Oracle VM VirtualBox

Welcome to Oracle VM VirtualBox..!!

VirtualBox is a cross-platform virtualization application. What does that mean? For one thing, it installs on your existing Intel or AMD-based computers, whether they are running Windows, Mac, Linux or Solaris operating systems. Secondly, it extends the capabilities of your existing computer so that it can run multiple operating systems (inside multiple virtual machines) at the same time. So, for example, you can run Windows and Linux on your Mac, run Windows Server 2008 on your Linux server, run Linux on your Windows PC, and so on, all alongside your existing applications. You can install and run as many virtual machines as you like -- the only practical limits are disk space and memory.

VirtualBox is deceptively simple yet also very powerful. It can run everywhere from small embedded systems or desktop class machines all the way up to datacenter deployments and even Cloud environments. just see Right side picture.

      Why is Virtualization useful??

      The techniques and features that VirtualBox provides are useful for several scenarios:

Ø  Running multiple operating systems simultaneously. VirtualBox allows you to run more than one operating system at a time. This way, you can run software written for one operating system on another without having to reboot to use it. Since you can configure what kinds of "virtual" hardware should be presented to each such operating system, you can install an old operating system such as DOS or OS/2 even if your real computer's hardware is no longer supported by that operating system.

Ø  Easier software installations. Software vendors can use virtual machines to ship entire software configurations. For example, installing a complete mail server solution on a real machine can be a tedious task. With VirtualBox, such a complex setup (then often called an "appliance") can be packed into a virtual machine. Installing and running a mail server becomes as easy as importing such an appliance into VirtualBox.

Ø  Testing and disaster recovery. Once installed, a virtual machine and its virtual hard disks can be considered a "container" that can be arbitrarily frozen, woken up, copied, backed up, and transported between hosts.

On top of that, with the use of another VirtualBox feature called "snapshots", one can save a particular state of a virtual machine and revert back to that state, if necessary. This way, one can freely experiment with a computing environment. If something goes wrong (e.g. after installing misbehaving software or infecting the guest with a virus), one can easily switch back to a previous snapshot and avoid the need of frequent backups and restores.

Any number of snapshots can be created, allowing you to travel back and forward in virtual machine time. You can delete snapshots while a VM is running to reclaim disk space.

Ø  Infrastructure consolidation. Virtualization can significantly reduce hardware and electricity costs. Most of the time, computers today only use a fraction of their potential power and run with low average system loads. A lot of hardware resources as well as electricity is thereby wasted. So, instead of running many such physical computers that are only partially used, one can pack many virtual machines onto a few powerful hosts and balance the loads between them.

Features Overview

Ø  Portability- VirtualBox runs on a large number of 32-bit and 64-bit host operating systems

VirtualBox is a so-called "hosted" hypervisor (sometimes referred to as a "type 2" hypervisor). Whereas a "bare-metal" or "type 1" hypervisor would run directly on the hardware, VirtualBox requires an existing operating system to be installed. It can thus run alongside existing applications on that host.

To a very large degree, VirtualBox is functionally identical on all of the host platforms, and the same file and image formats are used. This allows you to run virtual machines created on one host on another host with a different host operating system; for example, you can create a virtual machine on Windows and then run it under Linux.

In addition, virtual machines can easily be imported and exported using the Open Virtualization Format an industry standard created for this purpose. You can even import OVFs that were created with a different virtualization software.

Ø  No hardware virtualization required- For many scenarios, VirtualBox does not require the processor features built into newer hardware like Intel VT-x or AMD-V. As opposed to many other virtualization solutions, you can therefore use VirtualBox even on older hardware where these features are not present.

Ø  Guest Additions: shared folders, seamless windows, 3D virtualization- The VirtualBox Guest Additions are software packages which can be installed inside of supported guest systems to improve their performance and to provide additional integration and communication with the host system. After installing the Guest Additions, a virtual machine will support automatic adjustment of video resolutions, seamless windows, accelerated 3D graphics and more.

