1. Linux1.1 Introduction to Linux

Linux is a Unix-like and mostly POSIX-compliant computer operating system assembled under the model of free and open source software development and distribution. The defining component of Linux is the Linux kernel, an operating system kernel first released on 5 October 1991 by Linux Torvalds.

Linux was originally developed as a free operating system for Intel x86-based personal computers. It has since been ported to more computer hardware platforms than any other operating system.] It is a leading operating system on servers and other big iron systems such as mainframe computers and supercomputers. As of June 2013, more than 95% of the world's 500 fastest supercomputers run some variant of Linux, including all the 44 fastest.

Linux also runs on embedded systems, which are devices whose operating system is typically built into the firmware and is highly tailored to the system; this includes mobile phones, tablet computers, network routers, facility automation controls, televisions and video game consoles. Android, which is a widely used operating system for mobile devices, is built on top of the Linux kernel.

1.2 History

The history of Linux began with UNIX in 1969. UNIX was created at Bell Labs with the goals: Simplicity, Recyclable code, written in C as opposed to assembly. Development started in 1991. Linux Torvalds wanted to create a free implementation of UNIX. By 1993 there were 12000 Linux users. Today Linux rivals UNIX in stability and scalability.

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1.3 Linux Architecture

Linux System Architecture is consists of following layers

Hardware layer - Hardware consists of all peripheral devices (RAM/ HDD/ CPU etc).

Kernel - Kernel is the core part of Linux. It is responsible for all major activities of this operating system. It is consists of various modules and it interacts directly with the underlying hardware. Kernel provides the required abstraction to hide low level hardware details to system or application programs. Core component of Operating System, interacts directly with hardware, and provides low level services to upper layer components.

Figure.1.1 Linux System Architecture

Shell - An interface to kernel, hiding complexity of kernel's functions from users. Takes commands from user and executes kernel's functions.

Utilities - Utility programs giving user most of the functionalities of an operating systems.

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1.4 Features

Multitasking: several programs running at the same time.

Multiuser: several users on the same machine at the same time (and no two-user licenses!).

Multiplatform: runs on many different CPUs, not just Intel.

Multiprocessor: SMP support is available on the Intel and SPARC platforms (with work currently in progress on other platforms), and Linux is used in several loosely-coupled MP applications, including Beowulf systems and the Fujitsu AP1000+ SPARC-based supercomputer.

Multithreading: has native kernel support for multiple independent threads of control within a single process memory space.

Runs in protected mode on the 386.

Has memory protection between processes, so that one program can't bring the whole system down.

Demand loads executable: Linux only reads from disk those parts of a program that are actually used.

Shared copy-on-write pages among executables. This means that multiple processes can use the same memory to run in. When one tries to write to that memory, that page (4KB piece of memory) is copied somewhere else. Copy-on-write has two benefits: increasing speed and decreasing memory use.

Virtual memory using paging (not swapping whole processes) to disk: to a separate partition or a file in the file system, or both, with the possibility of adding more swapping areas during runtime (yes, they're still called swapping areas). A total of 16 of these 128 MB (2GB in recent kernels) swapping areas can be used at the same time, for a theoretical total of 2 GB of useable swap space. It is simple to increase this if necessary, by changing a few lines of source code.

A unified memory pool for user programs and disk cache, so that all free memory can be used for caching, and the cache can be reduced when running large programs.

Dynamically linked shared libraries (DLL’s) and static libraries too, of course.

Does core dumps for post-mortem analysis, allowing the use of a debugger on a program not only while it is running but also after it has crashed.

Mostly compatible with POSIX, System V, and BSD at the source level.

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Through an iBCS2-compliant emulation module, mostly compatible with SCO, SVR3, and SVR4 at the binary level.

All source code is available, including the whole kernel and all drivers, the development tools and all user programs; also, all of it is freely distributable. Plenty of commercial programs are being provided for Linux without source, but everything that has been free, including the entire base operating system, is still free.

POSIX job control.

Pseudo terminals (pty's).

