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Network Time Protocol – Explaining NTP Servers and Network Time Synchronisation

admin — Wed, 16 Dec 2009 00:29:26 +0000

NTP is almost as old as the Internet itself. It was devised and developed by Dr David Mills of the University of Delaware and has been in constant use and continually updated since 1985. NTP is an internet protocol designed to synchronise clocks on a computer network.

In a modern global economy time synchronisation is essential for carrying out time sensitive transactions such as booking an airline ticket to bidding on Ebay. If clocks were not synchronised to the same time you may find your airline seat sold after you had bought it and Ebay’s administrators would not be able to discover whose bid was the latest.

NTP can synchronise networks across the Internet or a Local/Wide Area Network (LAN/WAN) it synchronises time with reference to a reliable clock source. This source could be relative such as a computer’s internal clock or the time on a wrist-watch or absolute such as time from an atomic clock.

Most network administrators prefer to use an external absolute source, mainly because specialist NTP servers are available that can easily receive an atomic clock timing reference either through specialist radio transmissions (usually from national physics laboratories) or the GPS network.

A universal timescale called UTC (Coordinated Universal Time) has been developed allowing networks all around the world to be synchronized to the same timescale and supports such features as leap seconds – added to compensate for the slowing of the Earth’s rotation

NTP uses an algorithm (a complex sequence of instructions) to keep time by constantly checking the time source and matching it to the time on its clocks on the network and instructs each device to alter if it becomes out of synchronisation.

NTP uses timestamps to represent the current time of the day each. 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) 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 it’s reference clocks and itself.

The NTP program (daemon on UNIX, service on Windows) runs in the background. NTP receives exchanges time information by packets (a block of data) but refuses to believe the time it is told until several exchanges have taken place, each passing a set of tests or protocol specifications. Only if the replies from a server satisfy these tests does the NTP utilizes this information. It usually takes about five minutes (five good samples) until a NTP server is accepted as a timing source.

Microsoft, who has installed a version of NTP in their operating systems since Windows 2000, strongly recommends that a hardware source is used as a timing reference as Internet sources can’t be authenticated.

Authentication verifies that each timestamp has come from the intended time reference by analysing a set of agreed encryption keys that are sent along with the time information. NTP, using Message Digest encryption (MD5) to un-encrypt the key, analyses it and confirms whether it has come from the trusted time source by verifying it against a set of trusted keys.

The best solution is to use a specialist NTP server and receive an authoritative time reference via either the GPS network or radio transmissions (known as MSF in the UK or WWVB in the US).

NTP servers judge the distance of each network device from a timing source and organises them into Strata. These Stratum levels exist to prevent cycles and guarantee accuracy. Stratum 0 are devices such as reference clocks connected directly to a computer. Stratum 1 are computers attached to stratum 0 devices, while Stratum 2 are computers further out.

NTP is free to download via NTP.org and is continually supported and updated. The current version is v 4. A simplified version of NTP (SNTP) exists has less functions and is used in some devices and applications (and also included in older versions of Windows) where high accuracy timing is not as important.

By: Richard N Williams

Wireless Network Security: How to Use Kismet

admin — Sun, 13 Dec 2009 08:55:54 +0000

Kismet is a wireless network detector / sniffer which can give you a vast amount of information about wireless networks. Wireless network security flaws are well documented but often very hard for the common person to understand. I will be showing you how to use kismet with out even having to install Linux, or compile kismet.

First you need to proceed to remote-exploit.org and download and burn their Auditor CD. (IF you don’t know how to burn an ISO image, go to Google). This version of Linux doesn’t install or modify your hard drive; it will boot from the CD and use a Ram Drive (On your Memory).

Auditor is not only a great tool for testing wireless network security with kismet but it also has many other computer security tools on it as well.

Client Window

Next, to start Kismet proceed to the Linux version of the start menu, and press Auditor.
Now proceed to the wireless /scanning/kismet tools/kismet.

Once you click on Kismet it will ask you for a default location to place the Kismet log files for analyzing later, just press the desktop or temp file.

Now I will show you how to use Kismet. When kismet initially opens you will see a greenish box with numbers and network names (If any are near you) clicking away don’t be overwhelmed. (Also I can’t show you how to use kismet if you don’t have the correct wireless adapter, get an ORINICO Gold Classic Card off EBAY.) The Orninco gold classic card will be automaticly detected by auditor linux.

The Kismet columns will show the wireless networks SSID (Name), Type of device (Access point, gateway) Encryption or no Encryption, an IP range and number of packets. Kismet will pick up hidden networks with SSID broadcast Disabled also, Netstumbler will not.

Now Press H, to bring up the Help Menu. This will give the nuts and bolts on how to use kismet. If you tab down to the network you are auditing and press “C”, Kismet will show you all the computers that are using that wireless access point / gateway. This Kismet screen will show you the clients MAC address, Manufacture of Wireless Adapter, IP address range and traffic.

Kismet: Help Menue

Now to get out of that screen press “Q”. Tab Down on the Main Kismet Screen to another SSID and press “I”. This Kismet window will show detailed information about the wireless network. The Kismet detail screen will show the type of network (Infrastructrure / Adhoc), signal strength, channel, encryption type, and much more.

