Sunday, 30 October 2011

How to install sshd and config for authentication with private key only

Once the system is up and running, the first thing for most linux system admin to do is to install sshd and configure authentication. Nowadays, most IT companies will not allow password based authentication anymore. Most coporate environment favours ssh key based authentication. Of course, there are hundreds of different methods to do this. Here is one of my favourite and simplest guide.

I've assumed you use Debian based linux and logon under root. If you are using other linux, change the command to yum or whatever package management system you used.


  • First install ssh server.

  • ~$apt-get install openssh-server


  • Edit sshdconfig file

  • ~$vi /etc/ssh/sshd_config

  • Disable password authentication by putting the following line

  • PasswordAuthentication no

  • For keys file location, I prefer to put in file by user name

  • AuthorizedKeysFile /etc/ssh/keys/%u


  • Save the file


  • Copy the public key of the users and put in /etc/ssh/keys/


  • Restart the ssh demon by entering the following command

  • /etc/init.d/ssh restart


That's it! Your users need to use their private key to login to the server from now on.

Source : OpenBSD

Saturday, 29 October 2011

How to add users into sudoers

First of all, you need to have sudo package installed. You can check if your system have by typing visudo command.
root@SUNNYVALE-133:~# visudo
-su: /usr/sbin/visudo: No such file or directory

If you receive the above error, that means you don't have sudo module. You can install by typing the following command:
root@SUNNYVALE-133:~# apt-get install sudo

Once you've got sudo package installed, you can add users to sudoers file. The following is my sample config.

  • First type visudo command

  • The add the following line under root ALL=(ALL) ALL line
    mysampleuser ALL = (ALL) ALL, NOPASSWD: ALL


That's it! From now on, you can simple type sudo su - whenever you want to become root from your own username.

Source : Debian Wiki

Friday, 28 October 2011

How to resolve "Can't locate DBD/Pg.pm" error

I was having the following perl module missing error.
root@SUNNYVALE-133:/# ./myscript.pl
Can't locate DBD/Pg.pm in @INC (@INC contains: /etc/perl /usr/local/lib/perl/5.10.1 /usr/local/share/perl/5.10.1 /usr/lib/perl5 /usr/share/perl5 /usr/lib/perl/5.10 /usr/share/perl/5.10 /usr/local/lib/site_perl .) at ./myscript.pl line 5.
BEGIN failed--compilation aborted at ./myscript.pl line 5.

Gurus from some forums advised me to do the following.
$cpan
cpan>install DBI
cpan>install DBD::Pg

Even after I've done that, I'm still having the same error message. Eventually I've found out that since I'm using Debian, I should rather just install the perl pg library. The following command is the one that solve my problem.
root@SUNNYVALE-133:/#apt-get install libdbd-pg-perl

I hope this would be helpful to you as well if you're getting the same error message.

Source : Perl DBI Support

Google+ is now available to Enterprise users

Finally the wait is over. For all Google Apps users around the world can rejoice now. You can now sign up for Google Plus social network.

To justify the wait for Google Apps users, they will have access to a few more features than other Google+ users. While you’ll be able to share content publicly or only with your circles, you can also share content with people in your organization even if you haven’t added those people to one of your circles.

Google has also explained the reason for the delay
It took more technical work than we expected to bring Google+ to Google Apps, and we thank you for your patience. This integration is just the beginning. We’ll continue to add features and improve the way that Google+ works with Google Apps, and we encourage you to share your ideas.

So why don't you go ahead and start enabling Google plus for your enterprise users.

Source : Google Enterprise Blog

Friday, 7 October 2011

Stay Hungry. Stay Foolish.

This Standford commencement speech by Steve Jobs is never get old. Now it's the best time to rewatch.

http://www.youtube.com/watch?v=UF8uR6Z6KLc


The following is the full transcript:

I am honored to be with you today at your commencement from one of the finest universities in the world. I never graduated from college. Truth be told, this is the closest I've ever gotten to a college graduation. Today I want to tell you three stories from my life. That's it. No big deal. Just three stories.

The first story is about connecting the dots.