387-emulation in the kernel so that programs don't need to do their own math emulation. Every computer running Linux appears to have a math coprocessor. Of course, if your computer already contains an FPU, it will be used instead of the emulation, and you can even compile your own kernel with math emulation removed, for a small memory gain.

Support for many national or customized keyboards, and it is fairly easy to add new ones dynamically.

Multiple virtual consoles: several independent login sessions through the console, you switch by pressing a hot-key combination (not dependent on video hardware). These are dynamically allocated; you can use up to 64.

Supports several common file systems, including minix, Xenix, and all the common system V file systems, and has an advanced filesystems of its own, which offers file systems of up to 4 TB, and names up to 255 characters long.

Transparent access to MS-DOS partitions (or OS/2 FAT partitions) via a special filesystems: you don't need any special commands to use the MS-DOS partition, it looks just like a normal Unix filesystems (except for funny restrictions on filenames, permissions, and so on). MS-DOS 6 compressed partitions do not work at this time without a patch (dmsdosfs). VFAT (WNT, Windows 95) support and FAT-32 is available in Linux 2.0

Special filesystems called UMSDOS which allows Linux to be installed on a DOS filesystems.

read-only HPFS-2 support for OS/2 2.1

HFS (Macintosh) file system support is available separately as a module.

CD-ROM filesystem which reads all standard formats of CD-ROMs.

TCP/IP networking, including ftp, telnet, NFS, etc.

Appletalk server

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Netware client and server

Lan Manager/Windows Native (SMB) client and server

Many networking protocols: the base protocols available in the latest development kernels include TCP, IPv4, IPv6, AX.25, X.25, IPX, DDP (Appletalk), Netrom, and others. Stable network protocols included in the stable kernels currently include TCP, IPv4, IPX, DDP, and AX.25

1.5 Windows vs. Linux

Table 1.Windows vs. Linux

Linux Windows

What is it?

Linux is an example of Open Source software development and Free Operating System (OS).

Windows is the family of operating system (OS) from Microsoft, which is the most famous OS in the world.

Cost

Linux can be freely distributed, downloaded freely, distributed through magazines, Books etc. There are priced versions for Linux also, but they are normally cheaper than Windows.

For desktop or home use, Windows can be expensive. A single copy can cost around $50 to $ 450 depending on the version of Windows.

UserEveryone. From home users to developers and computer enthusiasts alike.

Everyone. From home users to developers and computer enthusiasts alike.

Manufacturer

Linux kernel is developed by the community. Linux Torvalds oversees things.

Microsoft created the Windows operating system, but allows other computer manufactures to distribute their own computers with Windows pre-installed.

Usage

Linux can be installed on a wide variety of computer hardware, ranging from mobile phones, tablet computers and video game consoles, to mainframes and supercomputers.

On PC's desktops, laptops, servers and some phones.

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Development and

Distribution

Linux is developed by Open Source development i.e. through sharing and collaboration of code and features through forums etc and it is distributed by various vendors.

Windows is developed and distributed by Microsoft.

GUI

Linux typically provides two GUIs, KDE and Gnome. But there are millions of alternatives such as LXDE, Xfce, Unity, Mate, twm, ect.

The Windows GUI is an integral component of the OS and is not replaceable. This can be a con when it comes to Windows 8's Metro.

File system support

Ext2, Ext3, Ext4, Jfs, ReiserFS, Xfs, Btrfs, FAT, FAT32, NTFS

FAT, FAT32, NTFS, exFAT

Text mode interface

BASH (Bourne Again Shell) is the Linux default shell. It can support multiple command interpreters.

Windows uses a command shell and each version of Windows has a single command interpreter with dos-like commands, recently there is the addition of the optional Power Shell that uses more Unix-like commands.

PriceFree but support is available for a price.

$50-$450

Security

Linux has had about 60-100 viruses listed till date. None of them actively spreading nowadays.

According to Dr.Nic Peeling and Dr Julian Satchell's “Analysis of the Impact of Open Source Software” there have been more than 60,000 viruses in Windows. Anti Virus cost about $20 to $400

Threat detection and

solution

In case of Linux, threat detection and solution is very fast, as Linux is mainly community driven and whenever any Linux user posts any kind of threat, several developers start working on it from different parts of the world

After detecting a major threat in Windows OS, Microsoft generally releases a patch that can fix the problem and it can take more than 2/3 months. Sometimes sooner, Microsoft releases patches and updates weekly.

