Posted by Richard N Williams on October 12th, 2009
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.
Posted by Richard N Williams on October 10th, 2009
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.
Posted by Stuart on October 8th, 2009
For those of us that live in Britain, the CCTV camera (closed circuit TV) will be a familiar site on the high streets. Over four million cameras are in operation throughout the British Isles with every major city being monitored by state funded cameras which has cost the British taxpayer over £200 million ($400 million).
The reasons for use of such widespread surveillance have always been declared as to prevent and detect crime. However, critics argue that there is little evidence that CCTV cameras have done anything to dent the rising street crime on the UK’s streets and that the money could be better well spent.
One of the problems of CCTV is that many cities have both cameras controlled by local councils and privately controlled cameras. When it comes to crime detection the police often have to obtain as much evidence as possible which often means combining the different local authority controlled CCTV cameras with the privately controlled systems.
Many local authorities synchronise their CCTV cameras together, however, if the police have to obtain images from a neighbouring borough or from a private camera these may not be synchronised at all, of if so, synchronised to a different time completely.
This is where CCTV falls down in the fight against crime. Just imagine a suspected criminal is spotted on one CCTV camera committing a criminal act. The time on the camera could say 11.05pm but what if the police follow the suspects movements across a city and use footage from a privately owned camera or from other boroughs and while the CCTV camera that caught the suspect in the act may say 11.05, the other camera could spot the suspect minutes later only for the time to be even earlier. You could imagine a good defence lawyer taking full advantage of this.
To ensure their worth in the fight against crime, it is imperative that CCTV cameras are time synchronized using a network time server. These times servers ensure every device (in this case camera) is running the exact same time. But how do we ensure all cameras are synchronised to the same time source. Well fortunately, a global time source known as UTC (coordinated Universal Time) has been developed for this exact purpose. UTC is what governs computer networks, air traffic control and other time sensitive technologies.
A CCTV camera using a NTP server that receives a UTC time source from an atomic clock will not only be accurate but the time told on the devices will be provable in court and accurate to a thousandth of a second (millisecond).
Posted by Stuart on October 6th, 2009
Remember the turn of the millennium. Whilst many of us were counting down the seconds until midnight, there were network administrators across the globe with their fingers crossed hoping their computer systems will still be working after the new millennium kicked in.
The millennium bug was the result of early computer pioneers designing systems with only two digits to represent the time as computer memory was very scarce at the time. The problem didn’t arise because of the turn of the millennium, it arose because it was the end of the century and two digit year flicked around to 00 (which the machines assume was 1900)
Fortunately by the turn of the millennium most computers were updated and enough precautions were taken that meant that the Y2K bug, as it became known, didn’t cause the widespread havoc it was first feared.
However, the Y2K bug is not the only time related problem that computer systems can be expected to face, another problem with the way computers tell the time has been realised and many more machines will be affected in 2038.
The Unix Millennium Bug (or Y2K38) is similar to the original bug in that it is a problem connected with the way computers tell the time. The 2038 problem will occur because most machines use a 32 bit integer to calculate the time. This 32 bit number is set from the number of seconds from 1 January 1970, but because the number is limited to 32 digits by 2038 there will be no more digits left to deal with the advance of time.
To solve this problem, many systems and languages have switched to a 64-bit version, or supplied alternatives which are 64-bit and as the problem will not occur for nearly three decades there is plenty of time to ensure all computer systems can be protected.
However, these problems with timestamps are not the only time related errors that can occur on a computer network. One of the most common causes of computer network errors is lack of time synchronization. Failing to ensure each machine is running at an identical time using a NTP time server can result in data being lost, the network being vulnerable to attack from malicious users and can cause all sorts of errors such as emails arriving before they have been sent.
To ensure your computer network is adequately synchronized an external NTP time server is recommended.
Posted by Stuart on September 30th, 2009
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?
Posted by Richard N Williams on September 26th, 2009
There is nothing worse than returning to your car only to discover that your parking meter time limit has expired and you’ve got a parking ticket slapped on to your windscreen.
More-often-than-not it’s only a matter of being a couple of minutes late before an over eager parking attendant spots your expired meter or ticket and issues you a fine.
However, as the people of Chicago are discovering, whilst a minute may be the difference between getting back to the car in time or receiving a ticket, a minute may also be the difference between different parking meters.
It seems the clocks on the 3000 new parking meter pay boxes in Cale, Chicago have been discovered to be unsynchronized. In fact, of the nearly 60 pay boxes observed, most are off at least a minute and in some cases, nearly 2 minutes from what is “actual” time.
This has posed a headache to the firm in charge of parking in the Cale district and they could face legal challenges from the thousands of motorists that have been given tickets from these machine.
The problem with the Cale parking system is that while they claim they regularly calibrate their machine there is no accurate synchronization to a common time reference. In most modern applications UTC (Coordinated Universal Time) is used as a base timescale and to synchronize devices, like Cale’s parking meters, a NTP server, linked to an atomic clock will receive UTC time and ensure every device has the exact time.
NTP servers are used in the calibration of not just parking meters but also traffic lights, air traffic control and the entire banking system to name but a few applications and can synchronize every device connected to it to within a few milliseconds of UTC.
It’s a shame Cale’s parking attendants didn’t see the value of of a dedicated NTP time server – I’m sure they are regretting not having one now.
Posted by Richard N Williams on September 24th, 2009
Dedicated NTP time server devices are the easiest, most accurate, reliable and secure method of receiving a source of UTC time (Coordinated Universal Time) for synchronizing a computer network.