Kismet will also give you sound alerts when new wireless networks are discovered or security alerts or suspicious clients are in range. Suspicious clients would be people like you who are using Kismet or Networkstumbler. Unlike you these could be Wardrivers looking for venerable networks to hack into.

Kismet Alert Page

You can prevent War drivers from discovering your wireless network by performing a proper site survey which will help limit signal bleed off to unneeded areas. You should write down the suspicious MAC address and keep an eye on your access logs. If the War Drivers are really stupid just look out your window and look for cars with weird antennas.HA HA HA.

Kismet is more than just a tool to discover wireless networks; it can be used in conjunction with other tools to crack WEP/WPA. Many websites will claim that WEP can be cracked in less that five minutes. This is only half the truth because it could take many hours,days,months to gather enough packets to crack. Good luck and have fun learning the more advanced applications of kismet.

By: Eric Meyer

5 Work At Home Computer Based Businesses

admin — Fri, 20 Nov 2009 07:17:08 +0000

With the internet continuously expanding, every day there are more and more work at home computer based businesses to choose from. There are several advantages to being able to work from your home and it allows you to do what you have always wanted to do. Here are 5 work at home computer based businesses to consider.

1. Affiliate marketing

Affiliate marketing has great potential because there are so many businesses and companies online that offer affiliate programs. What affiliate marketing entails is you selling someone else’s products. For every sale that you make, you earn a certain commission. Because there are so many programs to choose from, it is vital that you select one with a high commission rate so that your efforts are properly rewarded.

2. eBay

eBay is a work at home business that has just recently taken off. There are a number of ways you can turn eBay into an actual business. First, you would be surprised at how much of your “junk” is treasure to someone else. Gathering things from your house can make you a great deal of money. The main way people turn eBay into an actual business is by purchasing a hot item that may run out, such as PS3 or XBOX 360, and turning around and selling it for more than you purchased it for.

3. Article writing

There is constant demand on the internet for fresh and enticing content. Regardless of what business or company you may have, content is something every site needs. The problem is many people cannot write sufficiently, which leads to you. As long as you can properly research topics and write sufficiently, you can make a great business out of writing articles.

4. Freelance

The internet is great for freelance work because there are so many opportunities to choose from. Whether you want to write articles for people, be a graphic designer, or be an editor, there are a number of professions to choose from. And you will always have work because the internet is growing at an incredible rate.

5. Start a web site

The ultimate work at home computer based business is creating your own web site. To do this successfully, it is best to start something with high demand but minimal competition. If you start a web site within an industry that has thousands of competitors, it is going to be extremely difficult to have success. Starting your own web site also allows you to get into article writing, affiliate marketing, and many more business ventures.

The internet is full of opportunities for entrepreneurs looking to work for themselves. The five work at home computer based businesses listed here have great potential and can ultimately turn your life around for the better.

By: Damon Jennings

Computer Home Jobs – Recession Proof

admin — Fri, 09 Oct 2009 04:59:54 +0000

Has the recession changed your life? Are you looking for a way to make money from home that will be successful even during tough times? You do have options. With computer home jobs you can bring in extra cash regardless of the condition the economy is in. There are recession proof opportunities out there if you know where to find them. The Internet is still growing, despite the global downswing and people are making money selling goods Online. Let’s take a look at Internet Marketing and how you can use it to your advantage in times such as these.

Is Internet Marketing The Best Option? I have spent a lot of time asking this very same question. Having spent countless hours Online researching computer home jobs that are recession proof, I came to the conclusion that Internet marketing is the most viable option out there. I am sure you have looked into surveys, Ebay, and numerous wealth building programs. Internet Marketing is the one option that can provide a steady income once the learning curve is mastered. There are ways you can promote a product that require very little out of pocket expenses. Also working from home can be a very motivating force to succeed.

Why Is Internet Marketing Recession Proof? Mainly due to the fact that people are spending money. We all have to have food, transportation, health related products and services, clothing, etc…etc. With this in mind more and more folks are turning to the Internet to make these types of purchases. People enjoy the convenience as well as the price savings they get though the web. The reality is money is being spent, it just has shifted more from spending on what someone wants to what someone needs. In deciding that computer home jobs is right for you, you are in position to make commissions on customers who purchase Online.

What Are Some Of The Benefits Of This Business?
#1 First and foremost with computer home jobs you will be your own boss. Freedom in planning your schedule.
#2 The thought of being able to work from anywhere there is a Internet connection is very appealing to a lot of people.
#3 The sky is the limit as far as income potential. There are those who make $50 a week to those who bring in over $10,000 per week. It all depends on the effort put into it.
#4 This can be learned in a few short months. The cost is reasonable at around $35 a month for the education and tools needed to get you going.
#5 And of course this is recession proof.

How Do You Get Started? As I stated before, Internet Marketing is a legit Online business and has the potential for a wonderful income. To get started look into what it takes to educate yourself in this field. There are sites out there that will help you every step of the way. Go into this knowing you can succeed. From my experience the only ones that fail are those who don’t follow through. When it comes to computer home jobs that are recession proof, Internet Marketing is tough to beat.

By: Tom Borgstrom