Logic or Algorithm


In mathematics and computer science, an algorithm (i/ˈælɡərɪðəm/ al-gə-ri-dhəm) is a step-by-step procedure for calculations. Algorithms are used for calculation, data processing, and automated reasoning.


Logic (from the Ancient Greek: λογική, logike)[1] has two meanings: first, it describes the use of valid reasoning in some activity; second, it names thenormative study of reasoning or a branch thereof.[2][3] In the latter sense, it features most prominently in the subjects of philosophy, mathematics, andcomputer science.


How to enable IP Forwarding

By default any modern Linux distributions will have IP Forwarding disabled. This is normally a good idea, as most peoples will not need IP Forwarding, but if we are setting up a Linux router/gateway or maybe a VPN server (pptp or ipsec) or just a plain dial-in server then we will need to enable forwarding. This can be done in several ways that I will present bellow.

Check if IP Forwarding is enabled
We have to query the sysctl kernel value net.ipv4.ip_forward to see if forwarding is enabled or not:

Using sysctl:

sysctl net.ipv4.ip_forward
net.ipv4.ip_forward = 0

or just checking out the value in the /proc system:

cat /proc/sys/net/ipv4/ip_forward

As we can see in both the above examples this was disabled (as show by the value 0).

Enable IP Forwarding on the fly
As with any sysctl kernel parameters we can change the value of net.ipv4.ip_forward on the fly (without rebooting the system):

sysctl -w net.ipv4.ip_forward=1


echo 1 > /proc/sys/net/ipv4/ip_forward

the setting is changed instantly; the result will not be preserved after rebooting the system.

Permanent setting using /etc/sysctl.conf
If we want to make this configuration permanent the best way to do it is using the file /etc/sysctl.conf where we can add a line containing net.ipv4.ip_forward = 1

net.ipv4.ip_forward = 1

if you already have an entry net.ipv4.ip_forward with the value 0 you can change that 1.

To enable the changes made in sysctl.conf you will need to run the command:

sysctl -p /etc/sysctl.conf

On RedHat based systems this is also enabled when restarting the network service:

service network restart

Read more: http://linuxpoison.blogspot.com/2008/01/how-to-enable-ip-forwarding.html#ixzz2uRwXx8Kd

Hacker ងាកៗ​អុក​ឡុក! ចឹង​Email មួយ​ណា​​ទើប​មាន​ សុវត្ថិភាព​​ខ្ពស់​ទុក​ចិត្ត​បាន?

បើ​និយាយ​ពី​រឿង​ប្រើ​អ៊ីមែល​វិញ ​ទាំង​យើង​ទាំង​គេ ចេះ​តែ​ប្រើ​ផ្ញើ​ឯកសារ រូបភាព​លិច​កើត​ តែ​មិន​ដឹង​អី​សោះ​ពី​រឿង​សុវត្ថិភាព ឬ​រឿង​គេ​Hack ​លួច​ទិន្នន័យ​នោះ​ទេ។ មាន​អ្នក​ខ្លះ​មិន​ទាំង​ដឹង​ត្រូវ​ប្រើ​​អ៊ីមែល​អ្វី​ទៀត គឺ​ចេះ​តែ​ចុះ​ឈ្មោះ​តាម​គេ​ឯង គេ​ថា​ Yahoo គឺ Yahoo ដល់​គេ​ថា Gmail គឺ Gmail។ ចុះ​ប្រិយមិត្ត​ជា​អ្នក​ប្រើប្រាស់ មាន​ដឹង​ទេ​ថា​អ៊ីមែល​មួយ​ណា​មាន​សុវត្ថិភាព​ខ្ពស់​អាច​ការពារ​មិន​ឲ្យ​គេ​Hack ​ចូល​បាន?

សេវា​អ៊ីមែល​ដែល​គេ​និយម​ប្រើប្រាស់​ច្រើន​ជាង​គេ​ក្នុង​ពិភពលោក​មាន ៣ ធំៗ៖ Hotmail, YahooMail និង Gmail។ ចុះ​មួយ​ណា​មាន​សុវត្ថិភាព និង​ងាយ​ស្រួល​ជាង​គេ​?

