Windows booting Procedure

What is booting?

Before checking the booting procedures we should know the meaning of booting. Booting is just the process of starting or resetting the computer. There are two types of booting: cold booting and warm booting. Cold booting is the booting process happening when we first turn on computer and warm booting is the processes happening when we reset the computer. During the booting process the computer loads the operating system to its memory and prepares it for use.

Booting procedure of Windows operating system

Functions of BIOS

The first process starting when you turn on your computer is BIOS i.e, Basic Input Output System. BIOS has two functions, to conduct POST and read MBR.



a) POST - POST stands for Power On Self Test. POST checks all the hardware devices connected to a computer like RAM, hard disk etc and make sure that the system can run smoothly with those hardware devices. If the POST is a failure the system halts with a beep sound. 

b) Now BIOS checks the boot priority. We can set the boot priority as CD drive, hard disk or floppy drive.

c) MBR - The next duty of BIOS is to read the MBR. MBR stands for Master Boot Record and its the first sector on a hard disk. MBR contains the partition table and boot loader.

Functions of Boot loader

Now BIOS has passed the control to boot loader and boot loader is a small program which loads kernel to computers memory. Actually there are two stages of boot loaders, stage 1 boot loader and stage 2 boot loader. MBR contains the stage 1 boot loader and stage 1 boot loader is a link to the stage 2 boot loader. The stage 2 boot loader resides in the boot partition and it loads the kernel to memory.

Boot files and functions

There are three boot files in a Windows operating system and they are NTLDR, NTDETECT.COM and Boot.ini. The boot files are found in the active partition of hard disk and its normally C drive in a Windows machine. 

NTLDR - NTLDR stands for NT Loader and its the second stage bootloader. The path of NTLDR is C:\Windows\i386\NTLDR.

Boot.ini - Boot.ini contains the configuration files of NTLDR. When the operating system is loaded we cannot pass any arguments to kernal, so those arguments are passed through boot.ini. You can edit boot.ini by opening through notepad. The path of Boot.ini is C:\boot.ini.



NTDETECT.COM - This file detect hardware's and passes information to NTLDR. Using the collected information the NTLDR creates a hardware key and this key is used to detect hardware's. A new hardware key is generated after each reboot of the operating system and that's why system asks to reboot after installation of a new hardware. The hardware keys created by NTLDR can be found in Windows registry at HKEY_LOCAL_MACHINE -> HARDWARES.

Kernel and its functions

After executing the functions of boot files the control is passed to Kernel. ntoskrnal.exe is the kernel file in a Windows machine and its path is C:\Windows\system 32\ntoskrnal.exe. Kernel acts as a layer between software and hardware. The library file hal.dll (C;\Windows\system32\hal.dll) helps Kernel to interact with hardware's. HAL stands for Hardware Abstraction Layer and this hal.dll file is machine specific. Now the drivers for hardware's are loaded from the file C:\Windows\system32\config\system and the Kernel is loaded to primary memory.

Services and log in procedure

When kernel is loaded in the primary memory services for each process is started and the registry entry for those services can be found at HKEY_LOCAL_MACHINE - System - Current control set - Services. Winlogon.exe (C:\Windows\system32\winlogon.exe) is the last service started during this process. Winlogon.exe starts the log in procedures of windows machine. It first calls the library file msgina.dll (C:\Windows\system32\msgina.dll). MSGINA stands for Microsoft Graphics Identification and Authentication and it provides the log in window. Now msginal.dll passes the control to LSA (Local Security Authority), it verifies the username and password from the SAM file. SAM (Security Accounts Manager) contains the information about all users created in a Windows operating system.

Now the booting procedure is over and we have reached the desktop of Windows operating system.

Read more »

How to Break Into a Windows PC (and Prevent It from Happening to You)

If you're trying to break into a Windows computer—whether you've forgotten your password or are hatching a more sinster plan—you have quite a few options. Here's how to do it, and how to keep your own computer protected.

There are a few methods to breaking into a computer, each with their own strengths and weaknesses. Here, we'll go through three of the best and most common methods, and nail down their shortcomings so you know which one to use—and how to exploit their weaknesses to keep your own computer secure.

The Lazy Method: Use a Linux Live CD to Get at the Files

If you don't need access to the OS itself, just a few files, you don't need to go through much trouble at all. You can grab any Linux live CD and just drag-and drop files onto a USB hard drive, as you would in any other OS.