Processors Dozens of different kinds. Limited but most (80%)

ExamplesUbuntu, Fedora, Red Hat, Debian, Archlinux, Android etc.

Windows 8, 8.1, 7, Vista, XP

Gaming

Very few games available natively. Some games can be played through Wine, but often not all features are available.

Almost all games are compatible with Windows. Some CPU intensive and graphics intensive games are exclusive to Windows PC's.

User Although there are many GUI Everything can be controlled

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experience

applications, most of the work is done through Terminal (a console window), and if a problem arrises GUI is rarely usable to fix them.

through GUI and incompatibility problems are rare.

Graphics performance

Because hardware manufacturers, such as NVidia, often do not provide documentation for Linux developers, drivers cannot use full card performance.

Combined with newest DirectX versions and full graphics card support the performance is almost as good as it can get.

Company / developer

Linux Torvalds Microsoft

Introduction (from

Wikipedia)

Linux is a Unix-like and POSIX-compliant computer operating system assembled under the model of free and open source software development and distribution. The defining component of Linux is the Linux kernel, an operating system kernel first released

Microsoft Windows is a series of graphical interface operating systems developed, marketed, and sold by Microsoft. Microsoft introduced an operating environment named Windows on November 20, 1985 as a graphical operating system shell for MS-DOS.

Available language(s)

Multilingual Multilingual

License GNU/Free Proprietary

Supported platforms

All PowerPC: versions 1.0 - NT 4.0; DEC Alpha: versions 1.0 - NT 4.0; MIPS R4000: versions 1.0 - NT 4.0; IA-32: versions 1.0 - 8; IA-64: version XP; x86-64: versions XP - 8; ARM: version RT;

Default user interface

Gnome or KDE (Depends on distro)

Graphical (Windows Aero)

Preceded by Basic Terminal (CLI) MS-DOSSource model Open Source Closed / Shared source

Update method

Many Windows Update

Terminal Multi Terminal Windows --

1.6 Distributors of Linux

Ubuntu

Mint

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Fedora

Debian

Red HatEtc.

1.7 Red Hat Enterprise Linux

Red Hat, Inc. is an American multinational software company providing open-source software products to the enterprise community. Founded in 1993, Red Hat has its corporate headquarters in Raleigh, North Carolina, with satellite offices worldwide.

Red Hat has become associated to a large extent with its enterprise operating system Red Hat Enterprise Linux and with the acquisition of open-source enterprise middleware vendor JBoss. Red Hat provides operating system platforms, middleware, applications, management products, and support, training, and consulting services. Red Hat creates, maintains, and contributes to many free software projects and has also acquired several proprietary software packages and released their source code mostly under the GNU GPL while holding copyright under a single commercial entity and selling user subscriptions. As of June 2013, Red Hat is the largest corporate contributor to Linux.

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2.YUM Server

1.1.What is YUM?

Yum or Yellow dog Update, Modified is a package manager that was developed by Duke University to improve the installation of RPMs.Yum searches numerous repositories for packages and their dependencies so they may be installed together in an effort to alleviate dependency issues. Red Hat Enterprise Linux 5 uses Yum to fetch packages and install RPMs.Yum uses a configuration file at /etc/yum.conf.There are multiple ways by which you can install a repository on the system and install/update packages:

1. Add an existing repository.2. Setup a new repository having packages populated from ISO's

downloaded from RHN.

3. Register the system on RHN and subscribed to the channels depending on the subscription you have.

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1.2.How to Create YUM Server.

Step 1: Make a directory at /var/ftp/pub

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Figure 2.1Making a directory

This Directory is made for copying all the packages from installation disk to packages folder. It is done so that we don’t have to mount the CD again and again.

Step 2: Mount cd

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Figure. 2.2 Mounting CD

Here it is shown that the CD is successfully mounted and we can access the data inside it.