អាន​អត្ថបទ៖ អ្នក​ប្រើប្រាស់ Yahoo Mail គួរ​ប្ដូរ​លេខ​សម្ងាត់​ភ្លាមៗ!

– ព័ត៌មាន​ទូទៅ

១. Hotmail: វា​ជា​សេវា​អ៊ីមែល​របស់​ក្រុមហ៊ុន Microsoft។ Hotmail មាន​អ្នក​ប្រើប្រាស់​ជាង ៣៦០ លាន​នាក់​ឯណោះ​នៅ​ទូទាំង​ពិភពលោក។

២. YahooMail: វា​ជា​សេវា​អ៊ីមែល​របស់​ក្រុមហ៊ុន Yahoo។ Yahoo មាន​អ្នក​ប្រើប្រាស់​ប្រមាណ​ជា ២៧៣ លាន​នាក់​នៅ​ទូទាំង​ពិភពលោក ។

៣. Gmail: វា​ជា​សេវា​អ៊ីមែល​របស់​ក្រុមហ៊ុន​យក្ស Google ។ Gmail មាន​អ្នក​ប្រើប្រាស់​ប្រមាណ​ជា ១៩៣,៣ លាន​នាក់​នៅ​ទូទាំង​ពិភពលោក។


ក្នុង​ចំណោម​សេវា​​អ៊ីមែល​​ធំៗ​ទាំង​៣ Hotmail ទទួល​បាន​ចំណាត់​ថ្នាក់​ផ្កាយ ៤,៥ Gmail ផ្កាយ ៤ និង YahooMail ផ្កាយ ៣ ក្នុង​ចំណោម​ផ្កាយ​សរុប​ទាំង ៥។ ផ្អែក​លើ​ទិន្នន័យ​ទូទាំង​ពិភពលោក គេ​និយម​ប្រើប្រាស់ Hotmail ជាង​គេ ខណៈ​ដែល​នៅ​កម្ពុជា​យើង​វិញ និយម​ប្រើប្រាស់ Gmail ច្រើន​ឡើងៗ។

បច្ចុប្បន្ន សេវា​​អ៊ីមែល​​ទាំង​៣ នេះ​មាន​សុវត្ថិភាព​ខ្ពស់ ដោយ​មាន​លេខ​សម្ងាត់​ដល់​ទៅ ២ តង់​ឯណោះ។ នៅ​ពេល log in ចូល​ដំបូង វា​នឹង​ផ្ញើ​សារ​មក​កាន់​ទូរសព្ទ​ដៃ​របស់​អ្នក​ប្រើប្រាស់​ប្រាប់​ពី​លេខ​កូដ ដែល​លេខ​កូដ​នោះ​សម្រាប់​យក​ទៅ​បំពេញ​ក្នុង​ដំណាក់កាល log in លើក​ទី​២។ ប្រព័ន្ធ​សុវត្ថិភាព​ពីរ​តង់​នេះ គឺ​ដូច​គ្នា​បេះបិទ​នឹង​ប្រព័ន្ធ​សុវត្ថិភាព​របស់​ធនាគារ (iBanking) និង​ធានា​បាន​នូវ​សុវត្ថិភាព​ខ្ពស់។

ប៉ុន្តែ អ្នក​ប្រើប្រាស់​ភាគ​ច្រើន​គិត​ថា ការ​ផ្ញើ​សារ​មក​ទូរសព្ទ​ដៃ​ពេល log in ចូល​ម្ដងៗ ជា​ការ​រំខាន។ អីចឹង ពួកគេ​មិន​បាន​បង្កើត​លេខ​សម្ងាត់​តង់​ទី​២ នោះ​ឡើយ។

កន្លង​មក គណនី​​អ៊ីមែល​​របស់ Hotmail និង Gmail មិន​ដែល​លេច​ឮ​ត្រូវ​គេ​ហែក​លួច​ទិន្នន័យ​បាន​នោះ​ឡើយ គឺ​មាន​តែ​ YahooMail មួយ​តែ​ប៉ុណ្ណោះ​ដែល​មាន​ hackers ធ្លាប់​លួច​ហែក​បាន។

ចុះ​ប្រិយមិត្ត​វិញ ចូលចិត្ត​ប្រើ​អ៊ីម៉ែល​មួយ​ណា​ជាង​គេ?