NTP servers (Network Time Protocol) operate outside the firewall and are not reliant on the Internet which means they are highly secure and not vulnerable to malicious users who, in the case of Internet time sources can use the NTP client signals as a method of accessing the network or penetrating the firewall.
A dedicated NTP server will also receive it’s time code direct from an atomic clock, this makes it a stratum 1 time server as opposed to online time servers which are stratum 2 time servers, that is they get the time from a stratum 1 server and so are not as accurate.
In using a NTP time server there is only really one decision to make and that is how the time signal is to be received and for this there is only two choices:
The first is to make use of the time standard radio transmissions broadcast by national physics laboratories such as NIST in the USA or the UK’s NPL. These signals (WWVB in the US, MSF in the UK) are limited in range although the USA signal is available in most parts of Canada and Alaska. However, they are vulnerable to local interference and topography as other long wave radio signals are.
The alternative to the WWVB/MSF signal is to utilise the GPS satellite network (Global Positioning System). Atomic clocks are used by GPS satellites as the basis for navigational information used by satellite receivers. These atomic clocks can be used by using a NTP time server fitted with a GPS antenna.
Whilst the GPS time signal is strictly speaking not UTC- it is 17 seconds behind as leap seconds have never been added to GPS time (as the satellites are unreachable) but NTP can account for this (by simply adding 17 whole seconds). The advantage of GPS is that it is available anywhere on the planet just as long as the GPS antenna has a clear view of the sky.
Duel systems that can utilise both types of signal are also available.
Posted by Stuart on September 3rd, 2009
NTP (Network Time Protocol) is the protocol designed for time distribution amongst a network. NTP is hierarchical. It organises a network into strata, which are the distance from a clock source and the device.
A dedicated NTP server that receives the time from a UTC source such as GPS or the national time and frequency signals is regarded as a stratum 1 device. Any device that is connected to a NTP server becomes a stratum 2 device and devices farther down the chain become stratum 2, 3 and so on.
Stratum layers exist to prevent cyclical dependencies in the hierarchy. But the stratum level is not an indication of quality or reliability.
NTP checks the time on all devices on the network it then adjusts the time according to how much drift it discovers. Yet NTP goes further than just checking the time on a the reference clock, the NTP program exchanges time information by packets (blocks of data) but refuses to believe the time it is told until several exchanges have taken place, each passing a set of tests known asprotocol specifications. It often takes about five good samples until a NTP server is accepted as a timing source.
NTP uses timestamps to represent the current time the day. As time is linear, each timestamp is always greater than the previous one. NTP timestamps are in two formats but they relay the seconds from a set point in time (known as the prime epoch, set at 00:00 1 January 1900 for UTC) The NTP algorithm then uses this timestamp to determine the amount to advance or retreat the system or network clock.
NTP analyses the timestamp values including the frequency of errors and the stability. A NTP server will maintain an estimate of the quality of both its reference clocks and itself.
Posted by Stuart on September 1st, 2009
Keeping your network synchronized with the correct time is crucial for modern networking. Because of the value of timestamps in communciating globally and across multi-networks, it is imperative that every machine is running a source of UTC (Coordinated Universal Time).
UTC was developed to allow the entire global community to use the same time no matter where they are on the globe as UTC doesn’t use time-zones so it allows accurate communication regardless of location.
However, finding a source of UTC is often where some network administrators fall down when they are attempting to synchronize a network. There are many areas that a source of UTC can be received from but very few that will provide both accurate and secure reference to the time.
The internet is full of purported sources of UTC, however, many of them offer no where near their acclaimed accuracy. Furthermore, resorting to the internet can lead to security vulnerabilities.
Internet time sources are external to the firewall and therefore a hole has to be left open which can be taken advantage of by malicious users. Furthermore, NTP, the protocol used to distribute and receive time sources, cannot instigate its authentication security measure across the internet so it is not possible to ensure the time is coming from where it is supposed to.
External sources of UTC time are far more secure. There are two methods used by most administrators. Long wave radio signals as broadcast by national physics laboratories and the GPS signal which is available everywhere on the globe.
The external sources of UTC ensure your NTP network is receiving not just an accurate source of UTC but also a secure one.
Posted by Richard N Williams on August 26th, 2009
Atomic clocks have, unbeknown to most people, revolutionised our technology. Many of the ways we trade, communicate and travel are now solely dependent on timing from atomic clock sources.
A global community often means that we have to communicate with people on other areas of the world and in other time zones. For this purpose a universal time zone was developed, known as UTC (Coordinated Universal Time), which is based on the time told by atomic clocks.
Atomic clocks are incredibly accurate, losing only a second in every hundred million years, which is staggering when you compare it to digital clocks that will lose that much time in a week.
But why do we need such accuracy in timekeeping? Much of the technology we employ in modern times is designed for global communication. The Internet is a good example. So much trade is done across continents in fields such as the stock exchange, seat reservation and online auctioning that exact time is crucial. Imagine you are bidding for an item on the Internet and you place a bid a few seconds before the end, the last and highest bid, would it be fair to lose the item because the clock on your ISP was a little fast and the computer therefore thought the bidding was over. Or what about seat reservation; if two people on different sides of the globe book a seat at the same time, who gets the seat. This is why UTC is vital for the internet.
Other technologies too such as global positioning and air traffic control are reliant on atomic clocks to provide accuracy (and in the case of air traffic is paramount for safety). Even traffic lights and speed cameras have to be calibrated with atomic clocks otherwise speeding ticket may not be valid as they could be questioned in court.
For computer systems NTP time servers are the preferred method for receiving and distributing a source of UTC time.