Network Time Protocol (NTP) provides algorithms and defines messages for the synchronisation of time clients to an accurate time reference. This article discusses how to configure a Linux NTP Time Server to synchronise time with an Internet based public NTP Server.NTP server systems fall into two categories: primary reference servers and secondary reference servers. Primary reference servers use an external timing reference to provide time, such as GPS or radio clocks. Secondary reference servers synchronise with primary reference NTP servers and offer slightly reduced accuracy. Primary reference servers are designated stratum 1 servers, while secondary servers have a stratum greater than 1.The NTP DistributionThe NTP source code is freely available from the Network Time Protocol web site. The current version available for download is 4.2.4. NTP is available for the Linux operating systems with ports available for Windows NT. Once the source code is downloaded, it should be configured, compiled and installed on the host machine. Many Linux operating systems, such as RedHat, offer NTP RPM packages.Configuring NTPThe ‘ntp.conf’ file is main source of configuration information for a NTP server installation. Amongst other things, it contains a list of reference clocks that the installation is to synchronise. A list of NTP server references is specified with the ‘server’ configuration command thus:server time-a.nist.gov # NIST, Gaithersburg, Maryland NTP serverserver time-c.timefreq.bldrdoc.gov # NIST, Boulder, Colorado NTP serverControlling the NTP Server DaemonOnce configured, the NTP daemon can be started, stopped and restarted using the commands: ‘ntpd start’; ‘ntpd stop’ and ‘ntpd restart’. The NTP server daemon can be queried using the ‘ntpq –p’ command. The ntpq command queries the NTP server for synchronisation status and provides a list of servers with synchronisation information for each server.NTP Access ControlAccess to the NTP server can be restricted using the ‘restrict’ directive in the ntp.conf file. You can restrict all access to the NTP server with:restrict default ignoreTo only allow machines on your own network to synchronize with the server use:restrict 192.168.1.0 mask 255.255.255.0 nomodify notrapMultiple restrict directives can be specified in the ntp.conf file to restrict access to a specified range of computers.Authentication OptionsAuthentication allows a matching passwords to be specified by the NTP server and associated clients. NTP keys are stored in the ntp.keys file in the following format: Key-number M Key (The M stands for MD5 encryption), e.g.:1 M secret5 M RaBBit7 M TiMeLy10 M MYKEYIn the NTP configuration file ntp.conf, specify which of the keys specified above are trusted, i.e. are secure and you want to use. Any keys specified in the keys file but not trusted will not be used for authentication, e.g.:trustedkey 1 7 10The NTP server is now configured for authentication.Client Configuration for AuthenticationThe client needs to be configured with similar information as the server, however, you may use a subset of the keys specified on the server. A different subset of keys can be used on different clients, e.g.:Client A)1 M secret7 M TiMeLytrustedkey 1 7Client B)1 M secret5 M RaBBit7 M TiMeLy10 M MYKEYtrustedkey 7 10Essentially authentication is used by the client to authenticate that the time server is who he says he is, and that no rogue server intervenes. The key is encrypted and sent to the client by the server where it is unencrypted and checked against the client keys to ensure a match.