Full size

How It Works: Just download the live .iso file for any Linux distribution (like the ever-popular Ubuntu) and burn it to CD. Stick it in the computer you want to access and boot up from that CD. Pick "Try Ubuntu" when it comes up with the first menu, and it should take you right into a desktop environment. From here, you can access most of the hard drive just by going to the Places menu in the menu bar and choosing the Windows drive. It should see any NTFS drives just fine.

Note that depending on the permissions of some files, you might need root access. If you're having trouble viewing or copying some files, open up a terminal window (by going to Applications > Accessories > Terminal) and type in gksudo nautilus, leaving the password blank when prompted. You should now have access to everything.

How to Beat It: This method can give you access to the file system, but its main weakness is that the malicious user still can't access any encrypted files, even when using gksudo. So, if the owner of the computer (or you) has encrypted their files (or encrypted the entire OS), you won't get very far.

Sneaky Command-Line Fu: Reset the Password with the System Rescue CD

If you need access to the operating system itself, the Linux-based System Rescue CD is a good option for breaking in. You'll need to do a bit of command line work, but as long as you follow the instructions closely you should be fine. Hat tip to our friends at the How-To Geek.

How It Works: Just download the .iso filefor the System Rescue Live CD and burn it to disc. Boot from the disc and hit the default option when the blue screen comes up. After everything loads and you're presented with a command-line interface, type fdisk -l to see the drives and partitions on your computer. Pick the Windows partition (usually the largest NTFS partition) and note the name, e.g. /dev/sda3.

Then, run the following command:

ntfs-3g /dev/sda3 /mnt/windows –o force

Make sure to replace /dev/sda3 with the partition you noted earlier. Next, cd to your Windows/System32/config directory with this command:

cd /mnt/windows/Windows/System32/config

We want to edit the SAM file in this folder, so type the following command to get a list of users:

chntpw –l SAM

Note the username you want to access, and then type the following command, replacingWhitson Gordon with the username in question.

chntpw –u "Whitson Gordon" SAM

At the next screen, choose the first option by typing the number 1 and hitting Enter. This will clear the user password, making it blank. When it asks you to write hive files, hit y and press Enter. It should say OK, and then you can type reboot to reboot the computer. When you boot into Windows, you'll be able to log in to that user's account without a password.

How to Beat It: Once again, the weakness of this method is that it still can't beat encryption. Changing the password will disallow you access to those encrypted files, which, if the user has encrypted their entire OS, makes this method pretty useless. If they've only encrypted a few files, though, you'll still be able to access all the unencrypted stuff without a problem.

Brute Force: Crack the Password with Ophcrack

Where the other two methods are vulnerable to encryption, this method will give you full access to everything the user can access, including encrypted files, since this method relies on finding out the user's password instead of bypassing it.

How It Works: We've actually gone through this method before, but it doesn't hurt to have a refresher. All you need to do is download and burn the Ophcrack Live CD(use the Vista version if you're cracking a Windows 7 PC) and boot from it on your computer. It'll take a little bit of time to boot, but eventually it will bring you to a desktop environment and start attempting to crack passwords. This may take a while. You'll see the passwords pop up in the top pane of the window, though, when it finds them (or, if it doesn't find them, it'll notify you). You can then reboot and log in to Windows using those passwords.

How to Beat It: While this method works on encrypted OSes, it can't crack every password out there. To increase your chance of having an uncrackable password, use something complicatedand greater than 14 characters. The stronger your password, the less likely Ophcrack will be able to figure it out.

---

There are a lot of methods to break into a Windows computer (in fact, we've featured some of them before), but these are a few of the best and most widely useful. Try it for yourself on your own machine—you'll be shocked at how easy it is for someone to get into your machine. The takeaway? Encrypt your data and use a long, strong password if you want to keep yourself protected, or you could be vulnerable to the above tricks.

