Category: Time Synchronisation

Step by Step Installing A Dedicated NTP Time Server

  |   By

A time server is a crucial piece of kit for any network. Time synchronisation is imperative in keeping a network secure and reliable. Time synchronisation, however, need not be the headache many administrators assume it is going to be.

Most of the difficulties of time synchronisation have been taken care of thanks to the protocol NTP (Network Time Protocol). Whilst NTP is not the only time synchronisation software available it is by far the most widely used (due mainly to the fact that it has been around since the 1980’s and is still being developed today).

NTP uses a single time source and distributes it from machine-to-machine checking each PC or device for drift then adjusting for it. NTP is normally installed on Windows and Linux systems (or at least a simplified version called SNTP) although it is freely downloadable from the NTP homepage. While NTP can quite easily receive any time source from the Internet this can cause major security issues no to mention a lack of accuracy that many online NTP servers suffer from.

The most accurate and secure method is to use an external network time server as these sit within the firewall. They also receive a UTC (Coordinated Universal Time) reference direct from an atomic clock which makes them stratum 1 devices. Most internet time servers are stratum 2 servers. NTP uses strata to define how far away a server is from the source so an atomic clock is a stratum 0 device while a computer that receives time direct from a NTP server becomes a stratum 2 device and so on.

The only decision that really needs to be made when installing a dedicated NTP time server is which time reference is best. There are two main methods of receiving a secure, accurate and authenticated UTC time reference; the GPS network (Global Positioning System) or national physics laboratories long wave radio transmissions.

The latter system is not available in every country although the USA, UK and Germany have strong signals known as WWVB, MSF and DCF respectively. These can often be picked up outside the borders of these countries although the signals are vulnerable to interference, outages and local topography.

A GPS NTP server system is less vulnerable to these things and as long as there is a clear view of the sky (such as a rooftop or open window) the GPS time signal can be picked up anywhere on the globe.

Useful NTP server related resources

  |   By

NTP homepage–  The home for the NTP Project who provides support and additional development resources for the Official Reference Implementation of NTP.

NTP Project support pages

THE NTP pool – list of public servers

NPL – The National Physical Laboratory in the UK who control the MSF radio signal.

The University of Delaware and David Mills’ information page, Professor Mills is the original inventor and developer of NTP

David Mills’ list of Public NTP Time Servers a list of public NTP servers

National Institute of Standards and Technology (NIST) who operate the USA’s WWVB radio signal

Europe’s largest supplier of NTP server related products.

Galleon UK – NTP server products for the UK

NTP Time Server .com  – one of the largest time and frequency suppliers in the United States

NTP – Wikipedia article on NTP

NTP server checker – free tool to ensure time server accuracy

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

  |   By

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.

NTP Server Time Tired of Inaccurate and Insecure Time

  |   By

The internet has been a marvellous resource for business over the last decade. High speed access and the proliferation of computers in homes and offices alike have turned the World Wide Web into the main business arena for many companies.

With more and more transactions being conducted from opposite ends of the world across the internet, the need for an accurate and precise clock to keep computer networks synchronised has never been greater.

Most of the world’s computer networks, synchronise to a source of UTC (Coordinated Universal Time) which is the worldwide standard and is controlled by atomic clocks. A worldwide standard for synchronising the clocks has been developed also. NTP (Network Time Protocol) is a software algorithm that distributes UTC amongst a network’s clocks and adjusts the time accordingly.

Many computer network administrators turn to the internet as a source of NTP server time as there are a multitude of sources of UTC time. However, many internet sources of NTP time cannot be relied upon to provide accurate time. Surveys have discovered more than half of all internet time servers were inaccurate by over a second and even those that are not, they could be too far away to provide any useful precision.

More importantly, however, is that internet based NTP servers are external to a network’s firewall so any regular communication with a NTP server will require the firewall port to be left open allowing easy access for malicious users to take advantage of.

The only solution for getting a source of NTP server time, whilst keeping a network secure, is to use an external stratum 1 NTP time server. These devices communicate directly with an atomic clock either via the GPS satellite network or long wave radio signals. Because these devices operate from with the firewall the entire network is kept secure whilst the NTP server distributes an accurate, precise and source of UTC time.

Time Server Synchronisation The basics

  |   By

NTP (Network Time Protocol) is an internet based protocol designed to synchronise the clocks on a computer network. It is the main time synchronisation software used in computer networks and is also packaged with most operating systems.

An NTP server is a dedicated device that receives a single time source then distributes it amongst all devices on a network. The protocol NTP monitors the drift of the internal clocks on a network and corrects for them.

An NTP server can receive a time source from either a national physical laboratory such as the UK’s National Physical Laboratory (NPL), however, these time signals are broadcast via long wave radio and have finite range.

GPS NTP servers are designed to receive the time source generated by the atomic clocks onboard GPS satellites (Global Positioning System). GPS is available anywhere on the planet as a time source as long as there is a clear view of the sky.

