Category: advanced NTP

NTP Servers and the Different Time Sources

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NTP servers are essential devices for computer network time synchronisation. Ensuring a network coincides with UTC (Coordinated Universal Time) is vital in modern communications such as the Internet and is the primary function of the network time server (NTP server).

As their name suggests, these time servers use the protocol NTP (Network Time Protocol) to handle the synchronisation requests. NTP is already installed in many operating systems and synchronisation is possible without an NTP server by utilising an Internet time source, this can be unsecure and inaccurate for many network needs.

Network time servers receive a far more accurate and secure time signal. There are two methods of receiving the time using a time server: utilising the GPS network or receiving long wave radio transmissions.

Both these methods of receiving a time source are secure as they are external to any network firewall. They are also accurate as both sources of time are generated directly by atomic clocks rather than an Internet time service that are normally NTP devices connected to a third party atomic clock.

The GPS network provides an ideal source of time for NTP servers as the signals are available anywhere. The only downside of using the GPS network is that a view of the sky is required to lock-on to a satellite.

Radio referenced time sources are more flexible in that the long wave signal can be received indoors. They are limited in strength and not every country has a time signal although some signals such as the German DCF and the USA WVBB are available in neighbouring states.

Setting up Windows XP as an NTP Server

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A network time server or NTP server (Network Time Protocol), is a central computer or server on a network that controls the time and synchronises all machines on that network to it.

Windows XP can be set up to operate as an NTP server to synchronise the rest of the computers and devices on a network. Setting up a Windows XP machine to act as a NTP server involves editing the registry, however, editing an operating system registry can lead to potential problems and should only be conducted by somebody with experience of registry editing.

To configure Windows XP as an NTP server the first thing to do is to open the registry editor in Windows. This is done by clicking the Start button and selecting “Run” from the menu. Enter “regedit” in the run menu and press return. This should open the Windows registry editor.

Select the: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W32Time\TimeProviders\NtpServer\ folder in the left hand pane. This folder holds the values for the NTP server.

Right-click the “Enabled” key in the right window pane and select “Properties”. This should open a dialog box where you can alter the value of the registry key. Enter “1” in the window, setting the value to “True” which turns the XP computer into a time server.

Close the registry and open the DOS command prompt by clicking the Windows Start button, selecting “Run”. Then type “cmd” in the text box and press return.

Type “Net stop w32time” into the command prompt and press “Enter.” Now type “net start w32time” this will restart the time server for Windows XP.

However, the XP machine, which is now set as a NTP server, will merely distribute the time it currently holds. If this time is inaccurate then it will inaccurate time that is distributed amongst the network.

To ensure an accurate and secure source of time is used then a dedicated NTP time server that receives the time from an atomic clock source should be used.

Network Time Protocol Time Synchronisation Made Easy

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One of the most important aspects of networking is keeping all devices synchronised to the correct time. Incorrect network time and lack of synchronisation can play havoc with system processes and can lead to untold errors and problems debugging.

And failing to ensure devices are continually checked to prevent drift can also lead to a synchronised network slowly becoming unsynchronised and leading to the kinds of problems aforementioned.

However, ensuring a network not only has the correct time but that that time is not drifting is achieved using the time protocol NTP.

Network Time Protocol (NTP) is not the only time synchronisation protocol but it is by far the most widely used. It is an open source protocol but is continually updated by a large community of Internet time keepers.

NTP is based around an algorithm that can work out the correct and most accurate time from a range of sources. NTP allows a single time source to be used by a network of hundreds and thousands of machines and it can keep each one accurate to that time source to within a few milliseconds.

The easiest way of synchronising a network with NTP is to use a NTP time server, also known as a network time server.

NTP servers use an external source of time, either from the GPS network (Global Positioning System), or from broadcasts from national physics laboratories such as NIST in the US or NPL in the UK.

These time signals are generated by atomic clocks which are many times more accurate than the clocks on computers and servers. NTP will distribute this atomic clock time to all devices on a network it will then keep checking each device to ensure there is no drift and correcting the device if there is.

Time Synchronization on Windows 7

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Windows 7, the latest operating system from Microsoft is also their first operating system that automatically synchronizes the PC clock to an internet source of UTC time (Coordinated Universal Time). From the moment a Windows 7 computer is switched on and is connected to the Internet it will request time signals from the Microsoft time service – time.windows.com.

While for many home users this will save them the hassle of setting and correcting their clock as it drifts, for business users it may be problematic as internet time sources are not secure and receiving a time source through the UDP port on the firewall could lead to security breaches and as Internet time sources can’t be authenticated by NTP (Network Time Protocol) the signals can be hijacked by malicious users.

This internet time source can be deactivated by opening the clock and date dialogue box, and opening the Internet Time tab, clicking the ’Change’ setting button and unchecking the ‘Synchronize with an Internet time server< option.’

Whilst this will unsure no unwanted traffic will be coming through your firewall it will also mean that the Windows 7 machine will not be synchronised to UTC and its timekeeping will be reliant on the motherboard clock, which will eventually drift.