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FitLine – more power

Network Time Protocol (NTP) provides algorithms and defines messages for the synchronisation of time clients to an accurate time reference. This article discusses how to configure a Linux NTP Time Server to synchronise time with an Internet based public NTP Server.NTP server systems fall into two categories: primary reference servers and secondary reference servers. Primary reference servers use an external timing reference to provide time, such as GPS or radio clocks. Secondary reference servers synchronise with primary reference NTP servers and offer slightly reduced accuracy. Primary reference servers are designated stratum 1 servers, while secondary servers have a stratum greater than 1.The NTP DistributionThe NTP source code is freely available from the Network Time Protocol web site. The current version available for download is 4.2.4. NTP is available for the Linux operating systems with ports available for Windows NT. Once the source code is downloaded, it should be configured, compiled and installed on the host machine. Many Linux operating systems, such as RedHat, offer NTP RPM packages.Configuring NTPThe ‘ntp.conf’ file is main source of configuration information for a NTP server installation. Amongst other things, it contains a list of reference clocks that the installation is to synchronise. A list of NTP server references is specified with the ‘server’ configuration command thus:server time-a.nist.gov # NIST, Gaithersburg, Maryland NTP serverserver time-c.timefreq.bldrdoc.gov # NIST, Boulder, Colorado NTP serverControlling the NTP Server DaemonOnce configured, the NTP daemon can be started, stopped and restarted using the commands: ‘ntpd start’; ‘ntpd stop’ and ‘ntpd restart’. The NTP server daemon can be queried using the ‘ntpq –p’ command. The ntpq command queries the NTP server for synchronisation status and provides a list of servers with synchronisation information for each server.NTP Access ControlAccess to the NTP server can be restricted using the ‘restrict’ directive in the ntp.conf file. You can restrict all access to the NTP server with:restrict default ignoreTo only allow machines on your own network to synchronize with the server use:restrict 192.168.1.0 mask 255.255.255.0 nomodify notrapMultiple restrict directives can be specified in the ntp.conf file to restrict access to a specified range of computers.Authentication OptionsAuthentication allows a matching passwords to be specified by the NTP server and associated clients. NTP keys are stored in the ntp.keys file in the following format: Key-number M Key (The M stands for MD5 encryption), e.g.:1 M secret5 M RaBBit7 M TiMeLy10 M MYKEYIn the NTP configuration file ntp.conf, specify which of the keys specified above are trusted, i.e. are secure and you want to use. Any keys specified in the keys file but not trusted will not be used for authentication, e.g.:trustedkey 1 7 10The NTP server is now configured for authentication.Client Configuration for AuthenticationThe client needs to be configured with similar information as the server, however, you may use a subset of the keys specified on the server. A different subset of keys can be used on different clients, e.g.:Client A)1 M secret7 M TiMeLytrustedkey 1 7Client B)1 M secret5 M RaBBit7 M TiMeLy10 M MYKEYtrustedkey 7 10Essentially authentication is used by the client to authenticate that the time server is who he says he is, and that no rogue server intervenes. The key is encrypted and sent to the client by the server where it is unencrypted and checked against the client keys to ensure a match.

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Linux

If you’ve spent any lengthy amount of time on the Internet, you’ve probably heard of open source software but might not have fully understood what it is and why it even exists.

Most people purchase computers to run programs – whether it is to send email, browse the web, meet friends of girlfriends on msn messenger, do office work or just play solitaire.
People buy computers to use programs for their functionality not to run operating systems be in Microsoft Windows, the new Microsoft Vista product, the Mac Operations Systems or the various Linux Operating Systems – be they Ubuntu Linux, Mandiva, Knoppix or Debian.
At the heart of most computer users is functionality and usability. It is as simple as that. It is an interesting situation that the Microsoft Corporation controls the vast lion’s share of the computer operating system market. Indeed it even has a major share holding of the next player in line – Apple with the Macintosh OS (Operating System).