Ø  Great hardware support- Among others, VirtualBox supports:

o    Guest multiprocessing (SMP)- VirtualBox can present up to 32 virtual CPUs to each virtual machine, irrespective of how many CPU cores are physically present on your host.

o    USB device support- VirtualBox implements a virtual USB controller and allows you to connect arbitrary USB devices to your virtual machines without having to install device-specific drivers on the host. USB support is not limited to certain device categories.

o    Hardware compatibility- VirtualBox virtualizes a vast array of virtual devices, among them many devices that are typically provided by other virtualization platforms. That includes IDE, SCSI and SATA hard disk controllers, several virtual network cards and sound cards, virtual serial and parallel ports and an Input/Output Advanced Programmable Interrupt Controller (I/O APIC), which is found in many modern PC systems. This eases cloning of PC images from real machines and importing of third-party virtual machines into VirtualBox.

o    Full ACPI support- The Advanced Configuration and Power Interface (ACPI) is fully supported by VirtualBox. This eases cloning of PC images from real machines or third-party virtual machines into VirtualBox. With its unique ACPI power status support, VirtualBox can even report to ACPI-aware guest operating systems the power status of the host. For mobile systems running on battery, the guest can thus enable energy saving and notify the user of the remaining power (e.g. in fullscreen modes).

o    Multiscreen resolutions- VirtualBox virtual machines support screen resolutions many times that of a physical screen, allowing them to be spread over a large number of screens attached to the host system.

o    Built-in iSCSI support- This unique feature allows you to connect a virtual machine directly to an iSCSI storage server without going through the host system. The VM accesses the iSCSI target directly without the extra overhead that is required for virtualizing hard disks in container files.

o    PXE Network boot- The integrated virtual network cards of VirtualBox fully support remote booting via the Preboot Execution Environment (PXE).

Ø  Multigeneration branched snapshots- VirtualBox can save arbitrary snapshots of the state of the virtual machine. You can go back in time and revert the virtual machine to any such snapshot and start an alternative VM configuration from there, effectively creating a whole snapshot tree. create and delete snapshots while the virtual machine is running.

Ø  Clean architecture; unprecedented modularity- VirtualBox has an extremely modular design with well-defined internal programming interfaces and a clean separation of client and server code. This makes it easy to control it from several interfaces at once: for example, you can start a VM simply by clicking on a button in the VirtualBox graphical user interface and then control that machine from the command line, or even remotely.

 Due to its modular architecture VirtualBox can also expose its full functionality and configurability through a comprehensive software development kit (SDK), which allows for integrating every aspect of VirtualBox with other software systems.

Ø   Remote machine display- The VirtualBox Remote Desktop Extension (VRDE) allows for high-performance remote access to any running virtual machine. This extension supports the Remote Desktop Protocol (RDP) originally built into Microsoft Windows, with special additions for full client USB support.

The VRDE does not rely on the RDP server that is built into Microsoft Windows; instead, it is plugged directly into the virtualization layer. As a result, it works with guest operating systems other than Windows (even in text mode) and does not require application support in the virtual machine either.

On top of this special capacity, VirtualBox offers you more unique features:

o    Extensible RDP authentication- VirtualBox already supports Winlogon on Windows and PAM on Linux for RDP authentication. In addition, it includes an easy-to-use SDK which allows you to create arbitrary interfaces for other methods of authentication.

o    USB over RDP- Via RDP virtual channel support, VirtualBox also allows you to connect arbitrary USB devices locally to a virtual machine which is running remotely on a VirtualBox RDP server.

Supported host Operating system

Ø  Windows hosts:

    Windows XP, all service packs (32-bit)

    Windows Server 2003 (32-bit)

    Windows Vista (32-bit and 64-bit)

    Windows Server 2008 (32-bit and 64-bit)

    Windows 7 (32-bit and 64-bit)

Ø  Mac OS X hosts:

    10.5 (Leopard, 32-bit)

    10.6 (Snow Leopard, 32-bit and 64-bit)

Ø  Linux hosts (32-bit and 64-bit). Among others, this includes:

    Ubuntu 6.06 ("Dapper Drake"), 6.10 ("Edgy Eft"), 7.04 ("Feisty Fawn"), 7.10 ("Gutsy Gibbon"), 8.04 ("Hardy Heron"), 8.10 ("Intrepid Ibex"), 9.04 ("Jaunty Jackalope"), 9.10 ("Karmic Koala"), 10.04 ("Lucid Lynx"), 10.10 ("Maverick Meerkat).

