Oct 152017

In my previous post, I had detailed about how to lock the biometric access for your Aadhaar data. The process is beneficial to ensure that no one misuses your Aadhaar. But it is quite a cumbersome process to enable/disable the biometric access each time when try to authenticate using biometrics. So UIDAI has provided the facility to lock your biometric access via their mAadhaar mobile application. Here’s how to use it.

Note that you can use mAadhaar for identification and authentication at various services. You need not carry the physical Aadhaar card copy with you.

Installing the App

As always, you should download and install the app through official channels. For android the link is here. The app is developed by UIDAI and currently supports biometric lock/temporary unlock service/Permanently Disable serivce. The UIDAI is also in process of setting up the Teomporary OTP(TOPT) service which will not require you to request for any OTP via sms. The TOPT keeps on changing every 30 seconds.

The app is not available on iOS so iPhone users will have to wait a while till UIDAI releases it.

Install the app using the the link above. Launch the app from your app drawer.

The first thing it will ask you to do is to create a password for logging in to the app. Once you create a strong password, the app will ask you to create a profile by linking your Aadhaar. You can either enter your Aadhaar number in the blank fields of scan the QR code on the Aadhaar card using the Scan QR Code facility. Once you feed in the Aadhaar number, you will get a SMS with OTP to verify your entries. The OTP will be auto entered in the relevant field. Click on “Verify” button to verify your entry.


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Once you verify the OTP, your mAadhaar will be available for you to view. But to access the details, each time you will need to enter the password whenever you do any critical action in the app. For example, while you try to check your Aadhaar details or while changing biometric lock status, the app will ask you for password.



How to Lock Biometric Access

Once you have setup your profile, to lock biometric access, click on the the three vertical dots on the right top corner. A menu will drop down. Click on “Biometric Settings”. The app will go in to the biometric settings screen. Here, select the “Enable Biometric Lock” option. After that, click on the check mark on the top right hand corner. It will prompt that you may still be able to use biometric authentication for few hours. Once you click OK, the app will go to the OTP verification screen will automatically read the OTP if sim in the phone is linked to your Aadhaar. If it doesn’t read automatically, you can enter it from the SMS that you receive. Then click OK. The app will take you back to home screen which will now show on the bottom that the biometric authentication is locked.

Follow the slide show below.

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How to Temporarily Disable Biometric Lock

At times, you may need to use biometric mode of Aadhaar authentication and during such time you will have to unlock biometric access.

For this, login to your profile once again. At he bottom of your profile, you can see the message stating “Biometrics Locked(Click to Unlock)”. Click on the message. The app will ask you to enter the password. Once the correct password is entered, the Biometric Authentication Access will be unlocked for 10 minutes. At the bottom of your profile page, you see a countdown timer showing you the time remaining. The Biometric Authentication access will automatically get locked upon expiry of this time.

Refer below slideshow.

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How to Permanently Disable Biometric Lock

If you want to disable the Biometric Access Lock permanently, follow these steps. Click on the three vertical dots on the right hand top corner and you will go to the Biometric Lock settings. Un-check the “Enable Biometric Lock” option and click on the tick mark on the top right corner. The app will prompt you again that you still may not be able to access Biometric Access feature for few hours. When you click OK, the app will automatically read the SMS received from UIDAI. Click on OK and this will disable Biometric Lock permanently.

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It is advisable to keep your Biometric Authentication access, always locked since mAadhaar has made it easy to unlock it quickly whenever needed.

Oct 082017

One of my previous posts introduced you to NPCI and the products and services offered by them. Today we concentrate more on UPI BHIM mobile app and see how we can use it for our daily transactions. The transactions can be money transfer from one party to another or a payment at merchant point of sale terminals.

The older methods

For money transfer, we have been using the NEFT/RTGS and the IMPS services for quite some time. These services require that the remitter knows the beneficiary details. It is quite difficult to remember these details. The remitter has to feed a 15-16 digit account number, IFSC code, Bank Branch details and the correct name of the account holder. Some banks also have set a period of time before which the beneficiary is not activated. So in case of emergency, immediate transfer to a new beneficiary is not possible.

For online payments or at a brick and mortar retails store, we need to either present a card to the merchant or feed in the card or account details on the website. There are chances of misuse of the card details if proper security measures were not in place. The process is also tedious due to multiple levels of authentication.

With the advent of UPI and BHIM, all this has changed. Online money transfer and payments have never been simpler.

What is UPI

I have explained about UPI in my previous post. But in short, UPI(Unified Payment Interface) helps the financial organisations and clearences houses to use a simpler method for identifying remitter and payee. All it requires is for you to login to BHIM APP create a VPA(virtual Payment Address). This VPA is unique to a user and is in format XXXXX@UPI. Eg. if your phone number linked to a bank account which you choose to register with BHIM is 1234567890, then the VPA can be 1234567890@UPI. If you choose to set it on the basis of name, it can be yourname@UPI or your.name@UPI etc. It’s your choice on the basis of availability.

Note that the prerequisites for using BHIM app are a bank account with phone number linked.

Getting Started

The first thing you will need to do is download the BHIM app. Make sure that you download it from google play store or apple app store. Do not use any other app which you may get via any file sharing site. It could be fake. The link are here for Google Play store and here for Apple itunes store.

Once downloaded, launch the app using the app icon in you app drawer and follow the below slide-show in sequence to set up BHIM.

  • First you will need to verify your mobile number. For a multi-sim device, select the sim which you wish to register with BHIM. This should be the phone number which is linked to you account.
  • Setup a 4 digit pin to access the app. Note that this app doesn’t work on rooted devices.
  • Select the bank which you want to link. The app will display the accounts registered with the bank and linked to the phone number. Select the account you wish to link with BHIM.
  • Setup a 6 digit UPI pin using your debit cards details . You will use this pin for authorising any transaction you wish to carry out.

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Using BHIM

Home Screen

Once setup you can launch BHIM app. You should enter the 4 digit pin which you have set to login to the app. You will be presented with the screen as below.

The various option available on the home screen are as follows:

Clicking the bell icon will display any notification like transfer status, money transfer requests etc.

Send button is used to transfer money to a beneficiary

Request button is used to send a money transfer request to a remitter.

