UTC What Time is it?

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From the early days of the industrial revolution, when railway lines and the telegraph spanned across time zones it became apparent that a global timescale was required that would allow the same time to be used no matter where you were in the world.

The first attempt at a global timescale was GMT – Greenwich Meantime. This was based on the Greenwich Meridian where the sun is directly above at 12 noon. GMT was chosen, primarily because of the influence of the British empire on the rest if the globe.

Other timescales had been developed such British Railway Time but GMT was the first time a truly global system of time was used throughout the world.

GMT remained as the global timescale through the first half of the twentieth century although people began referring to as UT (Universal Time).

However, when atomic clocks were developed in the middle of the twentieth century it soon became apparent that GMT was not accurate enough. A global timescale based on the time told by atomic clocks was desired to represent these new accurate chronometers.

International Atomic Time (TAI) was developed for this purpose but problems in using atomic clocks soon became apparent.

It was thought that the Earth’s revolution on its axis was an exact 24 hours. But thanks to atomic clocks it was discovered the Earth’s spin varies and since the 1970’s has been slowing. This slowing of the Earth’s rotation needed to be accounted for otherwise the discrepancies could build up and night would slowly drift in to day (albeit in many millennia).

Coordinated Universal Time was developed to counter this. Based on both TAI and GMT, UTC allows for the slowing of the Earth’s rotation by adding leap seconds every year or two (and sometimes twice a year).

UTC is now a truly global timescale and is adopted by nations and technologies across the globe. Computer networks are synchronised to UTC via network time servers and they use the protocol NTP to ensure accuracy.

Radio Controlled Clocks Atomic Clocks on Shortwave

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Atomic clocks are a marvel compared to other forms of timekeepers. It would take over 100,000 years for an atomic clock to lose a second in time which is staggering especially when you compare it to digital and mechanical clocks that can drift that much in a day.

But atomic clocks are not practical pieces of equipment to have around the office or home. They are bulky, expensive and require laboratory conditions to operate effectively. But making use of an atomic clock is straightforward enough especially as atomic time keepers like NIST (National Institute of Standards and Time) and NPL (National Physical Laboratory) broadcast the time as told by their atomic clocks on short wave radio.

NIST transmits its signal, known as WWVB from Boulder, Colorado and it is broadcast on an extremely low frequency (60,000 Hz). The radio waves from WWVB station can cover all of the continental United States plus much of Canada and Central America.

The NPL signal is broadcast in Cumbria in the UK and it is transmitted along similar frequencies. This signal, known as MSF is available throughout most of the UK and similar systems are available in other countries such as Germany, Japan and Switzerland.

Radio controlled atomic clocks receive these long wave signals and correct themselves according to any drift the clock detects. Computer networks also take advantage of these atomic clocks signals and use the protocol NTP (Network Time Protocol) and dedicated NTP time servers to synchronise hundreds and thousands of different computers.

IEEE 1588 Time Protocol Promises More Accurate Time Synchronisation

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Despite being around for over twenty years, the current favoured time protocol by most networks, NTP (Network Time Protocol) has some competition.

Currently NTP is used to synchonise computer networks using network time servers (NTP servers). Currently NTP can synchronise a computer network to a few milliseconds.

The Precision Time Protocol (PTP) or IEEE 1588 has been developed for local systems requiring very high accuracy (to nano-second level). Currently this type of accuracy is beyond the capabilities of NTP.

PTP requires a master and slave relation ship in the network. A two-step process is required to synchronise devices using the IEEE 1588 (PTP). First, determination of which device is the master is required then the offsets and natural network delays are measured. PTP uses the Best Master Clock algorithm (BMC) to establish which clock on the network is the most accurate and it becomes the master whilst all other clocks become slaves and synchronise to this master.