We change the directory to /mnt to proceed to copy the packages.

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Step 3: Copy Packages from /mnt/Packages to /var/ftp/pub

Figure. 2.3 Copying Packages

Cp is used to copy one or more files to another location. Here we are copying the packages form Packages folder to /var/ftp/pub

Note :1. From second cd too Server content in to our /var/ftp/pub/Packages/ folder as shown below.2. Here please take destination folder as /var/ftp/pub so that we can implement FTP server to share our repository.3. If you have RHEL5 DVD then execute below command once.

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Figure. 2.4 Packages being copied

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Step 4: Install the packages vsftpd, deltarpm, python-deltarpm and createrepo.

Figure. 2.5 Installing the required Packages

In this step, we change the directory to /var/ftp/pub/Packages and install the all those package that are required to run the YUM server and remove the dependency problem.

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Step 5: Open file test.repo .

Figure. 2.6 Opening Repository

Now, we create a repository to save the server information that we are going to create.

Note : The directory /etc/yum.repos.d/ contains two .repo files which should be removed or moved to other directory, so that YUM server will check default .repo file itself. Q. What if I don't move or remove the default .repo files from /etc/yum.repos.d/ folder? A: Every time when you try to install packages through YUM, your yum will check all these files for repositories for getting packages which will or will not work and most probably delay is increased in getting those packages from online servers.

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Step 6: Enter the following in test.repo

Figure. 2.7 Entering Server Information

The new file which is created contains as follows.

[server]

name=myrepobaseurl=file:///var/ftp/pub/Packagesgpgcheck=0

After entering these entries save and exit from the file.

[server1.example.com] ==>This informs what is the repository name.

baseurl ==> This is the server and path of the repo(here it’s a local repo so the base url is just a file:///gpgcheck ==> This is to check the authentication of the repository, which is disabled in this case.

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Step 7: Restart vsftpd service.

Figure. 2.8 Restarting vsftpd service

Vsftpd is restarted whenever we edit repositories so that they are updated.

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Step 8: Update the repositories.

Figure. 2.9 Repositories Updated

Note: In-order to use yum repository we have to clean the yum meta data, so before installing any package first time use yum clean all command as shown above.

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Step 9: Use “yum list all” to check the repositories data.

Figure. 2.10 Showing Repositories Data

YUM server has been created and its content is shown with yum list all command.

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3.WEB Server

1.3. What is HTTP and HTTP Server?

The Hypertext Transfer Protocol (HTTP) is an application protocol for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web.

Hypertext is structured text that uses logical links (hyperlinks) between nodes containing text. HTTP is the protocol to exchange or transfer hypertext.

The Apache HTTP Server commonly referred to as Apache, is a web server application notable for playing a key role in the initial growth of the World Wide Web. Originally based on the NCSA HTTPd server, development of Apache began in early 1995 after work on the NCSA code stalled. Apache quickly overtook NCSA HTTPd as the dominant HTTP server, and has remained the most popular HTTP server in use since April 1996. In 2009, it became the first web server software to serve more than 100 million websites.

Apache is developed and maintained by an open community of developers under the auspices of the Apache Software Foundation. Most commonly used on a Unix-like system, the software is available for a wide variety of operating systems, including Unix, FreeBSD, Linux, Solaris, Novell NetWare, OS X, Microsoft Windows, OS/2, TPF, OpenVMS and eComStation. Released under the Apache License, Apache is open-source software.

1.4. Requirements

YUM server, HTTP rpm.

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1.5. Creation of Apache HTTP server

Step 1: Check whether http is installed or not.

Figure.3.1Checking http files

In this step, we have to check whether the rpm packages of http are installed or not. For checking this we use the command “rpm –qa | grep http”. If the packages are installed it will show them in the result, if the packages are not installed we install them with the help of YUM server, using command “yum install http* -y”.

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Step 2: Edit the httpd configuration file.

Figure.3.2Editng http Configuration

httpd.conf file contains the configuration settings for the Apache server.

Edit the httpd.conf file using your vi editor using the vi command. Once loaded, there are a number of settings that need to be changed to match our environment.