Scan & Pay option is used to use the mobile camera to scan a QR code for payment.

Under the the My Information section:

Transactions list out all the successful and failed transactions and their details

Profile gives the details of your profile including your UPI ID

Bank Account list out the bank accounts linked to BHIM. It gives you option to set default account for UPI transactions.

My Beneficiaries list out the beneficiaries added by you. In case you have installed the app fresh, you will have to add beneficiary using this section.

Adding Beneficiary

To add a beneficiary, click on My beneficiaries. If you have not yet setup beneficiary address, the page will be blank with an option to Add UPI ID.

  • Click on it and on the next screen, enter the UPI Id provided by the beneficiary. It could be in the format XXXXXXX@UPI or XXXXXXXX@hdfcbank etc. The XXXXXXX stand for the combination of alpha numeric id.
  • Click on Verify.
  • The app will verify the UPI ID and provide more details of the payee if the verification succeeds.
  • If the details are correct, click on Add Beneficiary.
  • The My Beneficiaries screen will list the newly added beneficiary.

Click through the slide show below for graphical representation.

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Sending Money

To send money to a beneficiary, click on Send button in the home screen.

  • Select the beneficiary to whom you want to send money.
  • Enter the amount and remarks(if any)
  • Click on Confirm in the confirm to pay screen.
  • Enter you 6 digit UPI PIN for the transaction.
  • The last two slides show a successful transaction and the view of the beneficiary Transactions screen.

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Requesting Money Transfer

Your friend owes you some money but you find it embarrassing to ask him. Well no need to ask anymore. Just send a request with remarks and he will get the hint.

To request money, click on Request button on the home screen.

  • Select the UPI ID from whom you want to request money transfer.
  • Enter the amount and any remarks in the next page.
  • Click on Request.
  • The other party will get a notification in the BHIM app.
  • He/She can then decide to approve the request or deny it.
  • If the other party approves, the money will be transferred to your account and you will get a notification. The transfer will be visible in your as will as the other party’s transaction list.

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Scan & Pay

This is a novel method of making payments. You must have seen that a lot of merchants have a sticker near their point of sale counter with a square containing a graphical code. It is called as QR code or a Quick Response Code. BHIM app also gives the facility to pay by scanning a QR code. This QR code contains UPI ID and other details, including the amount to be transferred in many cases. You can download your own QR code which will be visible in the Profile section.

When you want to make a payment, you will need a code from the beneficiary. The procedure to scan and pay is same as the Send option. The only difference is that instead of selecting the beneficiary from the My Beneficiaries option, you should select the Scan & Pay option. You will have to provide the camera access to BHIM app when prompted. The camera window will open up in BHIM and you can hold it about 5-10 cm from the QR Code provided by the merchant.

The beneficiary may also choose to send you the QR code via email or any other electronic format. You can use the option Pick from Gallery in this case. The app will read the QR Code and fill the beneficiary details accordingly. You will need to follow the same procedure as sending money as detailed earlier.

Note that all the transfers are done from and into your Primary account. You have an option to change primary bank account in the Bank Account list.

Going Digital

With the advent of digital age and better internet penetration, people are using BHIM app more widely and soon you should find its application at many more locations.

In case of queries, do contact me. You can also contact the official twitter handle of UPI and BHIM and they will be more than happy to help you out. The twitter handles are @UPI_NPCI and @NPCI_BHIM.

Sep 212017

Myth : My House is always free from Pollutants

We always live under the impression that pollution exists everywhere but in our house. It may be because we  take trouble cleaning it thoroughly every alternate week. Or we keep the windows closed all the time. We assume that all our measures are sufficient to keep the germs and harmful pollutants out of your homes.

Reality : Your house may harbor more harmful pollutants than you think

Organic Pollutants

As a matter of fact, the air in the surrounding might be much safer than the air inside your house. Here’s why……

  • Your house is a confined space which restricts air flow due to walls. Rarely do we see a well ventilated house in city. The fear of vehicle emissions entering in our personal space, force us to keep the windows closed too. The result is that the air inside remains stagnant. Time and again when we open the doors, we inadvertently exchange only the surrounding air pockets. So ideally, we are breathing air which has higher contents of our exhaled CO2. If any of our family member suffers from an infection which transfers via air, we inhale that too. This increases our chance of catching the infection.
  • The second source of harmful pollutants are dust-mites. Any asthmatic person will know this terms. These are microscopic organisms which are present in our surrounding, largely in fabric. So a curtain which we have not washed since a long time, or a bed spreads which we do not changed frequently, are the likely places where we find the dust-mites breeding. They feed on dead skin and breed in damp environment. And the source for this is our dead skin which we shed unknowingly every day, and our sweat which is absorbed in the bed spreads. Presence of humidity in air will also help breeding this tiny enemies.
  • Mold is another pollutant in your house. You will normally observe it in damp environment, especially on furniture which is not been used. Are you neglected wiping off the surface of the wooden  cupboard door? Observe carefully and you will find layer of fungus growth. This can start fungal infection on your skin leading to various skin diseases.
Chemical Pollutants

Your house can also contain certain chemical pollutants. Below is a list of few with their source and the effects they have.

  • Acidic Fumes: The cleaning agents which we use in our house, especially the bathroom, normally contain acidic components in various proportions. These chemicals give out acidic fumes when exposed to air. These fumes are harmful to health and can cause nausea, irritation to eyes, inflammation of breathing track etc. If inhaled in large quantity, these can lead to death too.
  • Lead: Lead is the primary culprit of brain damage in growing kids. Low quality paint on toys and walls of our house can contain large amount lead primarily. If we ingest the paint flakes, it can lead to lead poisoning and possible neural damage.
  • Aerosol Sprays: The aerosol sprays contain chemicals like formaldehyde and xylene, which are toxins. The next time you are “freshening up” your room, consider checking the contents. These ingredients are carcinogens and neurotoxins which are harmful to human bodies.