Without correct synchronisation all sorts of potential problems can occur such as leaving a computer system vulnerable to fraud, malicious users and hackers. An unsynchronised computer network may also lose data and be difficult to audit.

A global timescale called UTC (Coordinated Universal Time) has been developed to ensure the entire world uses the same timescale. The NTP server utilise UTC ensuring the computer network is telling the same time as every other computer network.

(UTC) Coordinated Universal Time is The only time you will ever need to know

  |   By

We may think of their being only one time and therefore one timescale. Sure, we’re all aware of time zones where the clock has to be pushed back an hour but we all obey the same time surely?

Well actually we don’t. There are numerous different timescales all developed for different reasons are too numerous to mention them all but it wasn’t until the nineteenth century that the idea of a single timescale, used y everybody came into effect.

It was the advent of the railway that provoked the first national timescale in the UK (Railway time) before then people would use noon as a basis for time and set their clocks to it. It rarely mattered if your watch was five minutes faster than your neighbours but the invention of the trains and the railway timetable soon changed all that.

The railway timetable was only useful if people all used the same time scale. A train leaving at 10.am would be missed if a watch was five minutes slow so synchronisation of time became a new obsession.

Following railway time a more global timescale was developed GMT (Greenwich Meantime) which was based on the Sun’s position at noon which fell over the Greenwich Meridian line (0 degrees longitude). It was decided during a world conference in 1884 that a single world meridian should replace the numerous one’s already in existence. London was perhaps the most successful city in the world so it was decided the best place for it.

GMT allowed the entire world to synchronise to the same time and while nations altered their clocks to adjust for time-zones their time was always based on GMT.

GMT proved a successful development and remained the world’s global timescale until the 1970’s. By then that atomic clock had been developed and it was discovered in the use of these devices that Earth’s rotation wasn’t a reliable measure to base our time on as it actually alters day by day (albeit by fractions of a second).

Because of this a new timescale was developed called UTC (Coordinated Universal Time). UTC is based on GMT but allows for the slowing of the Earth’s rotation by adding additional ‘Leap Seconds’ to ensure that Noon remains on the Greenwich Meridian.

UTC is now used all over the World and is essential for applications such as air traffic control, satellite navigation and the Internet. In fact computer networks across the globe are synchronised to UTC using NTP time servers (Network Time Protocol). UTC is governed by a constellation of atomic clocks controlled by national physics laboratories such as NIST (National Institute of Standards and Time) and the UK’s NPL.

The Atomic Clock and the Network Time Server

  |   By

The atomic clock is the culmination of mankind’s obsession of telling accurate time. Before the atomic clock and the nanosecond accuracy they, employ time scales were based on the celestial bodies.

However, thanks to the development of the atomic clock it has now been realised that even the Earth in its rotation is not as accurate a measure of time as the atomic clock as it loses or gains a fraction of a second each day.

Because of the need to have a timescale based somewhat on the Earth’s rotation (astronomy and farming being two reasons) a timescale that is kept by atomic clocks but adjusted for any slowing (or acceleration) in the Earth’s spin. This timescale is known as UTC (Coordinated Universal Time) as employed across the globe ensuring commerce and trade utilise the same time.

Computer networks use network time servers to synchronise to UTC time. Many people refer to these time server devices as atomic clocks but that is inaccurate. Atomic clocks are extremely expensive and highly sensitive pieces of equipment and are only usually to be found in universities or national physics laboratories.

Fortunately national physics laboratories like NIST (National Institute for Standards and Time – USA) and NPL (National Physical Laboratory – UK) broadcast the time signal from their atomic clocks. Alternatively the GPS network is another good source of accurate time as each GPS satellite has onboard its own atomic clock.

The network time server receives the time from an atomic clock and distributes it using a protocol such as NTP (Network Time Protocol) ensuring the computer network is synchronised to the same time.

Because network time servers are controlled by atomic clocks they can keep incredibly accurate time; not losing a second in hundreds if not thousands of years. This ensures that the computer network is both secure and unsusceptible to timing errors as all machines will have the exact same time.

A History of Atomic Clocks

  |   By

The atomic clock is the culmination of mankind’s ability to keep time that has spanned several millennia. Humans have always been preoccupied with keeping track of time ever since early man noticed the regularity of the celestial bodies.

The sun, moon, stars and planets soon became the basis for out timescales with periods of time such as years, months, days and hours based solely on the regulation of the Earth’s rotation.

This worked for thousands of years as a reliable guide to how much time has past but over the last few centuries humans have strode to find even more reliable methods for keeping track of time. Whilst the Sun and celestial bodies were an affective way sundials didn’t work on cloudy days and as the days and night s altered during the year only noon (when the sun is at its highest) could be reasonably relied upon.