To synchronize a network of Windows 7 machines to an accurate and secure source of UTC then the most practical and simplest solution is to plug in a dedicated NTP time server. These connect directly to a router or switch and enable the safe receiving of an atomic clock time source.

NTP time servers use the highly accurate and secure GPS signal (Global Positioning System) available everywhere on the planet or more localized long wave radio signals transmitted by several national physics laboratories such as NIST and NPL.

Choosing a Time Source for UTC Synchronization

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Ensuring a computer network is time synchronized is vital in modern computer networks. Synchronization, not just between different machines on a network, but also each computer network that communicates with other networks needs to be synchronized with them too.

UTC (Coordinated Universal Time) is a global timescale that allows networks on other sides of the globe to be synchronized together. Synchronizing a network to UTC is relatively straightforward thanks to NTP (Network Time Protocol) the software protocol designed for this very purpose.

Most operating systems, including the latest Microsoft incarnation Windows 7, have a version of NTP (often in a simplified form known as SNTP), that allows a single time source to be used to synchronize every computer and device on a network.

Selecting a source for this time reference is the only real difficulty in synchronizing a network. There are three main locations where UTC time can accurately be received from:

Internet Time

There are many sources of internet time and the latest version of Windows (Windows 7) automatically synchronizes to Microsoft’s time server time.windows.com, so if Internet time is adequate Windows 7 users need not alter their settings. However, for computer networks where security is an issue then internet time sources can leave a system vulnerable as the time has to be received through the firewall forcing a UDP port to be left open. This can be utilised by malicious users. Furthermore, there is no authentication with an internet time source so the timecode could be hijacked before it arrives at your network.

GPS Time

Available literally everywhere on the globe, GPS provides a 24-hour, 365 days-a-year source of UTC time. Delivered externally to the firewall via the GPS satellite signal, time synchronization with GPS is accurate and secure.

Radio Transmissions

Usually broadcast by national physics laboratories such as NIST in the US and the UK’s NPL, the time signals are received via longwave and are also external to the firewall so are secure and accurate.

A dedicated NTP time server can receive both radio and GPS time signal guaranteeing accuracy and security.

Why we Synchronize the Time

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We live and work in a totally different world to the one that many of us were born into. We are now as likely to buy something from across the internet as stroll down the coal high street. And big business and commerce has changed too with the marketplace becoming truly global and the internet being the most common tool for trade.

Trading globally does provide its problems though as different timescales govern the different countries across the globe. To ensure parity a global timescale was introduced in the 1970’s knows Coordinated Universal Time (UTC). However, as e-commerce advanced so did the need to ensure accurate synchronization to UTC.

The biggest problem is that most clocks and watches, including those inbuilt into computer motherboards, are susceptible to drift. And as different machines will drift at different rates, global communication and e-commerce could be impossible. Just think of the difference a second can make in marketplaces like the stock exchange, where fortunes are won or lost, or when you purchase seat reservations online, what would happen if somebody on a computer with slower clock booked the same seat after you, the computer’s timestamps will show the person booked before you.

Other unforeseen errors can result, even in internal networks, when computers are running different times. Data can get lost, errors can be difficult to log, track down and fix and malicious users can take advantage of the time confusion.

To ensure truly global synchronization, computer networks can synchronize to an atomic clock allowing all computers on a network o remain within a few milliseconds of UTC. Compute networks use NTP servers (Network Time Protocol) to ensure accurate synchronization, most NTP servers receive the atomic clock time from either GPS satellites of radio frequencies.

How Computers Keep Abreast of Time

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Time governs our lives and keeping abreast of it is vital if we want to get to work on time, make it home for dinner or watch our favourite shows of an evening.

It is also crucial for computer systems. Computers use time as a point of reference, indeed, time is the only point of reference it can use to distinguish between two events and it is crucial that computers operating in networks are synchronized together.

Time synchronization is when all computers that are connected together run the same time. Time synchronization, however, is not simple to implement, primarily because computers are not good time keepers.

We are all used to the time being displayed on the bottom right hand of our computer desktops but this time is normally generated by the onboard crystal oscillator (normally quartz) on the motherboard.

Unfortunately these onboard clocks are prone to drift and a computer clock may lose or gain a second or so each day. While this may not sound like much, it can soon accumulate and with some networks consisting of hundreds and even thousands of machines, if they are all running different times its not hard to imagine the consequences; emails may arrive before they are sent, data may fails to backup, files will get lost and the networks will be amass of confusion and nearly impossible to debug.

To ensure synchronization throughout a network all devices must connect to a single time source. NTP (Network Time Protocol) has been devised for this very purpose and can distribute a time source to all devices and ensure that any drift is countered.

For true accuracy the single time source should be a source of UTC (Coordinated Universal Time) which is a global timescale that is used across continents and pays no heed to timezones, this allows networks on opposite sides of the Earth to be synchronized together.

A source of UTC should also be governed by an atomic clock as any drift in the time will mean that your network will be out of sync with UTC. By far the easiest, most efficient, secure, accurate and reliable method of receiving an atomic clock source of UTC is to use a dedicated NTP time server. NTP servers receive the UTC time from either the GPS network (Global Positioning System) or from radio transmission broadcast by national physics laboratories such as NIST or NPL.

