red hat linux installation and root password cracking

7/27/2019 Red Hat Linux Installation and Root Password Cracking.

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Created by :-

Himani Mittal (B.tech-CSE) NIEC,delhi

Preeti Raheja(B.tech-CSE) NIEC,delhi

Harshal Gambhir(B.tech-CSE)NIEC,delhi

A RHEL Presentation

1. Unix

2. Linux

3. Computer Startup

4. Linux Kernel5. Top Level Directories

6. CLI Installation

7. GUI Installation

8. Boot Startup Commands

9. Vi Editor

10. Commands Used

11. Root Password Cracking

First version created in Bell Labs – 1969 AT&T licenses source code for low cost

Trademarks UNIX name, ―UNIX‖ name closely held

Licensees must create new name for their operating systems

Many UNIX ―Flavors‖ emerge

PRINCIPLES

Everything is a file. Including hardware

Configuration data stored in text

Small, single-purpose programs Avoid Captive User Interfaces

Ability to chain programs together to perform complex tasks.

Fresh Implementation of UNIX APIs.

Open Source Development model.

Supports wide variety of hardware.

Supports many networking protocols and configurations.

Fully supported.

Linux is a UNIX-like OS.

Multi-user and Multi-tasking.

Wide hardware support. Checklist.

Fully Supported.

COMPUTER STARTUP

Booting is a bootstrapping process that starts operating systems when

the user turns on a computer system

A boot sequence is the set of operations the computer performs when

it is switched on that load an operating system

SEQUENCE OF BOOTING

1. Turn on

2. CPU jump to address of BIOS (0xFFFF0)

3. BIOS runs POST (Power-On Self Test)

4. Find bootable devices

5. Loads and execute boot sector form MBR

6. Load OS Boot loader could be more aptly called the kernel loader. The task at

this stage is to load the Linux kernel

Optional, initial RAM disk

GRUB and LILO are the most popular Linux boot loader.

KERNEL The kernel is the central part in most computer operating systems because of its

task, which is the management of the system's resources and the

communication between hardware and software components

Kernel is always store on memory until computer is turn off

Kernel image is not an executable kernel, but a compress kernel image

zImage size less than 512 KB

bzImage size greater than 512 KB

TASK OF KERNEL • Process management

• Memory management

• Device management

• System call

INIT PROCESS

• The first thing the kernel does is to execute init program

• Init is the root/parent of all processes executing on Linux

• The first processes that init starts is a script /etc/rc.d/rc.sysinit • Based on the appropriate run-level, scripts are executed to start various

processes to run the system and make it functional

CLI LINUX INSTALLATION

Pentium Pro or better with 256 MB RAM

64-bit Intel/AMD with 512 MB RAM

2-6 GB Disk Space

Bootable CD

Other processor architectures supportedItanium 2, IBM Power, IBM Mainframe.

System Requirements

Download LINUX

To install Red Hat, you will need to download the ISO

images (CD Images) of the installation CD-ROMs

from http://fedora.redhat.com

Download the i386 images for 32 Intel Processors,PPC images for Apple Macintosh and x86_64 for

for 64 bit AMD Processors

Burn the iso CD images on CDs and use these CDs

as Installation CDs (typically 4)

1. place the DVD or CD #1 in your DVD/CD-ROM drive

and boot your system from the DVD/CD-ROM.2. The installation program then probes your system

and attempts to identify your CD-ROM drive.

Points To Consider :-

a) To abort the installation process at this time, reboot your machine and

then eject the boot media.

b) Run mediacheck if you encounter a problem during installation.

c)For IDE (ATAPI) DVD/CD-ROM if the installation program fails to find it and

asks you what type of DVD/CD-ROM drive you have then try this bootcommand. Restart the installation, and at the boot: prompt enter linux

hd X =cdrom . X values depends upon master and slave:-

•a — first IDE controller, master

•b — first IDE controller, slave

•c — second IDE controller, master •d — second IDE controller, slave

Choosing mode to create partition .

Selecting custom layout i.e. user will select partition ,their mount point

and space required.

Similarly for other partitions follow the same procedure

Swap is a file system as well as partition so ,select its file

system as swap and provide space twice as that of RAM

and select OK.

NOTE:-

It is necessary to create atleast three partitions namely ,

ROOT(/),/boot and swap.

One can select to add grub password or leave it blank.

Selecting area for installation of boot loader ,from where linux will boot .

Here either name of host can be set or it shall be automatically assigned

as ‗localhost‘.

In linux software packages can be installed at time of linux installation

,which is solely user choice , if they want to choose packages at same

It would take some time for installation and after installation

restart your system .

Graphical Mode Installation

Press for starting installation in GUI mode

Linux Installation

What is a Partition?

Partitioning is a means to divide a single hard drive into many logical

drives.

A partition is a contiguous set of blocks on a drive that are treated

as an independent disk. A partition table is an index that relates sections of the hard drive to

partitions.

Linux Installation

Why have multiple partitions?

Reduce the risk of system failure in case a partition becomes full.

Runaway processes or maniacal users can consume so much diskspace that the operating system no longer has room on the harddrive for its bookkeeping operations. This will lead to disaster. Bysegregating space, you ensure that things other than the operatingsystem die when allocated disk space is exhausted.

Encapsulate your data. Since file system corruption is local to apartition, you stand to lose only some of your data if an accidentoccurs.

Linux Installation

Partition Fields

Device: This field displays the partition's device name.

Start: This field shows the sector on your hard drive where thepartition begins.

