Tuesday, August 28, 2012

Receiving 'Access Denied' just after typing the username in Putty

Problem: Getting 'Access Denied' just after typing username in putty.

Information: The above problem occurs because of the failure of GSSAPI authentication.

What is GSSAPI?  
Generic Security Services Application Program Interface(GSSAPI) is a ITEF standard for doing strong encrypted authentication in network based applications. OPENssh uses this API and the underlying kerberos 5 code to provide a alternative means of authentication other than ssh_keys.
The GSSAPI, by itself, does not provide any security. Instead, security service vendors provide GSSAPI implementations usually in the form of libraries installed with their security software.


1. Open Putty.
2. Go to Connection->SSH->Auth->GSSAPI.
3. Uncheck the "Attempt GSSAPI authentication(SSH2-only)" option.
4. Save the session.

Putty: Access Denied Problem

Note: PuTTY 0.62 fixed the bug where failing GSSAPI authentication caused this error message.


Saturday, June 30, 2012

Ubuntu 12.04 : Middle Click Shortcut

Using Mouse:
1.  Usually Mouse has a scroll wheel, click it to use it as middle click.
2.  Some old mouse has middle click instead of scroll wheel.

Using Touch-pad:

1. On touchpads that support multi-finger taps, you can tap with three fingers at once to middle-click.
    Note: This feature is not available in all laptops. My laptop doesn't have this functionality.


1. "Paste Selected Text" inside applications. Select the text as normal, then bring your mouse(without deselecting) where you want to paste it, and finally use middle click to paste it. Some of the applications that I have tested till now are: gedit, chrome, terminal, gnote.
Note: Pasting text with your middle mouse button is completely separate from the normal clipboard. Selecting text does not copy it to your clipboard.

2. In the "file manager", middle-click serves two roles. If you middle-click a folder, it will open in a new tab. This mimics the behavior of popular web browsers. If you middle-click a file, it will open the file, just as if you had double-clicked.

3. Most "web browsers" allow you to open links in tabs quickly with the middle mouse button. Just click any link with your middle mouse button, and it will open in a new tab.

4. On "scrollbars and sliders", a regular click in the empty space moves by a set amount (such as one page) in the direction you clicked. You can also middle-click in the empty space to move to exactly the location you clicked.



Sunday, May 6, 2012

Recover Login Password of Ubuntu 12.04

After my first installation of Ubuntu 12.04, I forgot my login password and need to recover it.

To recover it you need to follow these steps:

1. Boot your computer.

2. When you get the grub menu, select option with recover as shown in figure.

Ubuntu 12.04 : Grub Menu
3. This will take you to recovery menu. In recovery menu select option "drop to root shell" as shown in figure.

Ubuntu 12.04 : Recovery Menu

4. A shell prompt will be displayed at the bottom of the screen with root as username. To change the password of particular user say naveen

       passwd naveen

5. The above command will ask you to enter your new password and retype password. Type your new password.

6. You might get "Authentication Manipulation error". If you get this error then you need to type :
     mount -rw -o remount /
    And again follow step 4 and 5.

Saturday, May 5, 2012

Ubuntu 12.04 : Adding Bookmarks/Shortcuts to left sidebar of nautilus manager

If you are looking for adding folder shortcuts/ bookmarks to the left sidebar of Nautilus Manger (folder explorer), then you have come to the right place. The image below shows the finally added bookmarks.

Ubuntu 12.04: Nautilus Sidebar Bookmarks

In Ubuntu 12.04, you cannot directly Drag and Drop folder to the sidebar. This problem occurs only for the first bookmark. If you have added the first bookmark, then you can Drag and Drop elements.

To add your first bookmark:

1. Go to your folder and press Ctrl + D (or ADD from Bookmark option in menu bar).

This will add your first bookmark as shown below. In my case the folder was example-content.

2. Now you can Drag and Drop your folder into the Bookmarks.

Ubuntu 12.04 : Keyboard Shortcut List

Ubuntu 12.04 has come up with a new way to display some common Unity Desktop keyboard shortcuts.

If you hold 'super' key for 2 seconds, you can see a Lens coming up displaying Ubuntu Desktop Keyboard shortcut keys. The image below shows the Shortcut Lens.

Ubuntu 12.04 : Keyboard Shortcut Keys

You can find comprehensive list of keyboard shortcuts of various Ubuntu 12.04 default applications here:

Sunday, January 29, 2012

How to run Ubuntu inside Windows using Virtual Machine

What is Virtual Machine?
A virtual machine (VM) is a "completely isolated guest operating system installation within a normal host operating system".They allow  you to run one operating system emulated within another operating system. 
In this case :
Guest Operating System: Ubuntu 11.04
Host Operating System : Windows 7

Some of the popular Virtual Machine:

1. VirtualBox (Windows/Mac/Linux, Free): VirtualBox has a loyal following thanks to a combination of a free-as-in-beer price tag, cross-platform support, and a huge number of features that make running and maintaining virtual machines a breeze.
Read More:

2.  Parallels (Windows/Mac/Linux, $79.99): Although best known for the Mac version of their virtual machine software, Parallels also runs virtualization on Windows and Linux.
Read More:

3. Windows Virtual PC(Windows, Free): Compared to the other any-OS-under-the-sun virtual machine applications in this week's Hive Five, Windows Virtual PC is a tame offering. Windows Virtual PC exists solely to emulate other—usually earlier—versions of Windows. If you need to run an app that only works under Windows XP or test software for backwards compatibility with Vista, Windows Virtual Machine has you covered. It's limited, true, but for people working in a strictly Windows environment —and most of the world still is—it gets the job done. Note: Virtual PC is availabls as Virtual PC 2004, Virtual PC 2007, and Windows Virtual PC
Read More :

4. QEMU (Linux, Free) : QEMU is a powerful virtualization tool for Linux machines built upon the back of the KVM system (Kernel-based Virtual Machine).
Read More:

5. VMware (Windows/Linux, Basic: Free, Premium: $189):  VMware for desktop users comes in two primary flavors: VMware Player and VMware Workstation. VMware Player is a free solution aimed at casual users who need to create and run virtual machines but don't need advanced enterprise-level solutions. VMware Workstation includes all the features of VMWare Player—easy virtual machine creation, hardware optimization, driver-less guest OS printing—and adds in the ability to clone machines, take multiple snapshots of the guest OS, and a replay changes made to the guest OS for testing software and recording the results within the virtual machine. You can read more about VMware Player here and VMware Workstation here.
Read More:

How to Run Ubuntu on Virtual Machine ?

Guest Operating System : Ubuntu 11.04
Host Operarting System : Windows 7

1. Download the ISO file of Ubuntu 11.04 from
2. Download the VirtualBox Sofware for the appropriate Host OS. In our case host operating System: Windows 7