaps the speaking clock or the time on the internet, have you ever wondered who it is that sets those clocks and checks that they are accurate?

There is no single master clock used for the world’s timing but there are a constellation of clocks that are used as a basis for a universal timing system known as UTC (Coordinated Universal Time).

UTC enables all the world’s computer networks and other technology to talk to each other in perfect synchronicity which is vital in the modern world of internet trading and global communication.

But as mentioned controlling UTC is not down to one master clock, instead, a serious of highly precise atomic clocks based in different countries all work together to produce a timing source that is based on the time told by them all.

These UTC timekeepers include such notable organisations as the USA’s National Institute of Standards and Time (NIST) and the UK’s National Physical Laboratory (NPL) amongst others.

These organisations don’t just help ensure UTC is as accurate as possible but they also provide a source of UTC time available to the world’s computer networks and technologies.

To receive the time from these organisations, a NTP time server (Network Time Server) is required. These devices receive the broadcasts from places like NIST and NPL via long wave radio transmissions. The NTP server then distributes the timing signal across a network, adjusting individual system clocks to ensure that they are as accurate to UTC as possible.

A single dedicated NTP server can synchronize a computer network of hundreds and even thousands of machines and the accuracy of a network relying in UTC time from the broadcasts by NIST and NPL will also be highly precise.

The NIST timing signal is known as WWVB and is broadcast from Boulder Colorado in the heart of the USA whilst the UK’s NPL signal is broadcast in Cumbria in the North of England and is known as MSF – other countries have similar systems including the DSF signal broadcast out of Frankfurt, Germany.

GPS as a Timing Reference for NTP servers

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The GPS system is familiar to most people. Many cars now have a GPS satellite navigation device in their cars but there is more to the Global Positioning System than just wayfinding.

The Global Positioning System is a constellation of over thirty satellites all spinning around the globe. The GPS satellite network has been designed so that at any point in time there is at least four satellites overhead – no matter where you are on the globe.

Onboard each GPS satellite there is a highly precise atomic clock and it is the information from this clock that is sent through the GPS transmissions which by triangulation (using the signal from multiple satellites) a satellite navigation receiver can work out your position.

But these ultra precise timing signals have another use, unbeknown to many users of GPS systems. Because the timing signals from the GPS atomic clocks are so precise, they make a good source of time for synchronising all sorts of technologies – from computer networks to traffic cameras.

To utilise the GPS timing signals, a GPS time server is often used. These devices use NTP (Network Time Protocol) to distribute the GPS timing source to all devices on the NTP network.

NTP regularly checks the time on all the systems on its network and adjusts it accordingly if it has drifted to what the original GPS timing source is.

As GPS is available anywhere on the planet it provides a really handy source of time for many technologies and applications ensuring that whatever is synchronised to the GPS timing source will remain as accurate as possible.

A single GPS NTP server can synchronize hundreds and thousands of devices including routers, PCs and other hardware ensuring the entire network is running perfectly coordinated time.

Technologies that rely on Atomic Clocks (Part 2)

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GPS is not the only technology that is dependent on atomic clocks. The high levels of accuracy that are supplied by atomic clocks are used in other crucial technologies that we take for granted everyday.

Air traffic Control Not only are all aeroplanes and airliners now equipped with GPS to enable pilots and ground staff to know their exact location but atomic clocks are also used by air traffic controllers who need precise and accurate measurements and time between planes.

Traffic Lights and Road Congestion Systems – Traffic lights are another system that relies on atomic clock timing. Accuracy and synchronization is vital for traffic light systems as small errors in synchronization could lead to fatal accidents.

Congestion cameras and other systems such as parking metres also use atomic clocks as a basis of their timekeeping as this prevents any legal issues when issuing penalty notices.

CCTV – Closed circuit television is another large scale user of atomic clocks. CCTV cameras are often used in the fight against crime but as evidence they are ineffective in a court of law unless the timing information on the CCTV camera can be proved to be accurate. Failure to do so could lead to criminals escaping prosecution because despite the identification by the camera, proof that it was at the time and date of the offence can’t be clarified without accuracy and synchronization.