End: This field shows the sector on your hard drive where the partitionends.

Size: This field shows the partition's size (in MB).

Type: This field shows the partition's type (for example, ext2, ext3, or vfat).

Mount Point: A mount point is the location within the directoryhierarchy at which a volume exists; the volume is "mounted" at thislocation. This field indicates where the partition will be mounted.

Linux Installation

Filesystem Types

ext2—

An ext2 file system supports standard Unix file types (regular files, directories, symbolic links, etc). It provides the ability to assignlong file names, up to 255 characters. Versions prior to Red HatLinux 7.2 used ext2 file systems by default.

ext3— The ext3 file system is based on the ext2 filesystem and has

one main advantage — journaling. Using a journaling filesystemreduces time spent recovering a file system after a crash as there isno need to fsck the file system.

swap— Swap partitions are used to support virtual memory. In other words, data is written to a swap partition when there is not enough

RAM to store the data your system is processing.vfat — The VFAT file system is a Linux filesystem that is compatible with

Windows 95/NT long filenames on the FAT filesystem.

Linux Installation

Recommended Partitioning Scheme

Unless you have a reason for doing otherwise, it is recommendedthat you create the following partitions:

/boot partition – contains kernel images and grub configuration andcommands

/ partition/var partition

/home partition

Any other partition based on application (eg /usr/local for squid)

Swap partition — swap partitions are used to support virtual memory.In other words, data is written to a swap partition when there is notenough RAM to store the data your system is processing. The size of your swap partition should be equal to twice your computer's RAM.

Linux Installation

Disk Partition

IDE Disk Partitions/dev/hda (Primary Master Disk)/dev/hda1 (First Primary Partition)/dev/hda2 (Second Primary Partition)

/dev/hdb (Primary Slave Partition)/dev/hdb1/dev/hdc (Secondary Master/Slave Partition)/dev/hdc1

SCSI Disk Partitions/dev/sda1, /dev/sda2/dev/sdb1, /dev/sdb2/dev/sdc1, /dev/sdc2

Linux Installation

Software RAID and LVM

Software raid (redundant array of inexpensive disk)

raid 0 (striping)

raid 1 (mirroring)

raid 5 (striping with parity)

lvm (logical volume manager)

Linux Installation

Boot Loader

In order for the BIOS to load an OS it looks for instructions on thefirst sector of a hard drive.

On the first sector of the hard drive resides the master boot record

(MBR), and is where a boot loader is initialized.

Depending on the boot loader, additional files may be stored andread from a partition on the hard drive.

After this step the boot loader begins to start the operating system,

and is not used again until the next boot.

7 basic internal commands, shown in next slides.

Linux noprobe

Common Problem:

- Red Hat installer does not detect the SCSI controller or network card

Execution:

- boot : linux noprobe.

Linux mediacheckCommon problem:- to inspect disks.

Execution:- boot: linux mediacheck

- Options: 1.Cd found : click ok to test cd before installation else press

2.Test to test current cd or eject to eject current disc

and insert another disc.

Linux askmethod

Use: remote installation through -

1. NFS

2. FTP

3. HTTP

4. VNC

5. PXE

6. Kickstart

Linux ddUse:

This argument causes the installation program to promptyou to use a driver diskette.

Linux updateUse:

to apply updates for the anaconda installationprogram from a USB storage device .

Memtest86Use :perform memory testing before you install Red Hat

Enterprise Linux by entering memtest86 at the boot:

1. Boot the system

2. Press ‗e‘.

3. On 2nd

line again press ‗e‘

• Press space and write ‗1‘ or ‗single‘

•Press ‗b‘. •Linux will boot in terminal 1.

•Write command :-passwd root

•New password can now be set and restart the system.

Commands of Vi Editor ESC for command mode

Change Delete Yank(Copy)

Line cc dd yy

Letter cl dl yl

Word cw dw yw

Sentence ahead c) d) y)Sentence behind c( d( y(

Paragraph ahead c{ d{ y{

Paragraph behind c} d} y}

save changes Abandon changesExit :wq! :q or :q!

Do not exit :w! :e!

Forcing Changes:

Save changes

Common commands

Add a directory

#mkdir –p /a/b/c

Nested directorycreated.

Common commandsDelete a file :

#rm filename

Example- #rm /doc

do you want to delete /doc file?[y/n]:y

/doc deleted.

Delete a directory :#rm –r directory name

Example- #rm –r /a

delete /a/b? y

delete /a/b/c? y

delete /a/b/c/d? y(directory deleted.)

Obtaining the Red Hat Enterprise Linux Installation Media

Although RHEL is an open source operating system, and as such, the sourcecode is freely downloadable, the binary installation images are only available as

part of a paid Red Hat Enterprise Linux subscription. In addition to access to the

installation images for RHEL, this subscription also provides technical support for

the operating system. If you already have a paid subscription, log into

your Red Hat account to download the operating system. If you would like to try

out RHEL before purchasing, Red Hat provides a 30-day trial. To register for a

trial, visit the Red Hat website at http://www.redhat.com/rhel/details/eval/ and

complete the registration process.

The installation distribution can be downloaded as either six individual CDROM

images or a single DVD image. Unless you specifically need to use CD images

the DVD installation image is strongly recommended. The DVD image is namedusing the following convention:

Having downloaded either DVD or CDROM images, either burn them to disk,

configure your virtualization environment to treat them as DVD or CDROM drives

red hat linux installation and root password cracking

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