What are the issues?
1) Linux is not really free. Linux, in its various flavors or distros, is given free of charge, whether it is on a cd, DVD or downloaded. You can install the program on your own compute or various computers, at no charge to yourself whatsoever
This is in direct contrast to a commercial product such as Microsoft Windows or the new Microsoft Vista which you to purchase a boxed version or a valid license which comes with most computer systems purchased. This license which comes on most new computers as a matter of course could be referred to as the “Microsoft Computer Tax” and is not an option you can forego, to reduce the purchase of your new compute – whether or not you wish to use another operating system such as Linux.
Linux is given free of charge to install. This is not a shareware or time limited version of the product which requires a registration fee after a period of time.
If you require product support or training commercial organizations do exist which will charge you for support of that product or for training or both. Indeed it can be said that Microsoft itself charges for product support, Symantec the antivirus / security organization charges for basic support by product, subscription fees – sometimes automatic subscription fees and 900 phone number and charge card “Priority Support”.
Indeed you would not expect your local school or technical college to provide computer and compute software training free of charge.
2) Linux is complex and will force you to learn the Linux command line,
Not true simple as that. The various Linux distros all have GUI (Graphic User Interfaces) just like Microsoft Windows, Windows used to come as command line DOS. Windows users use pull down windows to operate the software. So can and do most Linux users
3) Compared to Windows, Installing Linux is Difficult
- The vast majority of computer users are computer neophytes and beginners.
These computer users purchase computers with the operations system Microsoft Windows or the Macintosh Operating System installed on their new computers. These people could not install the Windows Operating system and the device drivers necessary if their life depended on it. How the situation of a Linux is based computer any different.
It is only a matter of time until new computers come preinstalled with the Linux operating system. Imagine if Henry Ford had been told not to build new cars since there were few good roads available in America.
4) My Computer Hardware Just Works Under Windows
5) Again untrue in many cases and soon to be less of an issue as more and more computers will come preinstalled with a Linux operating system. Already Dell Computer (which was a Microsoft stalwart) is selling Linux based laptops. Interestingly the response to the Ubuntu Linux dell notebooks is quite positive, If you think Linux hardware compatibility is an issue try upgrading to the new Microsoft Vista from your previous Microsoft Windows product. You will find to your surprise that few if little of computer hardware are supported. You may have upgraded to the new Vista and found you have either no sound, good video or even internet connections via your network adapter device or wireless network adapter. And try undoing your upgrade to get back to your working windows version – it cannot be done.
Lastly you may say I run Windows since all of the programs I use are available only on the Windows operations system – since that is the dominant player in the market. You may well surmise that since Windows is the more than dominant player in the computer OS market that software developers write their product almost exclusively for the windows operations system and that market.
This is true. If you are using a specialized product for your job, industry, situation or preference you may well be locked in.
In the end most people buy and use computers for functionality and use. Most people use their computers for internet browsing, communication – whether it by email or messenger services (M.S.N., Yahoo, Skype, Eyeball Chat), downloading and burning music and in more than many cases for playing nothing more than computer games such as simple solitaire.
In these cases the functionality of Linux and its program base easily allows for this. Indeed many of the cutting edge programs and computer services come out of left field by computer software developers and enthusiasts whose preference of Computer Operating System is guess what – Linux in its various forms.