I dropped out of Reed College after the first 6 months, but then stayed around as a drop-in for another 18 months or so before I really quit. So why did I drop out?

It started before I was born. My biological mother was a young, unwed college graduate student, and she decided to put me up for adoption. She felt very strongly that I should be adopted by college graduates, so everything was all set for me to be adopted at birth by a lawyer and his wife. Except that when I popped out they decided at the last minute that they really wanted a girl. So my parents, who were on a waiting list, got a call in the middle of the night asking: "We have an unexpected baby boy; do you want him?" They said: "Of course." My biological mother later found out that my mother had never graduated from college and that my father had never graduated from high school. She refused to sign the final adoption papers. She only relented a few months later when my parents promised that I would someday go to college.

And 17 years later I did go to college. But I naively chose a college that was almost as expensive as Stanford, and all of my working-class parents' savings were being spent on my college tuition. After six months, I couldn't see the value in it. I had no idea what I wanted to do with my life and no idea how college was going to help me figure it out. And here I was spending all of the money my parents had saved their entire life. So I decided to drop out and trust that it would all work out OK. It was pretty scary at the time, but looking back it was one of the best decisions I ever made. The minute I dropped out I could stop taking the required classes that didn't interest me, and begin dropping in on the ones that looked interesting.

It wasn't all romantic. I didn't have a dorm room, so I slept on the floor in friends' rooms, I returned coke bottles for the 5¢ deposits to buy food with, and I would walk the 7 miles across town every Sunday night to get one good meal a week at the Hare Krishna temple. I loved it. And much of what I stumbled into by following my curiosity and intuition turned out to be priceless later on. Let me give you one example:

Reed College at that time offered perhaps the best calligraphy instruction in the country. Throughout the campus every poster, every label on every drawer, was beautifully hand calligraphed. Because I had dropped out and didn't have to take the normal classes, I decided to take a calligraphy class to learn how to do this. I learned about serif and san serif typefaces, about varying the amount of space between different letter combinations, about what makes great typography great. It was beautiful, historical, artistically subtle in a way that science can't capture, and I found it fascinating.

None of this had even a hope of any practical application in my life. But ten years later, when we were designing the first Macintosh computer, it all came back to me. And we designed it all into the Mac. It was the first computer with beautiful typography. If I had never dropped in on that single course in college, the Mac would have never had multiple typefaces or proportionally spaced fonts. And since Windows just copied the Mac, it's likely that no personal computer would have them. If I had never dropped out, I would have never dropped in on this calligraphy class, and personal computers might not have the wonderful typography that they do. Of course it was impossible to connect the dots looking forward when I was in college. But it was very, very clear looking backwards ten years later.

Again, you can't connect the dots looking forward; you can only connect them looking backwards. So you have to trust that the dots will somehow connect in your future. You have to trust in something — your gut, destiny, life, karma, whatever. This approach has never let me down, and it has made all the difference in my life.

My second story is about love and loss.

I was lucky — I found what I loved to do early in life. Woz and I started Apple in my parents garage when I was 20. We worked hard, and in 10 years Apple had grown from just the two of us in a garage into a $2 billion company with over 4000 employees. We had just released our finest creation — the Macintosh — a year earlier, and I had just turned 30. And then I got fired. How can you get fired from a company you started? Well, as Apple grew we hired someone who I thought was very talented to run the company with me, and for the first year or so things went well. But then our visions of the future began to diverge and eventually we had a falling out. When we did, our Board of Directors sided with him. So at 30 I was out. And very publicly out. What had been the focus of my entire adult life was gone, and it was devastating.

I really didn't know what to do for a few months. I felt that I had let the previous generation of entrepreneurs down - that I had dropped the baton as it was being passed to me. I met with David Packard and Bob Noyce and tried to apologize for screwing up so badly. I was a very public failure, and I even thought about running away from the valley. But something slowly began to dawn on me — I still loved what I did. The turn of events at Apple had not changed that one bit. I had been rejected, but I was still in love. And so I decided to start over.