ដោយ៖ សុផាត
ប្រភព៖ foxbusiness translated by Sabay

Google Plans to Bring Ultra-Fast Internet to More Than 30 Cities

PHOTO: Boxes of equipment needed to install Google Fiber broadband network sit on a couch at the home of customer Becki Sherwood in Kansas City, Kansas, U.S., Nov. 27, 2012.

Boxes of equipment needed to install Google Fiber broadband network sit on a couch at the home of customer Becki Sherwood in Kansas City, Kansas, U.S., Nov. 27, 2012.
Julie Denesha/Bloomberg/Getty Images

Google Fiber is devoted to making the Internet a hundred times faster than it is for most of the United States. On Feb. 19, the company announced plans to bring the Google upgrade to several cities spread across nine different metropolitan areas, including Atlanta and Nashville.

"People are hungrier than ever for faster Internet, and as a result, cities across America are making speed a priority," Milo Medin, the VP of Google Access Services, said in a company blog. "Now that we’ve learned a lot from our Google Fiber projects in Kansas City, Austin and Provo, we want to help build more ultra-fast networks."

But those eager to ditch their current service providers for Google may want to wait before pulling the trigger. Google will work with the cities to evaluate exactly how it would install its fiber-optic network. "While we do want to bring Fiber to every one of these cities, it might not work out for everyone," Medin said.

Google Fiber Expands TV, Internet to Austin, Texas

Teresa Mastrangelo, the principal analyst at Broadbandtrends, said the length of the evaluation phase varies from city to city. "In Kansas City, it took about six months," she told ABC News. "Austin is taking longer, since they announced in April 2013 and [the city] hasn’t asked the community yet to start pre-registering."

The mere mention of Google Fiber may be enough to get other Internet service providers in the area to step it up.

"In Austin, after Google said they were deploying Google Fiber, AT&T said that they would be putting in a fiber network too," said Mastrangelo. "Google is definitely trying to stir up some activity to get operators … to take a deeper look at what they can do with a broadband network."

Regardless of what it does for the broadband industry, Mastrangelo sees it as a win-win situation for the city. "Kansas City is very happy with Google Fiber," she said. "It’s great for the consumer, no doubt."

The following metropolitan areas are Google Fiber’s latest candidates.

  • Phoenix, Ariz.
  • San Jose, Calif.
  • Atlanta, Ga.
  • Charlotte, N.C.
  • Raleigh-Durham, N.C.
  • Portland, Ore.
  • Nashville, Tenn.
  • San Antonio, Texas
  • Salt Lake City, Utah

Set IP Configuration via Command in Windows

Changing Your IP Address

Changing your IP information requires two commands, one for your IP address, subnet mask and default gateway and another for your DNS settings. In order to change your IP address we use the netsh command, the exact command you want to use is the following:

netsh interface ip set address name=”Local Area Connection” static

This assumes the following:

  • The name of the interface you want to change the IP address for is Local Area Network
  • You want to statically assign an IP address of
  • You want to set a subnet mask of
  • You want to set a default gateway of

Armed with this information you should obviously switch the settings out for some that are suited to your network. You might, however, be wondering how you can go from using an already set static IP address to getting an address from DHCP. In this case the command you are looking for is:

netsh interface ip set address name=”Local Area Connection” source=dhcp

Changing Your DNS Settings

As far as DNS goes you only have two settings to set, a primary DNS server as well as a secondary one. The command to set them is almost identical, to set your primary DNS server you will want to use:

netsh interface ip set dns name=”Local Area Connection” static

This again assumes a few things:

  • The name of the interface you want to change the primary DNS setting for is Local Area Network
  • The IP address of the DNS Server is

To change the IP address of the secondary DNS server you will need to specify the index parameter:

netsh interface ip add dns name=”Local Area Connection” index=2

or to remove use:

netsh interface ip del dns name=”Local Area Connection” index=2

Sony unveils the waterproof Z2 phone and tablet, and low-cost M2 phone

BARCELONA, Spain — Splish, splash, Sony’s taking a bath with a raft of waterproof gadgets. The Sony Xperia Z2 smartphone and Z2 tablet can take a dip without making your day a washout — and they’re joined by a World Cup version of the Sony SmartBand and Core gadget.

Fancy splashing out on a smartphone that doesn’t care if it gets splashed? The Xperia Z2 is Sony’s new 5.2-inch flagship. Make a splash with our hands-on first take preview here.

If you want to get some of the same features but without spending so much, check out the Xperia M2. Get our early impressions with our hands-on first take here.

The Z2 tablet is a 10.1-inch slate that packs the latest Android KitKat software into a slim, waterproof casing. Dive into our hands-on preview here.

Sony also revealed more details about the SmartBand, its new wristband that straps the Core fitness gadget to your arm to track your activity. It’s on sale in March in black, with a yellow and green version celebrating the 2014 World Cup taking place in Brazil this summer.

For more of the coolest phones, tablets and mobile gadgets of 2014, check out our in-depth coverage of Mobile World Congress here — you won’t regret it.

Correction: This story initially stated that the Xperia M2 is waterproof. Sony’s other two products announced at Mobile World Congress, the Sony Xperia Z2 and Z2 tablet, are waterproof, but the Xperia M2 is not.

Facebook to discontinue email service


Facebook will soon be discontinuing its troubled @facebook.com e-mail service and has already started notifying some users of the impending change. Existing users will soon have their @facebook.com messages forwarded to the primary e-mail address on file while those without a primary address simply won’t have messages forwarded to them.

Originally launched in late 2010, the social network hoped the e-mail service would eventually put established providers like AOL, Google, Microsoft and Yahoo out to pasture. Facebook argued that traditional services were simply too slow and too cumbersome but their vision simply never came to pass.

Facebook said they are making the change because most people haven’t been using their Facebook e-mail address and they want to make it easier to view all messages in one place. Additionally, the change will allow them to focus on improving their mobile messaging experience.

It’s worth noting that message forwarding is enabled by default. Unfortunately, this means that someone can now reach your primary inbox simply by sending a message to your Facebook e-mail account. Such addresses are only visible to friends but as The Verge points out, it’s not difficult to figure out another person’s address by plugging in their profile page URL before the @ symbol.

The good news is that forwarding can be disabled completely, a move that will effectively shut down the service once and for all.

Source : http://www.techspot.com/news/55793-facebook-to-discontinue-facebookcom-e-mail-service.html​​

LG unveils the F90 and F70 midrange handsets

F 90 - F 70

LG unveiled two new midrange offerings earlier today amidst a flurry of announcements from several companies. The Korean manufacturer has launched the F70 and F90 handsets which will join the company’s recently launched G2 mini handset in the midrange setup.

The LG F70 sports a 4.5 inch 480 x 800 resolution display, a 1.2 GHz quad core Snapdragon 400 chipset, 512MB of RAM, 4GB of internal storage (expandable), Android 4.4 KitKat and a 2,440 mAh battery.

The LG F90 sports a slightly bigger 4.7 inch display with a qHD (960 x 540) resolution and shares the processor, storage and the RAM from the F70. The F90 also comes with Android 4.4 KitKat out of the box and features a slightly bigger 3,000 mAh battery.

What’s special about these two devices is the fact that they both come with 4G LTE support, thus justifying the use of a relatively large battery. These handsets are expected to go on sale in the coming months in LG’s key target regions like Asia, Europe, Central America and other regions. Pricing details haven’t been disclosed as of yet.