IEEE (Institute of Electrical and Electronic Engineers) describes IEEE 1588 or (PTP) as designed to “fill a niche not well served by either of the two dominant protocols, NTP and GPS.  IEEE 1588 is designed for local systems requiring very high accuracies beyond those attainable using NTP. It is also designed for applications that cannot bear the cost of a GPS receiver at each node, or for which GPS signals are inaccessible.” (quoted in Wikipedia)

PTP can provide accuracy to a few nano-seconds but this type of accuracy is not required by most network users however, the target use of PTP appears to be mobile broadband and other mobile technologies as PTP supports time-of-day information, used by billing and service level agreement reporting functions in mobile networks.

A Brief History of Computer Time

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Telling the time is something may of us learn when we are very small children. Knowing what time it is is an essential part of our society and we couldn’t function without it. Just imagine if we didn’t tell the time – when would you go to work? When would you leave and how would it be possible to meet other people or arrange any kind of function.

While telling the time is crucial to us, it is even more vital for computers who use time as the only point of reference and amongst computer networks time synchronisation is vital. Without recording the passing of time, computers couldn’t function as there would be no reference to order programs and functions.
But the way computers tell the time and date is far different to the way we record it. Rather than record a separate time, date and year – computer systems use a single number. This number is based on the number of seconds from a set point in time – known as the prime epoch.

When this epoch is, depends on the operating system or programming language in question. For instance, Unix systems have a prime epoch which starts at 1 January 1970 and the number of seconds from the epoch are counted in a 32 bit integer. Other operating systems, such as Windows, use a similar system but the epoch is different (Windows starts on 1 January 1601).

There are, however, disadvantages to this integer system. For instance as the Unix system is a 32-bit integer which started in 01 Jan 1970, by 19 January 2038 the integer will have exhausted every possible number and will have to return to zero’s. This could cause problems with systems reliant on Unix in a problem reminiscent of the Millennium bug.
There are other issues involving computer time also. Because of the global requirements of the Internet all computer time is now based on UTC (Coordinated Universal Time). However, UTC is altered on occasion by adding Leap Seconds to ensure the time matches the rotation of the Earth (the Earth’s rotation is never exact due to gravitational forces) so leap second handling has to be encompassed into a computer time systems.

Computer time is often associated with NTP (Network Time Protocol) which is used to synchronise computers often using a network time server.

Common Time Synchronization Pitfalls Finding UTC

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Time synchronization can be a headache for many network administrators attempting to synchronize a network for the first time. There are many pitfalls that an unaware network administrator can fall into when attempting to get every machine on a network to synchronize to the same time.

The first problem many network administrators make is the selection of the time source. UTC (Coordinated Universal Time) is a global timescale and is used throughout the world as a basis for time synchronization as it doesn’t rely on time zones enabling the global community to base itself on one timescale.

UTC is also controlled by a constellation of atomic clocks which ensures its accuracy; however, it is regularly adjusted to ensure that it matches mean solar time by the addition of leap seconds which are added to counter the natural slowing of the Earth’s rotation.

UTC is readily available as a time reference from a number of sources. The Internet is a popular location to receive a UTC time source. However, an Internet time source is located through the network firewall and security issues can arise from having to leave the UDP port open to receive the time requests.

Internet time sources can also be inaccurate and as NTP’s own security system known as NTP authentication cannot work across the Internet further security issues can arise.

A far better solution for getting a source of UTC is to use either the Global Positioning System (GPS) or the long wave radio transmissions broadcast by several national physics laboratories such as NIST in the USA and the UK’s NPL.

Dedicated NTP time servers can receive these secure and authenticated signals and then distribute them amongst all devices on a network.

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.

Europes GPS System is starting to Take Shape

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Following years of wrangling and uncertainty, the European equivalent to the GPS (Global Positioning System), is finally beginning to take shape. The European Galileo system, which will complement the current USA system, is a step closer to completion.

Galileo, which will be the first operational global navigational satellite system (GNSS) outside the United States will provide positioning information for satellite navigation machines and timing information for GPS NTP servers (Network Time Protocol).

The system, being designed and manufactured by the European Space Agency (ESA) and the European Union (EU) and when it is operational it is expected to improve the availability and accuracy of timing and navigation signals transmitted from space.