As I was sitting here, preparing to write this article, my mind wandered back to the day I accidentally wiped out a Windows installation with a Gutsy Gibbon CD. I thought I was in trouble. I had just knocked out my work documents, including various templates I made, along with scanner support, and my Adobe 8.0 suite.
It was at that moment I decided to make a go of it with Linux as my sole operating system. After nearly 2 years of tweaking, making mistakes, fixing those mistakes, and then making even more mistakes, I finally feel qualified to give you advice.
In light of this experience, I now present “11 Crucial Things An Ubuntu Newbie Should Know”.
Commands
1. ps -A: One of the reasons I hated Windows so much was the task manager. When a program would hang, you’d have to open task manager, tell it to kill the program, and wait 5 minutes for the system to kill the application, All the while, it would bog down the processor, hog memory, and be an overall nuisance. 50% of the time, you would have to restart the computer to get the process to clear.
Not so in Ubuntu/Linux. All you have to kill a program is open the terminal, and type “ps -A”. This will pull up a list of all the processes currently running, with the name of the program, along with a 4-5 digit number next to it. Then, type “kill -9 PN” (PN should be substituted with the actual Process Number), and hit enter. This will kill the app, no questions asked. It will not ask you any questions, or give you any excuses. That program is now dead, until the time you decide to resurrect it. This will not work with things like Apache, or other process daemons. If you’re not sure, just try to kill it. If it doesn’t die, then it is probably a daemon. You will have to find the actual documentation to stop the daemon.
Bonus tip: In Ubuntu (Gutsy and later), the command to stop Apache is: sudo /etc/init.d/apache2 stop To restart: sudo /etc/init.d/apache2 start
2. gksudo nautilus: Nautilus is the GUI-based file browser for Gnome, which is the default window manager for Ubuntu. If you are not used to the command line, this command will save you hours when it comes to file operations. Well, it will only save you hours for things that have to be done as root. Things like special system configuration, and other things where you need upgraded privileges will be much faster when you use this command.
Just open the terminal, type “gksudo nautilus”, enter your password, and magically you can do anything you want. For faster access, right click the Desktop, select “create launcher”, enter “gksudo nautilus” as the command. You can now click the shortcut on your Desktop, rather than opening the terminal and entering a command each time you need access to Nautilus.
3. dmesg: If you have managed to really mess something up, or are having trouble getting things to work, you may need someone with greater experience to take a look. Typing “dmesg” in your terminal window will call up all the messages from your system kernel. Copy and paste this into a text document, attach it to an email, and let a true expert get a look at what is going on with your hardware.
Upgrades:
4. Ubuntu’s package manager, Synaptic, is a GUI front-end for Aptitude. What you don’t know is that Synaptic is set to run in what could be called “safe-mode”. It will not go get the latest and greatest versions of the software you are running. It will get the last (often 6 months older) version of the software you want to run. You can upgrades faster by enabling optional software repositories.
To do this, open Synaptic (System > Administration > Synaptic Package Manager), then select Settings > Repositories. Once you are in the repositories window, select the “Updates” tab. The Ubuntu “security” and “recommended updates” repository have already been selected. To get the newer stuff, you need to check “backports” and “proposed” software. Apply, and reload. This should get most of your software up to date, along with the kernel.
5. The kernel: While having the latest and greatest stable kernel can improve system performance, it can also break little fixes you have made along the way. An example: I had gone through the painstaking process of editing some configuration files to get my webcam to work. The last kernel update overwrote the changes I had made, and in the process, disabled my webcam. This can get irritating, but eventually a kernel release might fix an issue on its own, so I guess it is an ok, if not completely lossless tradeoff.
6. Upgrading to the newest version of Ubuntu: Don’t do it right away. Always give a new version at least two months in regular use before you decide to upgrade. I have tried to upgrade for 3 releases now, in the first two weeks of availability for the upgrade. Each time, there has been a major failure, mostly in the area of graphics and sound. If your release is stable, there is no reason to upgrade right away, other than a few minor changes in speed and stability. You forfeit these if you upgrade on the first day of a new release. You have been warned.
Got Help?:
7. You can Google it: If you haven’t googled it, do not trounce into a forum and ask the question. People are nice, but they really can’t stand laziness. If you have searched, and can’t find it, it may be a more advanced question that really needs more expert analysis.
Here’s the search formula that reaps the best rewards for me: [manufacturer] [model] [problem] [ubuntu distribution]…(e.g. sony vaio webcam installation hardy). You can vary this formula a little bit, as sometimes it takes a few searches to get the hang of it. The one thing that you should not change is having your version of the distribution in the search. The reason is that fixes, and places where applications install can be different depending on the version you are using. This will ensure that you receive the best solution possible.
8. The Forums: Most of the time, Googling the problem will send you to the Ubuntu forums. Get a user name, log in, and be respectful. Be sure you try everything they tell you to before griping that it won’t work. The help and advice is free, and usually very helpful in nature.
9. Launchpad: This is a bug reporting service that Ubuntu users use to get bugs and various other problems fixed. You can reach the project at https://launchpad.net/ubuntu . Once you get there, click on report a bug, and follow the instructions. Be sure the problem has not been reported already, as they will ask. Provide as much information about the incident as possible. They will keep you posted on the progress as far as the problem being resolved, and assign a priority rating based on the severity of the problem. I’ve had to use it 2 or 3 times. Even the minor problems have been resolved in 2-3 weeks.
10. Don’t Be Afraid To Break It
This is the most important rule. This ain’t your Granny’s china. Stuff will break, you will be the one to break it. You will also be the one fixing it, along with your friend Google. Be patient, be persistent, and walk away for a bit if the solution just won’t come. Vindication will come, and when the fix is done properly, or you changed a variable that caused performance to increase, there will a mountaintop rush. Chances are, your significant other won’t care, but that won’t matter. Feel free to prance around in your boxers, and act like you just won the Nobel Prize.
11. Everything in Windows can be replaced with Open Source software: Really, it can. It takes a little time to find it, but when you do, a whole new world will open up. You’ll start to see how things work better than you expected. Things will play that would not on Windows, you’ll be able to open every attachment you ever wanted to. Productivity will increase, thereby giving you more time to make your system work faster, and work on your own open source program.
I can’t include everything I’ve learned over the past two years here. There are some other articles that I have written on software packages, and the pros and cons of each. Just google my name and iSnare to get a full list of what I have written on the subject. In conclusion, have fun with Ubuntu, share your knowledge with others, and fear God. Seriously.
That’s all the advice I have for you.