Internet – Many of the applications we now entrust to the internet are only made possible thanks to atomic clocks. Online trading, internet banking and even online auction houses all need accurate and synchronized time.

Imagine taking your savings from your bank account only finding that you can withdraw them again because another computer has a slower clock or imagine bidding on an internet auction site only to have your bid rejected by a bid that came before yours because it was made on a computer with a slower clock.

Using atomic clocks as a source for time is relatively straight forward for many technologies. Radio signals and even the GPS transmissions can be used as a source of atomic clock time and for computer systems, the protocol NTP (Network Time Protocol) will ensure any sized network will be synchronized perfectly together. Dedicated NTP time servers are used throughout the world in technologies and applications that require precise time.

Network Time Protocol and Computer Time Synchronization

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Ask any network administrator or IT engineer and ask them how important network time synchronization is and you’ll normally get the same answer – very.

Time is used in almost all aspects of computing for logging when events have happened. In fact timestamps are the only reference a computer can use to keep tracks of tasks it has done and those that it has yet to do.

When networks are unsynchronized the result can be a real headache for anybody tasked with debugging them. Data can be often lost, applications fail to commence, error logging is next to impossible, not to mention the security vulnerabilities that can result if there is no synchronized network time.

NTP (Network Time Protocol) is the leading time synchronisation application having been around since the 1980’s. It has been constantly developed and is used by virtually every computer network that requires accurate time.

Most operating systems have a version of NTP already installed and using it to synchronise a single computer is relatively straight forward by using the options in the clock settings or task bar.

However, by using the inbuilt NTP application or daemon on a computer will result in the device using a source of internet time as a timing reference. This is all well and good for single desk top machines but on a network a more secure solution is required.

It is vital on any computer network that there are no vulnerabilities in the firewall which can lead to attacks from malicious users. Keeping a port open to communicate with an internet timing source is one method an attacker can use to enter a network.

Fortunately there are alternatives to using the internet as a timing source. Atomic clock time signals can be received using long wave radio or GPS transmissions.

Dedicated NTP time server devices are available that make the process of time synchronisation extremely easy as the NTP servers receives the time (externally to the firewall) and can then distribute to all machines on a network – this is done securely and accurately with most networks synchronised to an NTP server working to within a few milliseconds of each other.

Atomic Clocks Now Doubled in Precision

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As with the advance of computer technology that seems to exponentially increase in capability every year, atomic clocks too seem to increase dramatically in their accuracy year on year.

Now, those pioneers of atomic clock technology, the US National Institute of Standards Time (NIST), have announced they have managed to produce an atomic clock with accuracy twice that of any clocks that have gone before.

The clock is based in a single aluminium atom and NIST claim it can remain accurate without losing a second in over 3.7 billion years (about the same length of time that life has existed Earth).

The previous most accurate clock was devised by the German Physikalisch-Technische Bundesanstalt (PTB) and was an optical clock based on a strontium atom and was accurate to a second in over a billion years. This new atomic clock by NIST is also an optical clock but is based on aluminium atoms, which according to NIST’s research with this clock, is far more accurate.

Optical clocks use lasers to hold atoms still and differ to the traditional atomic clocks used by computer networks using NTP servers (Network Time Protocol) and other technologies which are based on fountain clocks. Not only do these traditional fountain clocks use Caesium as their time keeping atom but instead of lasers they use super-cooled liquids and vacuums to control the atoms.

Thanks to work by NIST, PTB and the UK’s NPL (National Physical Laboratory) atomic clocks continue to advance exponentially, however, these new optical atomic clocks based on atoms like aluminium, mercury and strontium are a long way from being used as a basis for UTC (Coordinated Universal Time).

UTC is governed by a constellation of caesium fountain clocks that while still accurate to a second in 100,000 years are by far less precise than these optical clocks and are based on technology over fifty years old. And unfortunately until the world’s science community can agree on an atom and clock design to be used internationally, these precise atomic clocks will remain a play thing of the scientific community only.