Prevention: Here’s how you safeguard you homes

Organic Pollutants

If you have read carefully, you will notice that the one very important aspect which encourages organic pollutants is presence of damp atmosphere and lack of air circulation. If you ensure that you house remains dry and well ventilates, you have solved half your problems

  • When you wake up in the morning, keep your windows open. Let the sun rays and morning fresh air enter your rooms. Fresh air ventilates the room and carries out the accumulated carbon dioxide and other dust borne microbes. Sunlight removes the humidity from air thus prevents growth of fungus and dust mites. It is also advisable not to fold your bed covers after you wake up. Keep them spread-out shabbily so that they too become dry and prohibit these microbes from breeding. Change the sheets regularly.
  • Along with your floors, also clean your walls, ceiling and wooden furniture once in a while. This will help remove dust which normally settles on flat surface.
  • If you are using air conditioner, clean the filters of the indoor unit. These filters normally accumulate a lot of dust which can be a breeding ground for dust-mites. Carpets and curtains too tend to absorb lot of dust. A powerful vacuum cleaner can do the trick.
Chemical Pollutants
  • Avoid chemical cleaning solvents. Search for herbal solutions for cleaning as far as possible. In case not feasible, use the chemicals only in well ventilated room, if possible, with exhaust fan running.
  • Avoid chemical based aerosols as room fresheners. You can use natural solution like scented candles. Fresh flowers are a very good source of mild fragrances. Keep a vase full of them and change them daily. Just ensure that none of your family members are allergic to pollen.
  • Use good quality paints. Check the contents of the paints. It should not contain harmful toxins like formaldehyde. One such paint is Asian Paints Royale Atmos . This paint contains activated carbon which absorbs bad odors and released mild fragrances. The paint follows strict international and safety standards. The carcinogens content in it is very less. It is also washable. The Royale Atmos helps you get cleaner and fresher air in your homes.

For more info check https://www.asianpaints.com/atmos


Sep 202017

 Games and Us

We all play various games in our life. Right from the childhood, when we used to play outdoor games way back in the 80’s and 90’s to the indoor digital games which we play currently. The games included Cricket, football, Badminton, Chess etc in those days whereas currently all these games are digitized.

Digitization of games has its own advantages and disadvantages. The main disadvantage is that we tend to reduce the movement of our body, which normally we associate with these games. But the advantage is that we get to play against the world community as against the local community. This can help us develop our skill in a particular game, much better.

This is mostly true for certain indoor games which require more use of brain than muscle. No one can replace physical sports like football with digitized games and yet maintain the level of physical involvement required. Or may be I am wrong, time will tell.

Here in this post, I will help you learn to play Sudoku. Sudoku is primarily a number game. It involves use of basic math reading, no calculation required. If you know which numbers lie between 1 and 9, you qualify for taking this lesson.

Sudoku primarily appeared in newspapers but programmers have digitized this game. They have also added certain difficulty measures to it, one of them being time constrain. Playing Sudoku under time constrain will help you in improving your logical thought process and keeps your brain active. This also helps reduce the chance Alzheimer. And it’s fun too.

So let’s begin.

Playing Sudoku

 The view

Once you launch Sudoku in your computer or mobile phone, the screen will show a square subdivided in to 9 equal sub-squares. Each of these smaller squares are further subdivided in to 9 equal cells. This 9 X 9 configuration is a standard configuration in any version of Sudoku. Refer picture on left.

You can see few digits entered in cells. Note that the numbers are completely random. But still there exists a logic in their placement. You will understand it once we move ahead.

As you can see, the big outer square is sub divided in to nine smaller sub-squares. I have marked one of them in green. Each of these smaller sub-squares is subdivided in to nine smaller cells. I have marked two of them in red. We must fill up the blank cells to complete the puzzle.

 Game Rules

The rules for the game are pretty simple. All you should do is fill up the empty cells with following constrains in mind:

  • Each sub-square(green) must contain the numbers from 1 to 9 without repetition.
  • Also, each vertical column must contain the numbers from 1 to 9 without repetition.
  • And each horizontal row must contain the numbers from 1 to 9 without repetition.

Straight forward,isn’t it? It is if you follow certain tips and tricks. The level of difficulty you select while launching the game defines this. The difficulty level depends more on which cells are pre-filled with respect to blank cells rather than the number of pre-filled cells. I suggest that a new user should start with easier levels, to get a hang of it.

For the sake of explanation, I have numbered the cells as below. If you use excel, you will be very familiar with this cell address scheme. You may or may not see this numbering scheme in the game depending the developer. We refer to the first row first column as a1, first row second column as a2 and so on up to i9.

Game Play Tips and Tricks

This game is played using the process of elimination. First of all, look up for any sub-square which has the maximum pre-filled digits. You can see in our example above that there quite a few sub-squares. Pick up any one of these sub squares and start counting from 1 to 9 while checking which number is missing.

Playing the Sub-Squares

Let’s say the we are playing with the very first sub-square contained by the cells a1 to c3. We see that the number 1 is missing. There are 5 empty cells in the square a1-c3. But when we take in to consideration the rules, only two cells qualify to accommodate the number 1. These cells are a1 and c1. The cell b2 cannot contain the number 1 because the cell d2 contains the number 1. Similarly a3 cannot contain the number on because the cell g3 contains the number 1. If we place the number 1 in b2 or a3, this would be repetition, which is against the rules.

So now we have the cells a1 and c1 where we can possibly place the number 1. But there is no way at this moment to tell where we should place number 1 without having a conflict in future. So we move forward.

Counting ahead, numbers, 2, 3, 4 and 5 are already present in the sub-square. Number 6 is not present. We can place number 6 in either a1 or a3, but we are not sure even in this case whether there will be future conflict. Same is the case with numbers 7 and 8. Number 9 is already present in the sub-square. So we move forward to analyzing sub-square a4 to c6.

In this, while counting we find that numbers 1, 4, 5, 8, 9 are in same situation as previous sub-square and numbers 2, 3, 6, 7 are already present.

We keep on moving forward among these sub-squares. In sub-square a7-c9 we are able to fill in number 3 at cell b8. This is because it is the only cell which allows the missing 3 to be entered without conflicting with all the already present 3s highlighted in red.

We can keep on analyzing in this way and we come up the final result as below.

Since we have entered few numbered in blank cells in the first iteration, we have to go back and carry out second iteration. Since we have filled up some numbers, they might help us to determine those cells where we not sure previously. We keep on repeating these iterations till we are not able to enter any single number in the entire iteration.

The final matrix after multiple iterations in example above is as below.