They system has been dogged in political wrangling and uncertainty since its inception nearly a decade ago. Objections from the US that they will lose the ability top switch off GPS in times of military need; and economic restraints across Europe, meant that the project was nearly shelved several times.

However, the first four satellites are being finalised in a laboratory in southern England. These In-Orbit Validation (IOV) satellites will form a mini-constellation in the sky and prove the Galileo concept by transmitting the first signals so the European system can become a reality.

The rest of the satellite network should follow shortly after and. Galileo should eventually comprise over 30 of them which means that users of satellite navigation systems of GPS NTP time servers should get quicker fixes be able to locate their positions with an error of one metre compared with the current GPS-only error of five.

The Way an Atomic Clock Works

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Atomic clocks are the most accurate chronometers we have. They are millions of times more accurate than digital clocks and can keep time for hundreds of millions of years without losing as much as a second. Their use has revolutionised the way we live and work and they have enabled technologies such as satellite navigation systems and global online commerce.

But how do they work? Strangely enough, atomic clocks work in the same way as ordinary mechanical clocks. But rather than have a coiled spring and mass or pendulum they use the oscillations of atoms. Atomic clocks are not radioactive as they do not rely on atomic decay instead they rely on the tiny vibrations at certain energy levels (oscillations) between the nucleus of an atom and the surrounding electrons.

When the atom receives microwave energy at exactly the right frequency, it changes energy state, this state is constant an unchanging and the oscillations can be measured just like the ticks of a mechanical clock. However, while mechanical clocks tick every second, atomic clocks ‘tick’ several billion times a second. In the case of caesium atoms, most commonly used in atomic clocks, they tick 9,192,631,770 per second – which is now the official definition of a second.

Atomic clocks now govern the entire global community as a universal timescale UTC (Coordinated Universal Time) based on atomic clock time has been developed to ensure synchronization. UTC atomic clock signals can be received by network time servers, often referred to as NTP Servers, that can synchronize computer networks to within a few milliseconds of UTC.

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.

Keeping Your Network Secure A Beginners Guide

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Network security is vitally important for most business systems. Whilst email viruses and denial-of-service attacks (DoS attack) may cause us headaches on our home systems, for businesses, these sorts of attacks can cripple a network for days – costing businesses hundreds of millions each year in lost revenue.

Keeping a network secure to prevent this type of malicious attack is usually of paramount importance for network administrators, and while most invest heavily in some forms of security measures there is often vulnerabilities inadvertently left exposed.

Firewalls are the best place to begin when you are trying to develop a secure network. A firewall can be implemented in either hardware or software, or most commonly a combination of both. Firewalls are used to prevent unauthorized users from accessing private networks connected to the Internet, especially local intranets. All traffic entering or leaving the intranet pass through the firewall, which examines each message and blocks those that do not meet the specified criteria.

Anti-virus software works in two ways. Firstly it acts similarly to a firewall by blocking anything that is identified in its database as possibly malicious (viruses, Trojans, spyware etc). Secondly Anti-virus software is used to detect, and remove existing malware on a network or workstation.

One of the most over-looked aspects of network security is time synchronization. Network administrators either fail to realise the importance of synchronization between all devices on a network. Failing to synchronize a network is often a common security issue. Not only can malicious users take advantage of computers running at different times but if a network is struck by an attack, identifying and rectifying the problem can be near impossible if every device is running on a different time.

Even when a network administrator is aware of the importance of time synchronization they often make a common security mistake when attempting to synchronize their network. Instead of investing in a dedicated time server that receives a secure source of UTC (Coordinated Universal Time) externally from their network using atomic clock sources like GPS, some network administrators opt to use a shortcut and use a source of Internet time.

There are two major security issues in using the Internet as a time server. Firstly, to allow the time code through the network a UDP port (123) has to be left open in the firewall. This can be taken advantage of by malicious users who can use this open port as an entrance to the network. Secondly, the inbuilt security measure used by the time protocol NTP, known as authentication, doesn’t work across the Internet which means that NTP has no guarantee the time signal is coming from where it is supposed to.

To ensure your network is secure isn’t it time you invested in an external dedicated NTP time server?