Source: Fone Arena

Read more at http://thedroidguy.com/2014/02/lg-unveils-the-f90-and-f70-midrange-handsets/#C0Gb4ivFcsXLT2Q5.99

The mystery behind computer speed

Apple's Mac Pro, which can be configured to house up to a 12-core processor.

Apple’s Mac Pro, which can be configured to house up to a 12-core processor. Photo: Bloomberg

It used to be that megahertz and gigahertz were what sold computers. But clock speeds long ago stabilised around a few gigahertz and the new attraction is the number of cores.

We used to be told that a faster clock means a faster computer. Now we’re told the more cores the better since it lets the computer do more things at once.

Well, yes and no. Just as the earlier obsession with clock speed oversimplified things – lots of factors affect the speed of a computer, and the clock is just one potential bottleneck – multiple cores are not a magic bullet.

Go slow zone: Lots of factors affect how fast your computer operates.

Go slow zone: Lots of factors affect how fast your computer operates. Photo: iStock

A computer program is just a sequence of instructions for a processor to follow.


In the early days a computer had only one processor which is why the processor’s clock speed was seen as so important.

The faster the clock ticked the more instructions would be run per second.

But there are good reasons to build computers with more than one processor, each executing its own sequence of instructions but sharing all the other parts of the system, such as memory and input-output hardware. Each processor can execute a different program, or alternatively the processors can split the work of one program among them "in parallel" to get it done in less time.

Because of the added cost of duplicating the processor and supporting hardware, multiple processors came rather late to personal computing.

It only really took off once manufacturers started putting more than one core on the same chip.

Each core is effectively a separate processor.

It might seem that you need multiple processors to support multitasking, but that isn’t true.

Computers can multitask fine with just one processor. The true power of multiple processors is dividing up complex tasks into lots of similar sub-tasks which are then handled in parallel.

3D graphics, for example, is particularly amenable to this approach. The 3D model in the computer can be divided up into polygons that are treated independently.

The pixels that make up the 2D image can also be divided up for independent treatment. Modern graphics hardware contains hundreds or thousands of specialised parallel processors to take advantage of this. There are lots of more specialised applications of parallel processing, too, such as scientific simulations, software development and weather forecasting.

But a task can only be parallelised if it can be cleanly subdivided.

Any interaction between the sub-tasks reduces the effectiveness of parallel processing as they pause to co-ordinate their activities.

As an extreme example, if one sub-task depends on the results of another then the first will end up waiting for the second and the benefits of parallelism will be lost entirely.

For those programs that can benefit the parallel approach has to be explicitly added by the programmers.

The hardware alone won’t help you if software doesn’t take advantage of it.

Most things we mere mortals do with our computers do not benefit much from multiple processors – or cores.

One processor is always enough, two makes things run a bit more smoothly during bursts of activity, but the returns diminish rapidly thereafter.

Performance doesn’t always improve just because you pile on the processors.

Read more: http://www.smh.com.au/digital-life/computers/the-mystery-behind-computer-speed-20140218-32xkk.html#ixzz2uINM6mOp

Samsung reveals Galaxy S5 with fingerprint scanner, heart-rate monitor

The back of a gold Galaxy S5 smartphone.Click for more photos

Samsung at Mobile World Congress

The back of a gold Galaxy S5 smartphone. Photo: Bloomberg

  • The back of a gold Galaxy S5 smartphone.
  • The line-up: (From left) the Galaxy S5 smartphone, Gear 2 smart watch and Gear Fit fitness band.
  • Samsung's Galaxy S5 flagship smartphone.
  • Samsung's JK Shin sports the Gear Fit fitness band.
  • Samsung's Galaxy S5 flagship smartphones.
  • The back of a blue Galaxy S5.
  • The Samsung Gear Fit fitness band, left, and Gear 2 smart watch.
  • The Samsung Galaxy S5 smartphone.
  • Samsung's Galaxy S5 smartphone.
  • Samsung's Gear 2 smart watch.
  • Samsung's Galaxy S5 smartphones.
  • Samsung's Galaxy S5 smartphone, left, and Gear 2 smart watch.