Read more »

NETWORK CONNECTIONS

Read more »

NETWORKS FULL FORMS

TCP/IP – Transmission Control Protocol /

                 Internet Protocol

LAN –      Local Area Network

MAN –     Metropolitan Area Network

WAN –     Wide Area Network

Modem – Modulation(tor)/Demodulation(tor)

URL –       Uniform Resource Location

FTP –       File Transfer Protocol

HTTP –    Hyper Text Transfer Protocol

PPP –       Point to Point Protocol

GSM –     Global System for Mobile

CDMA –  Code Division Multiple Access

WLL(WiLL)–Wireless in Local Loop

SMS –      Short Message Service

WWW –   World Wide Web

HTML –   Hyper Text Markup Language

XML –      eXtensible Markup Language

NFS –       Network File System

ARPANET – Advanced Research

                       Projects Agency

NSFnet – National Science Foundation

NIU –       Network Interface Unit

NIC -        Network Interface Card

TAP –      Terminal Access Point

        (NIU = NIC = TAP)

VGM –     Voice Grade Medium

DGM –      Data Grade Medium

STP –        Shielded Twisted Pair

UTP –       Unshielded Twisted Pair

LED –       Light Emitting Diode

LD –         Laser Diode

Kbps –      Kilo bits Per Second

KBps –      Kilo Bytes Per Second

Mbps  -     Mega Bits  Per Second

MBps –     Mega Bytes Per Second

Gbps  -      Giga Bits Per Second

GBps –      Giga Bytes Per Second

OFC –       Optic Fiber Cable

                  Fiber Optic Cable

KHz –        Kilo Hertz

MHz –       Mega Hertz

GHz –        Giga Hertz

THz –        Tera Hertz

Bps –         Bytes Per Second

bps   -         Bits Per Second

PDA –        Personal Digital Assistants

P-P   -         Point to Point

AM –         Amplitude Modulation

FM -           Frequency Modulation

PM –          Phase Modulation

A/F –         Audio Frequency

(Txd – Transmit       Rxd – Receive

RTS – Request to Send

CD – Carrier Detect

DSR – Data Set Ready

CTS – Clear to Send

DTR – Data Terminal Ready)

RJ45 –        Registered Jack – 45

BNC –        Bayone – Neill – Concelman

AUI –         Attachment Unit Interface

SNA –        Systems Network Architecture

VFIR –      Very Fast Infrared

URI –        Uniform Resource Identifier

URN –       Uniform Resource Name

MIME –     Mail and Multipurpose Internet

                   Mail Extensions

POP –        Post Office Protocol

SMTP –     Simple Mail Transfer Protocol

NNTP –     Network News Transfer Protocol

HTTP –      Hyper Text Transfer Protocol

NTP –         Network Time Protocol

IMAP –       Internet Mail Transfer Protocol

SLIP –        Serial Line Internet Protocol

IPCP –        IP Control Protocol

NCP –        Network Control Protocol

LCP –        Link Control Protocol

PC –          Personal Computer

ISP –         Internet Service Provider

SIM –       Subscriber Identity Module

TDMA –  Time Division Multiple Access

TDM –      Time Division Multiplexing

IDEN –      Integrated Digital Enhanced

                  Network

WCDMA –Wideband CDMA

PSTN –      Public Switched Telephone

                    Network

3G –            Third Generation

UMTS –      Universal Mobile

                    Telecommunications System /

                    Universal Mobile Telephone

                     System

EDGE –      Enhanced Data rates for Global

                   Evolution

SMSC –      Short Message Service Center

HLR –        Home Location Register

Email –      Electronic Mail

Fax –          Fascimile

VSNL –     Videsh Sanchar Nigam Limited

DNS –        Domain Name Server

DHTML–   Dynamic Hyper Text Markup   

                   Language

DECnet–    Digital’s family of

                   communication protocols

IE –             Internet Explorer

Boolean Algebra Laws

(1)Properties of 0 and 1:

     0 + X = X, 1 + X = 1, 0.X = 0, 1.X = X

(2) Idempotence Law:(a)X +X = X(b)X.X = X

(3) Involution Law:          (A')' = A

(4)ComplementaryLaw:(a)X +X'=1(b)X.X'=0

(5)Commutative Law: (a) X+Y =Y+X  

                                     (b)X.Y=Y.X

(6) Associative Law:  (a)X + (Y+Z)=(X+Y)+Z

                                   (b)X.(Y.Z)=(X.Y).Z

(7)Distributive Law:  (a) X(Y+Z)=XY+XZ

                                   (b) X+YZ=(X+Y)(X+Z)

(8) Absorption Law:   (a) X+XY=X 

                                    (b)X(X+Y)+X

(9) Third distributive Law:  X+X'Y=X+Y

(10)Demorgan’s Theorems (1) (X + Y)'=X'Y'

                                             (2) (XY)'=X' + Y'

All the best for ur comp board exams....

Read more »