    Debian GNU/Linux 3.1 ("sarge"), 4.0 ("etch"), 5.0 ("lenny") and 6.0 ("squeeze")

    Oracle Enterprise Linux 4 and 5

    Redhat Enterprise Linux 4, 5 and 6

    Fedora Core 4 to 14

    Gentoo Linux

    SUSE Linux 9, 10 and 11, openSUSE 10.3, 11.0, 11.1, 11.2, 11.3

    Mandriva 2007.1, 2008.0, 2009.1, 2010.0 and 2010.1

It should be possible to use VirtualBox on most systems based on Linux kernel 2.6 using either the VirtualBox installer or by doing a manual installation.However, the formally tested and supported Linux distributions are those for which we offer a dedicated package.

Note that starting with VirtualBox 2.1, Linux 2.4-based host operating systems are no longer supported.

Ø  Solaris hosts (32-bit and 64-bit) are supported

               Solaris 11 Express (Nevada build 86 and higher, OpenSolaris 2008.05 and higher)

               Solaris 10 (u8 and higher)

But with the restrictions below:

ü  There is no support for USB devices connected to Solaris 10 hosts.

ü  USB support on Solaris hosts requires kernel version snv_124 or higher. Webcams and other isochronous devices are known to have poor performance.

ü  No ACPI information (battery status, power source) is reported to the guest.

ü  No support for using wireless adapters with bridged networking.

Cloud Computing

Cloud computing is a model for enabling convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction.

Cloud computing is a general term for anything that involves delivering hosted services over the Internet. These services are broadly divided into three categories: Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS) and Software-as-a-Service (SaaS). The name cloud computing was inspired by the cloud symbol that's often used to represent the Internet in flowcharts and diagrams.

A cloud service has three distinct characteristics that differentiate it from traditional hosting. It is sold on demand, typically by the minute or the hour; it is elastic -- a user can have as much or as little of a service as they want at any given time; and the service is fully managed by the provider (the consumer needs nothing but a personal computer and Internet access). Significant innovations in virtualization and distributed computing, as well as improved access to high-speed Internet and a weak economy, have accelerated interest in cloud computing.

How it works?

When a user accesses the cloud for a popular website, many things can happen. The user's IP for example can be used to establish where the user is located. DNS services can then direct the user to a cluster of servers that are close to the user so the site can be accessed rapidly and in their local language. The user doesn't login to a server, but they login to the service they are using by obtaining a session id and/or a cookie which is stored in their browser.

What the user sees in the browser will usually come from a cluster of web servers. The webservers run software which presents the user with an interface which is used to collect commands or instructions from the user (the clicks, typing, uploads etc.) These commands are then interpreted by webservers or processed by application servers. Information is then stored on or retrieved from the database servers or file servers and the user is then presented with an updated page. The data across the multiple servers is synchronised around the world for rapid global access .

What are you interested in learning more about?

a.     Building a private cloud

b.     Using the cloud for development and testing

c.     Security and the cloud

d.     Understanding cloud computing pricing

A cloud can be private or public. A public cloud sells services to anyone on the Internet. (Currently, Amazon Web Services is the largest public cloud provider.) A private cloud is a proprietary network or a data center that supplies hosted services to a limited number of people. When a service provider uses public cloud resources to create their private cloud, the result is called a virtual private cloud. Private or public, the goal of cloud computing is to provide easy, scalable access to computing resources and IT services.

Infrastructure-as-a-Service like Amazon Web Services provides virtual server instance API to start, stop, access and configure their virtual servers and storage. In the enterprise, cloud computing allows a company to pay for only as much capacity as is needed, and bring more online as soon as required. Because this pay-for-what-you-use model resembles the way electricity, fuel and water are consumed, it's sometimes referred to as utility computing.