I didn't see it then, but it turned out that getting fired from Apple was the best thing that could have ever happened to me. The heaviness of being successful was replaced by the lightness of being a beginner again, less sure about everything. It freed me to enter one of the most creative periods of my life.

During the next five years, I started a company named NeXT, another company named Pixar, and fell in love with an amazing woman who would become my wife. Pixar went on to create the worlds first computer animated feature film, Toy Story, and is now the most successful animation studio in the world. In a remarkable turn of events, Apple bought NeXT, I returned to Apple, and the technology we developed at NeXT is at the heart of Apple's current renaissance. And Laurene and I have a wonderful family together.

I'm pretty sure none of this would have happened if I hadn't been fired from Apple. It was awful tasting medicine, but I guess the patient needed it. Sometimes life hits you in the head with a brick. Don't lose faith. I'm convinced that the only thing that kept me going was that I loved what I did. You've got to find what you love. And that is as true for your work as it is for your lovers. Your work is going to fill a large part of your life, and the only way to be truly satisfied is to do what you believe is great work. And the only way to do great work is to love what you do. If you haven't found it yet, keep looking. Don't settle. As with all matters of the heart, you'll know when you find it. And, like any great relationship, it just gets better and better as the years roll on. So keep looking until you find it. Don't settle.

My third story is about death.

When I was 17, I read a quote that went something like: "If you live each day as if it was your last, someday you'll most certainly be right." It made an impression on me, and since then, for the past 33 years, I have looked in the mirror every morning and asked myself: "If today were the last day of my life, would I want to do what I am about to do today?" And whenever the answer has been "No" for too many days in a row, I know I need to change something.

Remembering that I'll be dead soon is the most important tool I've ever encountered to help me make the big choices in life. Because almost everything — all external expectations, all pride, all fear of embarrassment or failure - these things just fall away in the face of death, leaving only what is truly important. Remembering that you are going to die is the best way I know to avoid the trap of thinking you have something to lose. You are already naked. There is no reason not to follow your heart.

About a year ago I was diagnosed with cancer. I had a scan at 7:30 in the morning, and it clearly showed a tumor on my pancreas. I didn't even know what a pancreas was. The doctors told me this was almost certainly a type of cancer that is incurable, and that I should expect to live no longer than three to six months. My doctor advised me to go home and get my affairs in order, which is doctor's code for prepare to die. It means to try to tell your kids everything you thought you'd have the next 10 years to tell them in just a few months. It means to make sure everything is buttoned up so that it will be as easy as possible for your family. It means to say your goodbyes.

I lived with that diagnosis all day. Later that evening I had a biopsy, where they stuck an endoscope down my throat, through my stomach and into my intestines, put a needle into my pancreas and got a few cells from the tumor. I was sedated, but my wife, who was there, told me that when they viewed the cells under a microscope the doctors started crying because it turned out to be a very rare form of pancreatic cancer that is curable with surgery. I had the surgery and I'm fine now.

This was the closest I've been to facing death, and I hope it's the closest I get for a few more decades. Having lived through it, I can now say this to you with a bit more certainty than when death was a useful but purely intellectual concept:

No one wants to die. Even people who want to go to heaven don't want to die to get there. And yet death is the destination we all share. No one has ever escaped it. And that is as it should be, because Death is very likely the single best invention of Life. It is Life's change agent. It clears out the old to make way for the new. Right now the new is you, but someday not too long from now, you will gradually become the old and be cleared away. Sorry to be so dramatic, but it is quite true.

Your time is limited, so don't waste it living someone else's life. Don't be trapped by dogma — which is living with the results of other people's thinking. Don't let the noise of others' opinions drown out your own inner voice. And most important, have the courage to follow your heart and intuition. They somehow already know what you truly want to become. Everything else is secondary.

When I was young, there was an amazing publication called The Whole Earth Catalog, which was one of the bibles of my generation. It was created by a fellow named Stewart Brand not far from here in Menlo Park, and he brought it to life with his poetic touch. This was in the late 1960's, before personal computers and desktop publishing, so it was all made with typewriters, scissors, and polaroid cameras. It was sort of like Google in paperback form, 35 years before Google came along: it was idealistic, and overflowing with neat tools and great notions.