Playing the Columns

Since the difficulty level for the puzzle above was easy, we solved this by analyzing the sub-squares. But as the difficulty increases, analyzing the sub-squares alone will not be sufficient and in such case we need to start analyzing using rows or columns method.

Let’s say we tried iterations number of times but were unable to fill up the matrix as below. Then we can go for the next method.

In this case we start analyzing either each row or each column, one by one. Let’s pick up column 1. We again start counting and checking whether the numbers 1 to 9 are present in that column. If any number is absent, we search for the possible cell where we can fill that number. This is done by checking the corresponding row for each cell.

For example, if we want to check if we can fill a missing number, let’s say number 1 in the above case,  in cell a1, we check cells a2- to a9 for the presence of number 1. If number 1 is not present in cells from a2 to a9, then the cell a1 becomes a possible location for number 1. Now we need to check for any other possible locations in column 1 where we can place number 1. If there is only one cell location in column 1 where we can fill the number 1, then we should fill it. If there are more then one possible locations to fill in the missing number 1, we can’t fill it and we should move ahead analyzing the next number.

Once we analyze one column, we analyze the next column in the same way. We can continue this for number of iteration till we either solve the puzzle or we are not able to fill up any number in a single iteration.

Playing the Rows

Once we are not able to fill up any number in a single column iteration but are are left with blank cells, we should start analyzing rows.

Analyzing the rows and filling them ups is same as analyzing the columns as explained above. In this we check the possibility of filling up each cell of the row by cross checking them against the corresponding column. Once done with one row, we mode on to the next row.

Spotting the Numbers

Another method which we can use along with the above three is singling out an individual number and checking their position in the matrix. This method, though similar to analyzing each sub-square, is different from it because in this method, we analyze a particular number. The presence and position of this number in corresponding horizontal and vertical sub-squares determine the position in the sub-square where it is not present.

Let’s take an example of number 5.

You can see that the number 5 appears in each sub-square except in the sub-square a4 to c6. There are four cells empty in a4 to c6. These cells are a4, a6, b5 and b6. Cell a4 abd a6 cannot contain number 5 because cells g5, a8, d6 conflicts. Similarly cell b6 cannot contain number 5 because cell d6 conflicts. So cell b5 is the only cell where we can place number 5.

This analysis can be done starting from number 1 to 9 in sequence.

Mixing it Up

We can even opt for mixing these methods instead of carrying out multiple iteration of each method. For example, we can start with analysis of rows, complete one iteration then move to next method, say column analysis for one iteration and then sub-squares for one iteration and number analysis. Mixing and matching can keep things interesting.


So you see, Sudoku is not a difficult game. It just needs few tricks and some practice.

If this article has helped you learn Sudoku, kindly share it across. Leave comments if any help needed.


Sep 152017

What is Aadhar about?

India is turning in to a digitally enabled country and the role of Aadhar(unique identification number) can be considered as pivotal. Though it took some time to gain momentum, Aadhar has started rolling along with speed and we keep on seeing large number of government and private services being linked to Aadhar. The latest in the list of services which was linked recently was PAN card details. Going forward, it will be mandatory to link phone number to your Aadhar number.

Aadhar is a 12 digit unique identification number which identifies an individual. Aadhar details currently contain lots of personal data including address, date of birth, phone number, biometric data etc. This data is used to provide various services while authenticating the identity via backend data servers. So naturally it is of prime importance that Aadhar data stays secure. If it falls in wrong hands, it could be misused resulting in unwanted losses and unpleasant events.

How to enable Aadhar biometric Authentication Lock

There is a way in which this data can be locked to prevent unauthorised use and unlocked whenever required. For that, you will need to go on to Aadhar webpage here.

Important : You need to have a phone number linked to your Aadhar before you can proceed. In case you do not have a phone number linked to Aadhar, you should visit a Aadhar enrolment center to get it linked.

So continuing, once you are on the webpage, you will be greeted with the front page as shown below

Click on “Lock/Unlock Biometrics” shown in the circle. You will get a pop up in which you have to click on “OK”

It will take you to another webpage which details out how the Lock/Unlock affects your Aadhar. Read it carefully. In brief it says:

  • If you lock the Aadhar, you will not be able to use biometric authentication.
  • To be able to use biometric authentication, you need to unlock it temporarily or disable the lock.

Remember if you Lock Aadhar, you should unlock it first before attempting biometric authentication for any service.

Now when you scroll down on the page, you will find the login page. Enter your Aadhar number and the security code displayed in the window. Then click on “Send OTP” button.

Next, you will get a One Time Password on your mobile(OTP) and the OTP entry field will be enabled along with Login button. Enter the OTP and click on Login.

This will take you to a page which gives you Aadhar biometric authentication service status. To enable the biometric lock and thus disabling biometric authentication using Aadhar, enter the security code and click “Enable”.

If you have done all the process in correct manner, your biometric authentication will be locked and the status will be displayed on next page as below.

How to disable Aadhar biometric Authentication Lock

To disable the lock, login using your Aadhar number and OTP as mentioned above. Once you are logged in, you will be greeted with a page which allows you to either temporarily unlock or disable the lock completely.

Enter the security code and click on the button of your choice(Unlock or Disable).

If you unlock the biometric authentication temporarily, it will be unlocked for only 10 minutes and will automatically get re-locked after 10 minutes.

If you disable the biometric authentication, it will be disabled permanently until you re-lock it using the above mentioned procedure.

Remember, if you lock biometric authentication ,you should unlock before you try to authenticate using biometrics for any service.

Sep 022017

The existence of a new real life game called “Blue whale” and the incidents of suicides related to it are all over the news. Quite scary to read. How few unknown people can take control of your life without ever meeting you, points towards the various dangers lurking out there in the digital world. We have to stay alert and keep ourselves protected from these dangers. And ensure that our kids are protected too. Modern age parents take pride in the facts that their kid of age 2 years very easily navigates through their phones, click photos on them, run apps like YouTube and make their parents proud. Have we ever wondered that the kids learn things very fast and it might be so that they manage to learn thing which even we adults find difficult. For example, installing an unwanted/forbidden app and using it without our knowledge. Its true that new generation kids shouldn’t be deprived of access to technology, but parents need to control and monitor properly.