If you have any involvement with Information Technology, you’re probably already familiar with Linux as a server operating system. Indeed, for many applications Linux is an accepted and even preferred platform. Google has built and is expanding one of the world’s largest cluster of Linux servers to host its pervasive search engine system. Major hardware vendors, including IBM and Hewlett-Packard, sell servers preloaded with Linux and provide premium support for the operating system. Oracle is the largest commercial database running on Linux with more than 80% market share. Successful commercial applications like VMware ESX are built on Linux foundations. And many of the largest Internet hosting providers run on Linux.

On the other hand, if your computer experience is limited to your own home PC, you may never have even heard of Linux and may be wondering what all the fuss is about. If that’s the case, listen up because Linux may be coming to a desktop near you!What is Linux?

Simply put, Linux is a computer operating system like the Mac OS X or Microsoft Windows. The difference is that Linux is open source; anyone can view, modify, and redistribute the underlying code. Further, while OS X is designed to run only on Apple hardware, and while Windows runs primarily on x86 processors from Intel and AMD, there are many distributions or flavors of Linux, compiled to run on a wide array of hardware, everything from high-end corporate servers and mainframes, to home PC’s, to cell phones.

Linux began as a pet project of a Finnish university student, Linus Torvalds, in 1991 as an alternative to the server operating system Unix. He made it freely available to anyone who wished to modify it and it was quickly adopted and grew. Still, it remained primarily a server-based system. Few home users would have chosen its complex command-line interface over the comfortable and easy-to-use point-and-click GUI of the Macintosh or Windows.

However, Linux now also sports a graphical front-end and a plethora of user-friendly applications.Going GUI

Since Linux is all about choice, it’s not surprising that there are a number of graphical environments available. The two most popular that come preloaded on many distributions targeted for desktop or workstation use are Gnome and KDE. Both offer features home users have come to expect: menus, icons from which to launch applications and documents, desktop wallpaper, screen savers, trash icons, and the like.

Connecting to printers is a simple process of selecting the printer type from a menu and telling the system where to find it, either on a local port or a network queue. To print from most applications simply select File, Print. No surprises there.

Sharing folders is equally simple and relies upon standard protocols that interface well with Macintosh and Windows systems.

For security, you can create multiple user accounts; each user gets their own desktop they can customize as they wish. There’s also a built-in firewall to protect you from Internet intruders.

Of course, most people are more interested in the applications they can run, rather than the underlying operating system. Here, Linux is in no way deprived.Applications

For browsing the Internet, there’s Mozilla’s Firefox and Konqueror. For e-mail there’s Thunderbird and Evolution. The popular OpenOffice.org suite provides typical office functionality including word processing, spreadsheet, database, drawing, and presentations. The Gimp and Inkscape offer advanced graphics capabilities. And there’s a variety of utilities for burning CDs and DVDs, listening to music, watching videos, and chatting via services like AOL’s Instant Messenger.

This list is by no means complete. There are thousands of open source applications for Linux; you’d be hard-pressed not to find one that could do what you need. But there are also many commercial applications available.Drawbacks

If Linux offers so much of the same functionality as Windows, why isn’t it more widely used? Why do many home and corporate users reject it?

Microsoft Windows, while it has many faults, has become so widespread in its use as to be nearly ubiquitous. It has become the de facto standard by which other systems are measured. For those people already familiar with and comfortable with Windows, anything else is a step back, even if it is faster, more intuitive, more stable, and more secure.

Also, it must be admitted, there are still situations where you may need to venture into the cryptic world of the Linux command shell. For those used to living with a mouse in one hand, typing commands like awk and grep at a flashing cursor is unacceptable.

And, while there are enough applications to satisfy all but the most demanding of users, there are a few notable exceptions. Microsoft Office is not available on Linux, and likely never will be. Adobe Photoshop is also missing. In both cases, nearly all of the functionality these two giants provide is available in other applications, but for some die hards, that’s not good enough. While there are ways of running some Windows applications on Linux, they’re not usually as fast or as stable — or as easy to implement — as native Linux applications.

The situation is even dimmer for games. While the console market — PlayStation, Nintendo, and Xbox — is growing, the PC and Mac game market is shrinking. The commercial Linux game market is even smaller. Oh, there are plenty of games for Linux, but most are modest efforts, with few of the heavy hitters widely available on other platforms. Those that have been ported to Linux are not always fully supported — if they’re supported at all — by the original producer. For example, while you can purchase Quake 4 for Linux, don’t expect id Software to help you get it running, a task not for neophytes or those who shy away from the command line.Vendors

Despite any apparent drawbacks, some major vendors are actively promoting Linux on the desktop. Novell now offers the SUSE Linux Enterprise Desktop, while Red Hat offers Enterprise Linux WS, both targeted at corporations. Since users in this environment are likely to have a fixed set of applications without a heavy gaming need, Linux is often ideal. And a number of organizations are taking advantage of the potential savings offered by these open source options. Governments especially, under scrutiny for how they handle the public purse, are often quick to make the move. Among them are the cities of Largo, Florida, USA; Bristol, UK; and Bergen, Norway. They have each made their taxpayers happy with significant savings over the closed source, proprietary systems they used to use.Choices

If you’re a heavy gamer, then you’ll probably want to stick with Windows or a dedicated console. If your focus is advanced graphics and video editing, then Linux may be an option, if you’re willing to give up certain commercial applications. Otherwise, you’d be better off with a Macintosh. If you’re just surfing the Internet, sending e-mail, writing letters, and editing spreadsheets, then Linux and the open source software that comes with many distributions will do everything you need.

On the other hand, if you don’t want to ever see a command line or edit configuration files by hand, then Linux probably isn’t for you just yet. But it may be soon.

Jules Smith is the principal of LightningStrike Studios, a professional business and technical writing firm.
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