Seven Reasons why your Network needs a Time Server

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Time servers, often referred to as NTP time servers after the protocol (Network Time Protocol) used to distribute time are an increasingly important part of any computer network. The NTP server receives a timing signal from an accurate source (such as an atomic clock) and then distributes it to all devices on the network.

However, despite the increasing importance of these time synchronisation devices, many network administrators still fail to accurately synchronise their networks and can leave their entire computer system vulnerable.

Here are seven reasons why a NTP time server is a crucial piece of equipment for YOUR network:

• Security: NTP servers use an external source of time and don’t rely on an open firewall port. An unsynchronized server will also be vulnerable to malicious users who can take advantage of time differences.

• Error logging: failing to adequately synchronize a computer network may mean that it is near impossible to trace errors or malicious attack, especially if the times on the log files from different machine do not match.

• Legal Protection: Not being able to prove the time can have legal implications if somebody has committed fraud or other illegal activity against your company.

• Accuracy: NTP Time Servers ensure that all networked computers are synchronized automatically to the exact time throughout your network so everybody in your company can have access to the exact time.

• Global Harmony: A global timescale known as UTC (Coordinated Universal Time) has been developed to ensure that systems across the globe can run the exact same time. By utilising a NTP server not only will every device on you network be synchronised together but your network will be synchronised with every other network on Earth that is hooked up to UTC.

• Control: With a NTP server you have control of the configuration. You can allow automatic changes each spring and autumn for daylight saving time or set your server time to be locked to UTC time only – or indeed, any time zone you choose.

• Automatic update of time. No user intervention required, a NTP time server will account for leap seconds and time zones ensuring trouble free synchronisation.

Benefits of Accurate Network Time Synchronization

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Your computer probably does hundreds and thousands of tasks a day. If that is part of a network then the number of tasks could be millions. From sending emails to saving data, and everything else your computer is tasked to do, they are all logged by the computer or server.

Computers use timestamps to logo processes and indeed, timestamps are used as the only method a computer has to indicate when and if a task or application has been conducted. Timestamps are normally a 16 or 32 bit integer (one long number) that counts back the seconds from a prime epoch – normally 01 January 1970.

So for every task you computer does it will be stamped with the number of seconds from 1970 that the transaction was conducted. These timestamps are the only piece of information a computer system has to ascertain what tasks have been completed and what tasks have yet to be instigated.

The problem with computer networks of more than one machine is that the clocks on individual devices are not accurate enough for many modern time sensitive applications. Computer clocks are prone to drift they are typically based on inexpensive crystal oscillator circuits and can often drift by over a second a day.

This may not seem much but in today’s time sensitive world a second can be a long time indeed especially when you take into account the needs of industries like the stock exchange where a second can be the difference in price of several percent or online seat reservation, where a second can make the difference between an available seat and one that is sold.

This drift is also accumulative so within only a few months the computer systems could be over a minute out of sync and this can have dramatic effects on time sensitive transactions and can result in all sorts of unexpected problems from emails not arriving as a computer thinks they have arrived before they have been sent to data not being backed up or lost completely.

A NTP time server or network time server are increasingly becoming crucial pieces of equipment for the modern computer network. They receive an accurate source of time from an atomic clock and distribute it to all devices on the network. As atomic clocks are incredibly accurate (they won’t drift by a second even in a 100,000 years) and the protocol NTP (Network Time Protocol) continually checks the devices time against the master atomic clock time – it means the computer network will be able to run perfectly synchronised with each device within a few milliseconds of the atomic clock.

Life Without the Atomic Clock

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When we consider the most important inventions of the last 100 years, very few people will think of an atomic clock. In fact, if you ask somebody to come up with a top ten of inventions and innovations its doubtful if the atomic clock would figure at all.

Its probably not hard to imagine what people think of as the most life-changing inventions: the Internet, mobile phones, satellite navigation systems, media players etc.

However, nearly all theses technologies rely on accurate and precise time and they would not function without it. The atomic clocks lies at the heart of many of the modern innovations, technologies and applications associated with them.

Let’s take the Internet as an example. The Internet is, in its simplest form, a global network of computers, and this network spans time zones and countries. Now consider some of the things we use the Internet for: online auctions, Internet banking or seat reservation for example. These transactions could not be possible with precise and accurate time and synchronisation.

Imagine booking a seat on an airline at 10am and then another customer tries to book the same seat after you on a computer with a slower clock. The computer only has the time to go on so will consider the person who booked after you to have been the first customer because the clock says so! This is the reason any Internet network that requires time sensitive transactions is connected to a NTP server to receive and distribute an atomic clock time signal.

And for other technologies the atomic clock is even more crucial. Satellite navigation (GPS) is a prime example. GPS (Global Positioning System) works by triangulating atomic clock signals from satellites. Because of the high velocity of radio waves an inaccuracy of 1 second could see a sat-nav device out by 100,000 km.

Other technologies too from mobile phone networks to air traffic control systems are completely reliable on atomic clocks demonstrating how underrated this technology is.