Coming back to Blue Whale, it is said that it is not an app, but a social network group/page/whatever you may call it, which lures people in to taking up unearthly challenges and ending these challenges with the ultimate challenge to commit suicide. The facts are not yet clear but certain things are. It is not an app. Atleast not an app on Google Play Store or iphone App Store. These stores are monitored and controlled very closely and such a game would not have passed their scrutiny so easily. So even if it was an app, or ever is converted in to an installable app, it will be available via uncontrolled third party app stores or as a third party app which can be installed by clicking suspicious links. But the security features in Android and iOS doesn’t let you install such apps so easily, and even has security features which disable installation of third party apps. My advice, enable these security features first.

You can take certain measures to ensure that unwanted apps are not present on your phone.

Disabling installation of Apps from unknown source:

In android settings under security options, find the option “Unknown Source” and disable it. If this is enabled, you are giving access to installation of third party unverified application. If your kids click on unverified insecure links, these apps can be easily hidden behind the link and can get downloaded.

Uninstalling suspicious apps:

Now-a-days, all apps are required to ask for permission to certain device features which are security sensitive. Eg. access to your SMS application, phone book, camera etc. If you install an app which, when launched, requests permission to certain features which its doesn’t have any business asking for, do not give the access and uninstall it if it is not important. Ask the developer via the feedback regarding this access request if this app is very much required by you and give access only once you are sure what you are doing. For example, certain games ask access to phone book. This is required in case they have a feature where you can invite your friends on the phonebook to download the same app and play with you. But in case the app has no such feature, it has no business asking for phone book access. Its better to uninstall it rather than give them all information about your contacts.

Do not Root the phone:

In case you use lots of apps which are financially sensitive, like banking apps, on your mobile, do not root your phone. Even if you root the phone, ensure you give access only to legitimate verified apps, which really need the root access for their usage. The rooting of a phone is equivalent to giving administration access on your windows computer of super user access on Linux. A normal phone user doesn’t need root a phone as all his work can be done without root. Rooting is done only by super users who try to squeeze every bit out of their phones and a little bit more. They are the nerd and know what they are doing.

Update you phones regularly:

Keep on checking your phone for updates and update it as son as you get one. A good mobile manufacturer provides updates with latest security patches and features. These patches close any backdoors which might have been present in your phone which can give unauthorized access to a third party.

Coming to Blue Whale and securing your kids, there is nothing in this world which can protect them other than you. Keep an eye on their digital habits and their real life habits. You, as a parent, can easily detect any change in their habits and find the cause. No amount of other digital security can protect your kids as much as your sharp eyes on them.

Aug 302017

In my last post, I had promised to come back with a guide on setting up your Pi as a media server. It has been some time now, but here it follows.

Before we begin, how about some insight to media servers and certain technology standard called DLNA?

We all have a lots of media lying around in various storage devices and we(some of us at least) still use the stone age methods of transferring media to our media players(USB stick to use on smart TV, phones, tablets etc.). How good it would be if we were able to access our media right from its source without getting up from the chair!!

Enter media servers. These are a bit of software running on a network connected computer, which organise, and share your media to anyone connected on to the network. To unify the way these network connected devices access media, a certification standard was formulated by various electronics giants like Sony. The basic idea behind formulating this standard was to ensure that media can be accessed across various platforms with ease. So the media content might be on a windows based server but it could be accessed by DLNA compliant devices which could range from a smart TV with proprietary operating system, or a android based mobile phone(android was just in making back then but the standard was platform independent so could be adopted at a later stage easily) or even a linux based computer. More information on DLNA of Digital Living Network Alliance can be found here.

Anyway, if you are following this guide, it means you are a potential candidate to setup media server on your home network. This guide is specific to Raspbian OS and the prerequisites are to have a Raspberry Pi which is connected to your network(via wired network preferably) and your HDDs with the media folders mounted to an accessible folder. You can follow the guides in my previous posts here and here for that.

Let’s begin!!

Login to you pi via SSH. Remember we are running the device headless since we want to conserve the processing power. In case you are still using desktop, you can launch terminal from the desktop.

First ensure that your Raspbian installation is up-to-date. Run the following commands for that.

sudo apt-get update

sudo apt-get upgrade

Next install minidlna using:

sudo apt-get install minidlna

Once installed, backup the minidlna configuration file using:

sudo cp /etc/minidlna.conf /etc/backup_minidlna.conf

Open the minidlna configuration file in nano for editing using:

sudo nano /etc/minidlna.conf

(you can use sudo leafpad /etc/minidlna.conf to open in leafpad in case you are working on desktop instead of terminal)

In the configuration file, find(using up/dn arrow keys) db_dir and set its value to :


Remember, most of these settings are commented out using #. Remove the # to uncomment them and make them usable.

Set minidlna media directories to point at the directories which hold your media as follows:

media_dir=V, /media/WD/movies

Here “V” stands for Videos. For specifying aa audio directory, use “A” and “P” for photos . The above line in the configuration file will specify that one of the media directory to scan for video files only is located /media/WD/movies. I have used WD since I have mounted one of my HDD at /media/WD and the “movies” is a folder in that HDD which contains movies. You will certainly have a different configuration so check your setup and edit this line accordingly.

If you are specifying media_dir=V, /XXX/XXXX/XXX, the server will only serve video files to the network. If you do not specify “V”, it will search for all media contents in music, photos, videos. So the line can also be :


You can have multiple configuration lines here. But I suggest you organise the media properly before sharing else your media devices will show you a lot of directories and you will find it difficult to locate specific media in them.

In friendly_name suggest a recognisable name. Mine is :

friendly_name=Raspberry Pi MiniDLNA

You can have anything you like.

Uncomment out the inotify=yes so that the server keeps on searching for new media, whenever you add new files.

Now click ctrl+x.. It will as whether to save the file. Select yes. Then run the following commands.

sudo service minidlna restart

sudo service minidlna force-reload

To ensure minidlna service starts at reboot run the command:

sudo update-rc.d minidlna defaults

No go for a reboot once using:

sudo reboot

If you have done everything right, upon reboot you should be able to see your media server on you DLNA compliant devices, or DLNA media player softwares.

Do ping me in case you have trouble.