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Step 3: Enter the server information as shown below.

Figure3.3 Entering Server Information

The ServerAdmin directive defines an administrative email address for people wishing to contact the root for your site,

Next the ServerName and ServerAlias directives need to be defined so that the web server knows which virtual host this configuration file refers to.

we need to define where the web site files are going to be located using the Document Root directive. The tradition is to use /var/www/html

Save and quit the file.

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Step 4: Check for errors in configuration file.

Figure 3.4Checking Errors

http –t command is used to check whether there is any syntax error in httpd.conf file or not.

If there aren’t any errors in the above mentioned file “Syntax OK” message will be displayed.

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Step 5: Restart httpd service.

Figure3.5Restartinghttpd service

httpd is restarted whenever we edit repositories related to that service so that they are updated.

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Step 6: Create a html file in /var/www/html .

Figure 3.6Creating html file

Here, malala.html is the new html file created.

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Step 7: Write the message to be displayed in malala.html .

Figure 3.7Editing html file

In this file, we are supposed to write html coding or just a simple message to be displayed.

Save file and exit.

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Step 8: Now, edit the host file and enter the IP address of server, host name and server name after removing anything that was previously written.

Figure.3.8 Host file data

IP address: - 192.168.1.1

Host Name: - ashubh

Server Name: - impulseyouth.com

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Step 9: Restart httpd service.

httpd is restarted whenever we edit repositories related to that service so that they are updated.

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Step 10: Now open firefox and type your server name in the url bar.

Figure.3.9 Firefox

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1.6.Indexing on webpage

Step 1: Create a directory in /var/www/html/

Figure.3.10Creating song directory

This directory is created to save the files that we are going to host on download page.

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Step 2: Create some files in song directory.

Figure.3.11Creating files in song

We are using mp3 files as downloading files. Here we are creating some mp3 files that will be used as downloading files.

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Step 3: Open httpd configuration file.

Figure.3.12Editing http configuration

httpd.conf file contains the configuration settings for the Apache server.

Edit the httpd.conf file using your vi editor using the vi command. Once loaded, there are a number of settings that need to be changed to match our environment.

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Step 4: Add the directory information and path as shown below.

Figure.3.13Adding server data

The Directory Index directive allows you to specify a document to be served to a client when a directory is requested (that is, when the URL ends with the / character). All the other attributes are same as those which are described in previous section.

Save and quit the file.

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Step 5: Open firefox.

Figure.3.14 Opening firefox

Now, we open firefox to test our webpage that we have created.

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Step 6: Type the address of song directory in url bar.

Figure.3.15 Download Page

To check whether download page is successfully created or not we type the address of “song” folder in url bar. If the above page is displayed, it means that we have successfully created the download page.

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1.7. Adding Authentication to a webpage

Step 1: Create a directory in /var/www/html/

Figure.3.16Creating song directory

This directory is created to save the files that we are going to host on download page.

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Step 2: Create some files in song directory.

Figure.3.17 Creating files in song

We are using mp3 files as downloading files. Here we are creating some mp3 files that will be used as downloading files.

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Step 3: Open httpd configuration file.

Figure.3.18Editing http configuration

httpd.conf file contains the configuration settings for the Apache server.

Edit the httpd.conf file using your vi editor using the vi command. Once loaded, there are a number of settings that need to be changed to match our environment.

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Step 4: Add the directory information and path as shown below.

Figure.3.19Adding server data

The Directory Index directive allows you to specify a document to be served to a client when a directory is requested (that is, when the URL ends with the / character). All the other attributes are same as those which are described in previous section.

Save and quit the file.

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Step 5: Now, create a hidden file in song directory.

Figure.3.20 Create Hidden File

Now we create hidden file which contains information about which users will be able to access the download page.

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Step 6: Type the following in that file.

Figure.3.21 Editing Hidden File

Here we are specifying the information about the site or page that we have created and its location.

Save and quit the file.

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Step 7: Restart service httpd

Figure.3.22Restarting httpd Service

httpd.conf file contains the configuration settings for the Apache server.