Stewart and his team put out several issues of The Whole Earth Catalog, and then when it had run its course, they put out a final issue. It was the mid-1970s, and I was your age. On the back cover of their final issue was a photograph of an early morning country road, the kind you might find yourself hitchhiking on if you were so adventurous. Beneath it were the words: "Stay Hungry. Stay Foolish." It was their farewell message as they signed off. Stay Hungry. Stay Foolish. And I have always wished that for myself. And now, as you graduate to begin anew, I wish that for you.

Stay Hungry. Stay Foolish.

Thank you all very much.



Source : Standford University

Tributes from around the world for Steve Jobs...

From Microsoft co-founder Bill Gates

I’m truly saddened to learn of Steve Jobs’ death. Melinda and I extend our sincere condolences to his family and friends, and to everyone Steve has touched through his work.

Steve and I first met nearly 30 years ago, and have been colleagues, competitors and friends over the course of more than half our lives.

The world rarely sees someone who has had the profound impact Steve has had, the effects of which will be felt for many generations to come.

For those of us lucky enough to get to work with him, it’s been an insanely great honor. I will miss Steve immensely.


From President Barack Obama:

Michelle and I are saddened to learn of the passing of Steve Jobs. Steve was among the greatest of American innovators – brave enough to think differently, bold enough to believe he could change the world, and talented enough to do it.

By building one of the planet’s most successful companies from his garage, he exemplified the spirit of American ingenuity. By making computers personal and putting the internet in our pockets, he made the information revolution not only accessible, but intuitive and fun. And by turning his talents to storytelling, he has brought joy to millions of children and grownups alike. Steve was fond of saying that he lived every day like it was his last. Because he did, he transformed our lives, redefined entire industries, and achieved one of the rarest feats in human history: he changed the way each of us sees the world.

The world has lost a visionary. And there may be no greater tribute to Steve’s success than the fact that much of the world learned of his passing on a device he invented. Michelle and I send our thoughts and prayers to Steve’s wife Laurene, his family, and all those who loved him.


From Google CEO Larry Page:

I am very, very sad to hear the news about Steve. He was a great man with incredible achievements and amazing brilliance. He always seemed to be able to say in very few words what you actually should have been thinking before you thought it. His focus on the user experience above all else has always been an inspiration to me. He was very kind to reach out to me as I became CEO of Google and spend time offering his advice and knowledge even though he was not at all well. My thoughts and Google’s are with his family and the whole Apple family.


From Facebook CEO Mark Zuckerberg:

Steve, thank you for being a mentor and a friend. Thanks for showing that what you build can change the world. I will miss you.

Thursday, 6 October 2011

Steve Jobs has passed away at 56

Well, this is very sad news indeed. Our thoughts go out to his family.

Steve Jobs’ family and Apple have confirmed to the press that Jobs died today. His family issued this statement:

Steve died peacefully today surrounded by his family.

In his public life, Steve was known as a visionary; in his private life, he cherished his family. We are thankful to the many people who have shared their wishes and prayers during the last year of Steve’s illness; a website will be provided for those who wish to offer tributes and memories.

We are grateful for the support and kindness of those who share our feelings for Steve. We know many of you will mourn with us, and we ask that you respect our privacy during our time of grief.


And the following is his successor, Apple's new CEO, Tim Cook’s memo (via AllThingsD):

Team,

I have some very sad news to share with all of you. Steve passed away earlier today.

Apple has lost a visionary and creative genius, and the world has lost an amazing human being. Those of us who have been fortunate enough to know and work with Steve have lost a dear friend and an inspiring mentor. Steve leaves behind a company that only he could have built, and his spirit will forever be the foundation of Apple.

We are planning a celebration of Steve’s extraordinary life for Apple employees that will take place soon. If you would like to share your thoughts, memories and condolences in the interim, you can simply email rememberingsteve@apple.com. No words can adequately express our sadness at Steve’s death or our gratitude for the opportunity to work with him. We will honor his memory by dedicating ourselves to continuing the work he loved so much.

Tim