Jul 232017

It’s a very common thing to have multiple hard drives in our possession these days. With all the data and media that we have with us, the inbuilt storage in our computers prove insufficient. External HDDs also provide easy portability for the media. But we always face an issue when we want to share our media or even the HDD space with others in our own home or on our internal network. One solution is to attach the HDD to the computer and configure it as a shared drive. But that would require a computer which is running 24×7 so that the drives are available at any given time to anyone. Not an ideal solution.

Another method is to configure a NAS or Network Attached Storage. NAS is basically a storage attached to a network device(typically a server, but can also be a dedicated controller) which is connected to a network and runs 24X7. You do get NAS devices in market but these devices are typically as costly as a single 2TB drive and are normally beneficial for higher speed transfers. The NAS configuration which I plan to discuss here, will give you transfer speeds of about 4-5 mbps over local network and should be suitable for home/home office networks. And we use a versatile computer which has very low footprint in terms of space and power consumption. The Raspberry Pi is one of the best suited computer board for this project.

Before you go further you need:

  • A Pi with Raspbian installed and connected over you local network. Use this tutorial for the same.
  • A powered USB hub sufficient to power your HDDs. Buy here based on number of HDDs you have

Warning : Do not attempt to power up your HDDs via the Raspberry Pi USB ports since the pi can handle only about 2.5 amps of current through it and may burn out in case overloaded.

So let’s get started.

(Note : This guide has been drafted based on my installation experience, which was further assisted by the guides available at howtogeek.com and instructables.com . Any errors during the installation, you can leave me a note or you can check the guides on their websites. Both websites listed different methods and I couldn’t get mine configured using them individually. But I succeeded when I followed both the guides together)

  • Connect your HDDs to the USB hub and connect the Hub to one of the USB ports on the Pi.
  • Open up shell via SSH( or terminal in case you have connected the keyboard/mouse and screen to your Pi)
  • Run the commands sudo apt-get update and sudo apt-get upgrade to update your Pi installation and repositories.
  • If your HDDs are NTFS format, you will need to run the following command in terminal.

sudo apt-get install ntfs-3g

This will get you Pi ready to understand the ntfs format on your HDDs.

Next step is to identify your drives

  • Type ls –l /dev/disk/by-uuid
  • The output of this command will be similar to below:


  • Here sda1, sdb1, sdc1 denotes the external HDDs. The number will vary as per the HDDs connected by you. We are interested in the 16 digit hexadecimal UUID against each of these. Note down the 16 digit codes and the corresponding HDD identifiers. eg. sda1 – 1C0CA2830CA25812 in the example above.
  • Next run code ls –l /dev/disk/by-label
  • The output will be something like this:


  • As you can see, my labels are Transcend, Storite and WD for sda1, sdb1 and sdc1 respectively. These are the actual labels which you have given to the HDDs. Note these down and match them with the UUID. So in my case it will be sda1 – 1C0CA2830CA25812 – Transcend.
  • Now that we have identified the HDDs, we need to mount these drives. But before that we create a location to mount these drives.
  • Run code sudo mkdir /media/DRIVE_NAME . eg. for my transcend drive, I created directory using sudo mkdir /media/transcend
  • Do this for all the drives that your have connected.
  • Next, mount each drive with the following command for each instance:

sudo mount -t ntfs-3g -o uid=pi,gid=pi /dev/sdxx /media/DRIVE_NAME

  • Where sdxx is sda1, sdb1, sdc1 etc and DRIVE_NAME is the corresponding mount point which you created earlier. So for my transcend drive the command will be:

sudo mount -t ntfs-3g -o uid=pi,gid=pi /dev/sda1 /media/transcend

  • Do this for all the drives.
  • If you have fat32 or ext4 drives, suitably modify the command:
  • ntfs-3g for NTFS drives
  • vfat for FAT32 drives
  • ext4 for ext4 drives
  • The drives should mount everytime we reboot. So we need to add it to startup script.
  • Run sudo cp /etc/fstab /etc/backup_fstab
  • Then run sudo nano /etc/fstab
  • Add the following correspondint to each drive

/dev/sda1 /media/transcend auto noatime 0 0

Use the correct drive identified sdxx and the corresponding correct DRIVE_NAME for each HDD.

  • Restart the Pi using sudo reboot
  • Next step is to install samba.
  • Run sudo apt-get samba samba-common-bin
  • Once installed, backup the samba configuration file before proceeding:

sudo cp /etc/samba/smb.conf /etc/samba/backup_smb.conf

  • Run sudo nano /etc/samba/smb.conf
  • In the configuration file that opens up, ensure that the workgroup is your local workgroup for your network. Ideally its WORKGROUP for windows. Modify it if you are using something else.
  • In the Authentication section, enter security = user to enable verification
  • Now scroll to the bottom of the file and add your drives as follows:


  • Here valid user = @pi is the username I selected. You may select anything you want eg. valid users = @josh .
  • You may also choose to share specific folders inside the HDD instead of the entire HDD. Modify path if that is the case. The read only attribute specifies the modification rights and the no flag specifies that the users on network can read as well as write to the shared drive/folder.
  • Save using ctrl+X, say yes and hit enter.
  • Run sudo /etc/init.d/samba restart
  • Add user to give access to the shared drive
  • sudo useradd josh -m -G users
  • sudo passwd josh
  • You will be prompted to enter a password twice.
  • Next enter the command sudo smbpasswd –a josh
  • Create password on prompt
  • Restart samba using sudo service smbd restart
  • The HDDs should be visible to you on other computers on your network. You can configure it as a network drive. You will need to specify username and password once for access.

Next time, we will see how to configure DLNA server on your Pi to share the media files to your DLNA compliant devices.

Jul 162017

If you follow tech world, you must surely have come across the name “Raspberry Pi” which has been making waves in its field for about 5 years. I had provided a basic insight regarding credit card sized(and thumbnail sized) computers in my previous post. These tiny boards cost from about 5$ to well over 100$, each with its own specialties. And they are the favorites of the geeks for small tasks, dedicated application or plain hobby projects.

But its not just the geeks who have the competence to use them. A common person like any of us can pick one up and configure with a little bit of research(nothing anyone can’t handle. Some basic configurations are straight forward.) You can use it as a simple linux based computer, a media server, a network attached storage controller, create a magic mirror, an interactive AI and pretty much anything you may want with a bit of advance tutorials.