Edit the httpd.conf file using your vi editor using the vi command. Once loaded, there are a number of settings that need to be changed to match our environment.

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Step 8: Add password to existing user for visiting the web page as follows.

Figure.3.23 Adding Password

In this step, we are allocating username and password to the download page.

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Step 9: Open firefox and type the address of song directory in url bar.

Figure.3.24 Webpage Asking Authentication

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Step 10: Type user name and password to access the page

Figure.3.25 Information Being Entered

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Step 11: If user name and password is correct you will be redirected to download page.

Figure.3.26 Download Page Reached

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1.8.Hosting two websites on single IP address

Step 1: Open httpd configuration file.

Figure.3.27 Opening Httpd Configuration file

httpd.conf file contains the configuration settings for the Apache server.

Edit the httpd.conf file using your vi editor using the vi command. Once loaded, there are a number of settings that need to be changed to match our environment.

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Step 2: Enter the alias server information as follows.

Figure.3.28 Adding Server Information

The ServerAdmin directive defines an administrative email address for people wishing to contact the root for your site,

Next the ServerName and ServerAlias directives need to be defined so that the web server knows which virtual host this configuration file refers to.

we need to define where the web site files are going to be located using the Document Root directive. The tradition is to use /var/www/html

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Step 3: Create html file in/var/www/html/file.htm

Figure.3.29Creating html file

Now, create the /var/www/html/ directory and place an malala1.html file in it.

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Step 4: Enter the message in that file.

Figure.3.30 Inserting Data in File

In this file, we are supposed to write html coding or just a simple message to be displayed.

Save and exit.

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Step 5: Now, edit the host file using command “vi /etc/hosts” and enter the IP address of server, host name and server name.

Figure.3.31 Adding Host

It is beneficial to trick your workstation into believing that a certain hostname points to a test or development server instance of that hostname instead of the production (current live) instance.

In Linux, this is done by modifying the /etc/hosts file on your workstation. Simply open the file with vi editor and add a line to the file with the IP address of the test server and the name of the production server.

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Step 6: Open firefox and type the alias server name in urlbar to reach the designed page.

Figure.3.32 Site created

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Conclusion

Linux is basically used as a free operating system. The development of Linux is

one of the most prominent examples of free and open source collaboration. Red

Hat Linux, assembled by the company Red Hat is a popular Linux based

operating system.theHypertext Transfer Protocol (HTTP) is an application

protocol for distributed, collaborative, hypermedia information system which is

developed under the LINUX operating system.A web Browser is a very common

example of http server. The given project shows the steps of how to create an

http server using the Linux operating system.

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Future Work

The interoperability framework provides a high level context and structure within

which interoperability discussion can occur. It identifies key categories and issues

that need to be addressed. It will not provide reference architecture and a high

level model that identifies the primary systems involved in the future “smart grid”

along with key boundaries information change and interactions. Such architecture

ad model is needed in the future.

The architecture would be based on foundation that distributed generations,

demand response and transmission\distributed technology will become automated

through the use of model large scale, distributed computing technology.

In order to fully evaluate the expected benefits of the proposed architecture here is

a need to implement this architecture in a real grid environment, which then can

be tested for evaluation of scalability and reliability .the architecture provides a

basis for the implementation of the experimental prototype for future research, and

it could be implemented on a grid implementation in the real environment to

develop a grid enabled application, demonstrate the feasibility of semantic

heterogeneity, and evaluate the implementation of the proposed architecture.

There are many avenues that can be explored on the basis of this study. The

architecture proposed as the potential to widely applicable, but has yet to be

proven for its functional feasibility when implemented in a real environment.

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Bibliography

http://www.basicconfig.com/linux/http

http://computernetworkingnotes.com/network-administration/how-to-configure-yum-server-in-rhel6.html

http://rbsrhel.blogspot.in/2013/03/rhel-6-yum-server-and-client.html

http://en.wikipedia.org/wiki/Red_Hat_Linux

http://yourlinuxzone.blogspot.in/2011/12/configure-http-server-on-red-hat.html

http://www.ehowstuff.com/how-to-install-http-server-on-rhel-6/

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