Platform-as-a-service in the cloud is defined as a set of software and product development tools hosted on the provider's infrastructure. Developers create applications on the provider's platform over the Internet. PaaS providers may use APIs, website portals or gateway software installed on the customer's computer. Force.com, (an outgrowth of Salesforce.com) and GoogleApps are examples of PaaS. Developers need to know that currently, there are not standards for interoperability or data portability in the cloud. Some providers will not allow software created by their customers to be moved off the provider's platform.

In the software-as-a-service cloud model, the vendor supplies the hardware infrastructure, the software product and interacts with the user through a front-end portal. SaaS is a very broad market. Services can be anything from Web-based email to inventory control and database processing. Because the service provider hosts both the application and the data, the end user is free to use the service from anywhere.

CAPTCHA: Telling Humans and Computers Apart Automatically

A CAPTCHA is a program that protects websites against bots by generating and grading tests that humans can pass but current computer programs cannot. This has the benefit of distinguishing humans from computers. It also creates incentive to further develop artificial intelligence of computers.

The term "CAPTCHA" was coined in 2000 by Luis Von Ahn, Manuel Blum, Nicholas J. Hopper, and John Langford (all of Carnegie Mellon University). It is a contrived acronym based on the word "capture" and standing for "Completely Automated Public Turing test to tell Computers and Humans Apart". Carnegie Mellon University attempted to trademark the term, but the trademark application was abandoned on 21 April 2008.

Applications

CAPTCHAs are used in attempts to prevent automated software from performing actions which degrade the quality of service of a given system, whether due to abuse or resource expenditure. CAPTCHAs can be deployed to protect systems vulnerable to e-mail spam, such as the webmail services of Gmail, Hotmail, and Yahoo Mail.

CAPTCHAs are also used to minimize automated posting to Blogs, forums and wikis. whether as a result of commercial promotion or harassment and vandalism. CAPTCHAs also serve an important function in rate limiting. Automated usage of a service might be desirable until such usage is done to excess and to the detriment of human users. In such cases, administrators can use CAPTCHA to enforce automated usage policies based on given thresholds.

As of 2010, most CAPTCHAs display distorted text that is difficult to read by character recognition software. The alternative implementations may include various tests, such as identifying an object that does not belong in a particular set of objects, locating the center of a distorted image, or identifying distorted shapes.

Accessibility

CAPTCHAs rely on visual perception, users unable to view a CAPTCHA due to a disability will be unable to perform the task protected by a CAPTCHA. Therefore, sites implementing CAPTCHAs may provide an audio version of the CAPTCHA in addition to the visual method. The official CAPTCHA site recommends providing an audio CAPTCHA for accessibility reasons, but it is not usable for deafblind people or for users of text web browsers. This combination is not universally adopted, with most websites (including Wikipedia) offering only the visual CAPTCHA, with or without providing the option of generating a new image if one is too difficult to read.

Use reCAPTCHA on Your Site

reCAPTCHA helps prevent automated abuse of your site (such as comment spam or bogus registrations) by using a CAPTCHA  to ensure that only humans perform certain actions.

• It's Free! Yep, reCAPTCHA is free.
• It's Useful. Why waste the effort of your users? reCAPTCHA helps to digitize books.
• It's Accessible. reCAPTCHA has an audio test that allows blind people to freely navigate your site.
• It's Secure. Most other CAPTCHA implementations can be easily broken.
• It's Popular. Over 100,000 sites use reCAPTCHA, including household names like Facebook, Ticketmaster, and Craigslist.
• It's Easy. reCAPTCHA is a Web service. As such, adopting it is as simple as adding a few lines of code on your site. For many applications and programming languages such as Wordpress and PHP we also have easy-to-install plugins available. We generate and check the distorted images, so you don't need to run costly image generation programs.

Captcha Fun: Guess Appropriate word from Pictures and write it in Answer Box.

http://server251.theory.cs.cmu.edu/cgi-bin/esp-pix/post-query-pix-esp