The aim of my todays blog is to guide you through the installation of Raspbian and create a backup image of the setup. The back up will help you to copy the sd card in an image format which can be overwritten anytime you feel that the OS is not behaving well. I will also explain how to setup your pi to be used via a remote computer, thus dispensing the need to connect it to a monitor, mouse or keyboard. We shall set it up so that the pi is on static IP and easily accessible via shell or via VNC.

Note that the Raspbian OS is based on Debian distribution of Linux, so even though you get a GUI, be prepared to try out command line for advance configurations. They are fun to learn and not very difficult to remember(or to google for that matter)

What you need

  • A Raspberry Pi 3 with a 2.5 A 5V power supply(micro usb pin)– buy it here and here
  • A 16GB – 32GB micro SD Class 10 card – better a 32 GB version if you plan to setup more number of applications – buy it here
  • A keyboard/mouse/monitor(HDMI TV will do) for initial setup
  • NOOBS – download here (NOOBS is a “New out of Box Software”, a minimal intervention installer with OS packages built in)

Whenever you plan to buy a case for the pi, consider possibility of adding a fan and GPIO headers. Also consider that you may need to remove the micro SD card time and again in case you are using another card for another project. Make sure that the SD card is readily accessible.

Install Raspbian

Before you try to install raspbian on to your sd card, you will need to format in to Fat32 file system. You can use SDformatter for the purpose. Once the SC card is formatted, extract the downloaded NOOBS image in to the root of the SD card.

The installation method below gives the installations of only Raspbian OS with PIXEL desktop. You should be able to install and use any other OS listed within the list, once you are a little familiar with how it works.

  • Insert the card in to you pi in the card slot.
  • Connect the HDMI cable, keyboard and mouse to the pi.
  • Connect the power source.
  • The pi will start automatically. You will be taken to the list of available/downloadable OSes. Select Raspbian jessie with full desktop.


  • On the top left hand corner, you will find a icon shaped like a hdd. It is your install button. Click on the button to install Raspbian.
  • Go have a cup of tea cause it takes 15-20 minutes to install. Yes, no further intervention necessary.
  • When you come back from your short break, you will be greeted with a message saying that OS is installed. Click ok. The system will reboot.

That completes the installation part. Once the system reboots, it will take you to the PIXEL desktop. It is essentially similar to windows desktop with the taskbar and menu docked to the top. But don’t let the appearances fool you. The core on which it is built is rock solid, highly customizable and very secure.

The round raspberry on top left gets the things started for you. Navigate around to get a feel. The other important icons which you would be using time and again are:

  • The blue globe near the raspberry, which is essentially the web browser.
  • The folder icon, which is used to navigate the file system
  • The black window, which I guess you know from your windows days, the console or the terminal

Navigate around the icons, they wont kill the system for now.


Let’s change the default password

Ok, first thing’s first. We secure out pi before we connect it to network. Click on the terminal icon. The terminal, as below, will open up.


Here, the “pi” is the current user and raspberrypi is the hostname. Let’s change the password. Type the following code in front of the prompt:


You will be prompted to enter the current password. The factory default password for user pi is raspberry. Enter the password and you will be asked to type in the new password, two times. Enter it twice and the password will be changed.


Let’s setup static IP

Setting up a static Ip to your pi makes it easy to access it from another machine

  • Open terminal and type in sudo nano /etc/dhcpcd.conf
  • Here sudo mean you are telling the system to do something as a superuser. Something similar to run as administrator in windows.
  • nano is a text editor for terminal. another text editor available for GUI is leafpad. So when you are logged into desktop, you can type in sudo leafpad…… instead of sudo nano….. But it is a good practice to use nano since, once we switch off the GUI, console is all that you have until you switch it back on again. You will be able to use only the arrow keys and enter button in nano.
  • dhcpcd.conf is the configuration file for the network and etc is the directory where it is stored
  • scroll down to the bottom of the file that opens up and type in the following code:

(Edit 19 August 2017 : Raspberry Pi foundation has released the new version of Raspbian codenamed Stretch(old was Jessie). The procedure for setting up static IP is different and listed below)

interface eth0

static ip_address=

static routers=

static domain_name_servers=

interface wlan0

static ip_address=

static routers=

static domain_name_servers=

In the above code:

  • you can use either wlan0 or eth0 or both, depending on what kind of connectivity you plan. wlan0 is for wifi and eth0 is for wired connection.
  • static ip can be of your choice based on your network configuration (eg. some networks are configures 192.168.0.xxx). Make sure to keep the number /24 in the settings.
  • static router specifies the router to which the pi is to be connected. My router ip is
  • similarly static domain name servers can be as per your network configuration. My home network devices get their DNS from my router so I have entered my router address.’’
  • Press ctrl + S to save the settings.
  • Press ctrl + X to close the editor.

Edit 19 August 2017 : New procedure to setup static IP on Raspbian Stretch follows

In Raspbian Stretch, the network interface is no longer recognised as eth0 or wlan0. So we need to first find what it is called(different for different machines.)

  • type command ifconfig
  • you should get results like below

enxxxxxxxxxxxxx: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet netmask broadcast
inet6 fe80::35e0:4ba4:69da:a857 prefixlen 64 scopeid 0x20<link>
ether b8:27:eb:2d:0c:50 txqueuelen 1000 (Ethernet)
RX packets 22310 bytes 13188104 (12.5 MiB)
RX errors 0 dropped 6 overruns 0 frame 0
TX packets 11464 bytes 6083883 (5.8 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet netmask
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 1 (Local Loopback)
RX packets 25 bytes 1484 (1.4 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 25 bytes 1484 (1.4 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0

  • The entire alphanumeric code above in yellow is how my eth0 is recognised. It will be something else for you.
  • Now type command sudo nano /etc/dhcpcd.conf
  • At the bottom of the file that opens up, add the following. Ensure you add the correct addresses for your network setup.

interface enxxxxxxxxxxxxx
static ip_address=
static routers=
static domain_name_servers=

You can now connect to the home wifi, of ethernet, or both. The up and down arrow on your top right hand side of desktop will help you join a wifi network.

Once connected to internet, it would be a good practice to update your system before you go further.