The first foray into an accurate timepiece that was not reliant on celestial bodies and was not a simple time (such as a candle taper or water clock) but actually told time over a prolonged period was the mechanical clock.

These first devices dating as far back as the twelfth century were crude mechanisms using a verge and foliot escapement (a gear and lever) to control the ticks of the clock. After a few centuries and a myriad of designs the mechanical clock took its next step forward with the pendulum. The pendulum gave clocks their first true accuracy as it controlled with more precision the ticks of the clock.

However, it wasn’t until the twentieth century when clocks entered the electronic age did they become truly accurate. The digital and electronic clock had its ticks controlled by using the oscillation of a quartz crystal (its changed energy state when a current is based through) which proved so accurate that rarely a second a week was lost.

The development of atomic clocks in the 1950’s used the oscillation of a single atom which generates over 9 billion ticks a second and can maintain precise time for millions of years without losing a second. These clocks now form the basis of our timescales with the entire world synchronised to them using NTP servers, ensuring wholly accurate and reliable time.

The NTP Server and Understanding Timescales

  |   By

There are several timescale used throughout the world. Most NTP servers and other network time servers use UTC as a base source however, there are others:

When we are asked the time it is very unlikely we would respond with ‘for which timescale’ yet there are several timescales used all over the globe and each is based on different methods of keeping track of the time.
GMT

Greenwich Mean Time (GMT) is the local time on the Greenwich meridian based on the hypothetical mean sun. As the Earth’s orbit is elliptical and its axis is tilted, the actual position of the sun against the background of stars appears a little ahead or behind the expected position. The accumulated timing error varies through the year in a smoothly periodic manner by up to 14 minutes slow in February to 16 minutes fast in November. The use of a hypothetical mean sun removes this effect. Before 1925 astronomers and navigators measured GMT from noon to noon, starting the day 12 hours later than in civil usage which was also commonly referred to as GMT. To avoid confusion astronomers agreed in 1925 to change the reference point from noon to midnight, and a few years later adopted the term Universal Time (UT) for the “new” GMT. GMT remains the legal basis of the civil time for the UK.

UT

Universal Time (UT) is mean solar time on the Greenwich meridian with 0 h UT at mean midnight, and since 1925 has replaced GMT for scientific purposes. By the mid-1950s astronomers had much evidence of fluctuations in the Earth’s rotation and decided to divide UT into three versions. Time derived directly from observations is called UT0, applying corrections for movements of the Earth’s axis, or polar motion, gives UT1, and removing periodic seasonal variations generates UT2. The differences between UT0 and UT1 are of the order of thousandths of a second. Today, only UT1 is still widely used as it provides a measure of the rotational orientation of the Earth in space..


The world time standard (UTC):

Although TAI provides a continuous, uniform, and precise time scale for scientific reference purposes, it is not convenient for everyday use because it is not in step with the Earth’s rate of rotation. A time scale that corresponds to the alternation of day and night is much more useful, and since 1972, all broadcast time services distribute time scales based on Coordinated Universal Time (UTC). UTC is an atomic time scale that is kept in agreement with Universal Time. Leap seconds are occasionally

Information courtesy of the National Physical Laboratory UK.

Leap Second Errors and Configuration

  |   By

Apart from the usual celebrations and revelry the end of December brought with the addition of another Leap Second to UTC time (Coordinated Universal Time).

UTC is the global timescale used by computer networks across the world ensuring that everybody is keeping the same time. Leap Seconds are added to UTC by the International Earth Rotation Service (IERS) in response to the slowing of the Earth’s rotation due to tidal forces and other anomalies. Failure to insert a leap second would mean that UTC would drift away from GMT (Greenwich Meantime) – often referred to as UT1. GMT is based on the position of the celestial bodies so at midday the sun is at its highest above the Greenwich Meridian.

If UTC and GMT were to drift apart it would make life difficult for people like astronomers and farmers and eventually night and day would drift (albeit in a thousand years or so).

Normally leap seconds are added to the very last minute of December 31 but occasionally if more than one is required in a year then is added in the summer.

Leap seconds, however, are controversial and can also cause problems if equipment isn’t designed with leap seconds in mind. For instance, the most recent leap second was added on 31 December and it caused database giant Oracle’s Cluster Ready Service to fail. It resulted in the system automatically rebooting itself on New Year.

Leap Seconds can also cause problems if networks are synchronised using Internet time sources or devices that require manual intervention.  Fortunately most dedicated NTP servers are designed with Leap Seconds in mind. These devices require no intervention and will automatically adjust the entire network to the correct time when there is a Leap Second.

A dedicated NTP server is not only self-adjusting requiring no manual intervention  but also they are highly accurate being stratum 1 servers (most Internet time sources are stratum 2 devices in other words devices that receive time signals from stratum 1 devices then reissue it) but they are also highly secure being external devices not required to be behind the firewall.