Samsung has unveiled its answer to Apple’s flagship iPhone 5s in a move set to ramp up the rivalry between the world’s two biggest phone makers.

Samsung debuted the Galaxy S5 at the Mobile World Congress in Barcelona on Monday evening (Tuesday morning AEDT).

Samsung's Gear Fit fitness band.

Samsung’s Gear Fit fitness band. Photo: Reuters

The phone freshens up the flagship Galaxy line, which has been Samsung’s chief weapon in the battle for global smartphone supremacy. It begins shipping worldwide, including to Australia, on April 11.


With a 5.1-inch screen, the S5 is slightly larger than the phone it updates – the one-year-old Galaxy S4.

Samsung has also given it a better camera and built a heart-rate monitor into the flash on the rear. The smartphone is also water- and dust-proof, designed to withstand 30 minutes submerged in 1 metre of water.

But the biggest addition is a fingerprint scanner which, like the one on the iPhone 5s, is built into the home button.

Users can teach the phone to recognise three different fingerprints. They can then swipe their finger across the home button to unlock the phone rather than having to key in a code or swipe a pattern.

And in a considerable expansion of the technology, Samsung has partnered with online payment provider PayPal to enable a range of online purchases to be verified with the swipe of a finger.

The fingerprint scanner on the iPhone 5s, by contrast, can only be used to unlock the phone and to verify purchases through Apple’s own App Store.

The camera shoots in 16 megapixels – an increase of three megapixels on the S4.

Samsung has also sped up the autofocus from about 1 second to 0.3 seconds, allowing for better action shots, while another feature allows for better photos in low light.

A more powerful battery means the phone will last about 20 per cent longer than the S4 before needing a recharge. The company claims the device has 21 hours of talk time, though this decreases when using the phone for other things such as browsing the web and watching videos.

For people who need even more battery life, the S5 has an optional ultra power-saving mode which turns the screen black and white and cuts down the phone’s functions to the bare essentials, such as phone calls and texts.

The smartphone will come in black, white, blue, and gold, the company said, with either 16 or 32 gigabytes (GB) of on-board storage.

The S5 features a full-HD 1920 by 1080 pixel screen and is powered by a 2.5-gigahertz quad-core processor and 2 GB of RAM.

"The Galaxy S5 has great features and will probably sell well due to massive marketing support," said Forrester Research analyst Thomas Husson.

"But is the total product experience it offers differentiated enough to continue the sales success story? Is it enough to bet on fitness and fingerprint sensors to beat Apple – rooting the experience in people’s daily lives? I don’t think so."

Samsung has not said how much the new flagship device will cost. Optus and Virgin Mobile have confirmed they will offer the S5.

Fitness band

The company also unveiled its first attempt at a dedicated fitness-tracking wristband.

Called the Gear Fit, it has a colourful curved 1.84-inch AMOLED touchscreen and weighs about 30 grams.

It contains a pedometer, heart-rate monitor, timer and stopwatch and can also notify users when their phone receives a text, call or email.

It connects to your smartphone via Bluetooth provides notifications from phone apps such as Twitter, and can serve as music controller.

The device is water- and dust-proof, the company said, and its battery will last for three to five days.

The Gear Fit has a core focus on health and fitness, as opposed to its larger siblings, the Gear 2 and Gear 2 Neo smart watches, which were unveiled by Samsung on the eve of the trade show.

There is no word on when the Gear Fit will come to Australia or how much it will cost.

What do you think of Samsung’s Galaxy S5? Let us know in the comments.

The writer travelled to Barcelona as a guest of Samsung.

AAP, Fairfax Media

Read more: http://www.smh.com.au/digital-life/mobiles/samsung-reveals-galaxy-s5-with-fingerprint-scanner-heartrate-monitor-20140225-33dnj.html#ixzz2uIMipqzz