Open the terminal and type in sudo apt-get update. Once this command is executed, use sudo apt-get upgrade. It is a good practice to use this two commands before installing any new software on your pi. They are used to update any packages which are installed on your pi and which have been updated ever since you installed. Fresh OS installations normally have some major updates available.

Let’s do away with that monitor, keyboard and mouse(Optional if you are comfortable running the show remotely via terminal. But that’s what these board is all about….accepting the challenge)

So now that you have changed password and set up static IP, let’s go a bit deep and dispense away that monitor. Only of course if you have a computer or a laptop from where you can control it. Remember, though the pi can be used as a regular desktop computer, it will run only may be one or two applications together because it simple lacks the resources needed for heavy multitasking. It is best suited for headless apps and servers, similar to ones which I have listed out in the beginning.

Open the terminal and type in sudo raspi-config

  • This will open the configuration tools for raspberry pi. Thins this as a BIOS for your PC with more configurations.


  • Use the arrow keys and enter button to select Interfacing Options.
  • Select SSH and enable it. Next Select VNC and enable it. Selection is by pressing enter and arrow keys.


  • Select Back.
  • Select Boot Options
  • Select Desktop/CLI
  • Select B2 Console auto login.


  • Select finish and reboot.
  • Move over to your regular use PC.
  • Download and install a SSH client like putty. Run Putty on your pc.
  • Enter the IP address in the hostname field, enter a recognizable name in saved session field and click save


  • Now double click on your saved session and a terminal window should open up asking you to enter username. Enter pi.
  • Next enter the password which you have set.
  • This will take you to console from where you can control your pi.


Since you have configured only console login via configuration tools, you can access only via putty(SSH). If you configure to boot in desktop mode via configuration tools, you can use VNC to login to desktop too. You will need to download VCN on your computer to do that. Try it out, its easy. If in doubt, just leave a query. You can always go back to desktop login by using sudo raspi-config.

Let’s backup

Let’s try the easy way to backup today.

  • Download win32 disk imager and install on your computer.
  • Shut down the raspberry pi, remove the card and insert it in your computer(via SD card reader)
  • Run win32 diskimager.
  • Select the device to backup(our sd card).
  • Select a backup location on your computer and give a file name (eg, raspbianbackup.img)
  • Click on Read


  • The backup will automatically be created at the specified location.
  • Next time, the setup on you pi doesn’t work as it should, run this program again and select this image we have created. Click write instead of read this time, to overwrite on the card.

In case you have any doubts or anything very clear or seems to be wrong, kindly leave a comment. In the next tutorial I plan to explain setting up a NAS server, a DLNA server and an always on bit torrent box.

Till then!!

Nov 062011

Fish as a Health Food

It has been said time and again that fish is a health food. We, living in coastal region, have access to plenty of it and so it has been our daily diet for ages. The most common method of preparing fish in my region has been cooking it in tamarind & curry leaves based curry. Fried fish as a side dish has been the second most favored choice. It’s hard to pass a day when one of our meal doesn’t contain fish.

Having said that, we do understand that in many cases, fish can be as harmful to your cholesterol levels as red meat. Shelled fishes are known to increase cholesterol count, so don’t consider yourself healthy if you eat a lot of crabs and lobsters. There are lot other fishes which are known to carry toxic elements in their body. But I am not writing this to wake your health concerns. This post is to let you know that the cook in me is still alive and cooking. I am experimenting on steamed fishes, and have been achieving better results each time. Though there are variety of fishes which can be steamed, I restrict myself to pomfret as the flesh becomes very soft after cooking. You can also steam Kingfish, mackerel and other types of fish as per your liking.

….….…Wow!! I just took a break from writing to finish off the steamed pomfret which was on the stove while I was writing. I just can’t to wait to share this recipe.

Let’s do it

Ingredients :

(I prefer not to weigh my ingredients because each time you end up having different proportions which creates interesting flavors. Believe me!!Also, you can use the bit extra marinade to go with your appam or rice)

1 Pomfret(size as per your requirement)

4 tablespoon grated coconut(health conscious people can opt out of this ingredient)

1 green chili

1/2 tomato

2 tablespoon olive oil

1 teaspoon cumin seeds

1 teaspoon coriander seeds

1 teaspoon mustard seeds

1 teaspoon ginger garlic paste

handful of fresh cilantro leaves

turmeric leaves or banana leaves(enough to wrap the pomfret and the marinade, OPTIONAL)

a piece of ambi haldi(OPTIONAL, tastes very good when used with turmeric leaves wrapping)

food grade aluminum foil

4-5 curry leaves

salt to taste


Except for the pomfret, aluminum foil, the wrapping leaves and ambi haldi, mix everything in the grinder to make a smooth paste for the marinade/stuffing. Keep aside.

Clean and gut out the pomfret, remove the fins and tail. Remove the mouth, eyes. There are two ways of marinating, one is stuffing and second is applying the marinade on the grooves cut on the fish. I prefer grooves, but if you need assistance on stuffing, check out this video. If you don’t want to stuff, cut deep grooves across the breadth of the fish while keeping the fishbone intact. Apply the marinade generously all over the fish and fill up the mouth cavity.

Cut the ambi haldi in to thin strands and spread all over the fish. Place the fish with its marinade on the turmeric leaves or banana leaves and wrap around gently. Then place this entire wrapping on aluminum foil and wrap around(aluminum foil helps in preserving the juices which might seep out of the leaves). If you don’t have the leaves, you can wrap the fish in the foil itself, but remember, the leaves impart a good natural flavor and aroma to the steamed fish.

Photo1436Use a traditional idli maker to steam the fish. Photo1437It can even be steamed in a pressure cooker with the whistle removed. While steaming ensure that there is enough water to last for about 30 minutes of steaming on low heat, but not so much that the water enters the aluminum foil. In the traditional idli maker, you can use the idli plates to separate the fish from the water. In a pressure cooker use suitable stand which is stable and which can hold the fish.

Finish Garnish and ServePhoto1440

Steam the fish for about 30-35 minutes on medium heat. Garnish with fresh cilantro leaves. Serve hot. While serving, try to retain the juices that flow out of the fish. Goes well with idli, dosa, steamed rice, appam, amboli etc..

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