What's the Difference Between GPT and MBR When Partitioning

Master Boot Record Vs. GUID Partition table

Introduction:

We make several partitions of our hard disk to keep various types of data or to make an isolation between system data and user data. The question is, how does the OS know the partition structure of the hard disk? That information has to come from somewhere. This is where MBR (Master Boot Record) and GPT (GUID Partition Table) come into play. While both are architecturally different, both play the same role in governing and provide information for the partitions in the hard disk.

Master Boot Record (MBR)

MBR is the old standard for managing the partition in the hard disk, and it is still being used extensively. The MBR resides at the very beginning of the hard disk and it holds the information on how the logical partitions are organized in the storage device. In addition, the MBR also contains executable code that can scan the partitions for the active OS and load up the boot-up code/procedure for the OS.

A master boot record (MBR) is a special type of boot sector at the beginning of partitioned computer mass storage devices like fixed disks or removable drives. The concept of MBRs was publicly introduced in 1983 with PC DOS 2.0.

The MBR holds the information on how the logical partitions, containing file systems, are organized on that medium. Besides that, the MBR also contains executable code to function as a loader for the installed operating system—usually by passing control over to the loader's second stage, or in conjunction with each partition's volume boot record (VBR). This MBR code is usually referred to as a boot loader.

The organization of the partition table in the MBR limits the maximum addressable storage space of a disk to 2 TB per partition with a total no of four partitions.

This is how a typical MBR disk layout looks like:

There are several pitfalls with MBR. First of all, you can only have 4 partitions in the hard disk and each partition is limited to the only 2TB in size. This is not going to work well with the hard disk of big storage space, say 100TB. Secondly, the MBR is the only place that holds the partition information. If it ever gets corrupted (and yes, it can get corrupted very easily), the entire hard disk is unreadable.

GUID Partition Table (GPT)

GPT is a standard for the layout of the partition table on a physical hard disk, using globally unique identifiers (GUID). Although it forms a part of the Unified Extensible Firmware Interface (UEFI) standard (Unified EFI Forum proposed replacement for the PC BIOS), it is also used on some BIOS systems because of the limitations of master boot record (MBR) partition tables, which use 32 bits for storing logical block addresses (LBA) and size information.

With GPT, you can create theoretically unlimited partitions on the hard disk, even though it is generally restricted to 128 partitions. Unlike MBR that limits each partition to only 2TB in size, each partition in GPT can hold up to 9.44ZB for a 512-byte block (1 ZB is 1 billion terabytes). In Microsoft Windows, that size is limited to 256 TB.

This is how a GPT disk layout looks like:

From the GPT Table Scheme diagram above, you can see that there is a primary GPT at the beginning of the hard disk and a secondary GPT at the end. This is what makes GPT more useful than MBR. GPT stores a backup header and partition table at the end of the disk so it can be recovered if the primary tables are corrupted. It also carries out CRC32 checksums to detect errors and corruption of the header and partition table.

You can also see that there is a protective MBR in the first sector of the hard disk. Such a hybrid setup is to allow a BIOS-based system to boot from a GPT disk using a boot loader stored in the protective MBR’s code area. In addition, it protects the GPT disk from damage by GPT-unaware disk utilities.

Conclusion

In most cases, you will be fine with either MBR or GPT. It is only in a situation where you need four primary partitions or when you need to have a partition bigger than 2TB, that you need to use GPT, or convert MBR to GPT. Also, for the newer model of computer that uses UEFI, it will only support GPT.



(References: Wikipedia)

Remedy for error message: "The file 'Asms' on Windows XP Professional CD-ROM is needed" while loading Winows XP

"The file 'Asms' on Windows XP Professional CD-ROM is needed" error message when you install Windows XP
1. When you receive the error message, press SHIFT+F10 to start a command session.
2. Type regedit.exe, and then press ENTER.
3. Click HKEY_LOCAL_MACHINE.
4. On the File menu, click Load Hive, and then load %Windir%\System32
\Config\System.sav.
5. When you are prompted to specify a name, type Test.
6. Locate and then click the following key: HKEY_LOCAL_MACHINE\Test\ControlSet1\Control\Class\{4D36E965-E325-11CE-BFC1-08002BE10318}
7. Delete the UPPERFILTERS and LOWER FILTERS registry keys.
8. Repeat steps 6 and 7 for the other ControlSet# keys under the Test hive.
9. Click File, and then click Exit to quit Registry Editor.
10. If the path in the error message is the correct drive letter for the CD-ROM drive, click OK to continue the Setup program.
11. If you receive the error message again, the Setup program cannot correctly read from the CD-ROM drive, or the path information is incorrect. In this case, restart your computer and let the Setup program resume.

NOTE: If this does not solve then please change your CD-ROM and continue set up.

How To Disable User Access Control (UAC) Popups in Windows

"Windows needs your permissions to continue."

User Account Control can be annoying, but you should think twice before disabling it. UAC's pop-ups make it simpler to use a standard Vista account since you can temporarily elevate to an administrator account by typing a password. Using a standard user account helps to protect your computer from attack since malware's impact can be limited when not running with administrator rights.
If you still want to disable UAC popups, follow these instructions to disable User Account Control.

(a) Type "user account" into the Windows Vista Start menu and click on User Account when it appears in the Programs list.

(b) Click on the Turn User Account Control on or off-link.

(c) If UAC is currently turned on, you will be prompted for approval. Provide the administrator's password or click Continue if you are sure you want to turn UAC off.

(d) This isn't a time when you should just blindly dismiss the UAC prompt. It's best to use a standard account for your general computing and provide an administrator's password when UAC prompts. It helps protect your computer from attack. If you do turn off UAC, seriously consider the implications and think about turning it back on as soon as possible.

 (e) Uncheck the box next to Use User Account Control (UAC) to help protect your computer to disable UAC. Click OK to save your changes.

Windows 7/8 Secuity Settings

Introduction

1. The flexibility and convenience of Windows-based Operating System (OS) has resulted in being a widely used desktop environment. It is essential to use these desktop environments in a secure manner to avoid exploitation of the possible vulnerability of the OS. This article explains how to configure the security settings in Windows Operating System.

Windows Security Center

2. The Windows Security Center in Windows 8 /Windows 7 lets you view and change important security settings. It monitors your settings and notifies you if there is a problem. It is intended to serve as a hub to your computer's security settings, making it easier to understand what you need to do to keep your computer secure. Although you can choose settings other than those recommended, the Center helps you know when your settings are different from those suggested by Microsoft.

3. The control panel for the Windows Security Center organizes security settings into four categories for easy viewing. A green background indicates the category's settings are optimal, yellow indicates the settings may need attention, and red indicates a problem likely exists.

4. The easiest way to open the Windows Security Center is to type "security center" into the search box integrated into the Vista Start menu. The list of programs will be filtered down to only the Security Center, and you can start it by clicking the link or pressing Enter. You can also access the Security Center through the Windows Vista Control Panel. 5. Click on one of the links below to learn about the security settings Windows Security Center monitors.

Firewall
 
6. The firewall category in the Windows Security Center lets you see if Windows Firewall is on. Windows Firewall is a free firewall included in Windows Vista that can prevent unwanted access to your computer.

7. If you turn it off, Windows Security Center will draw your attention to the problem by changing the background of the category heading to red. A button makes it easy to turn Windows firewall on, or you can click on the Windows Firewall link in the left panel to change the Windows firewall settings
 
Automatic Updating
 
8. The automatic updating category of the Windows Security Center lets you easily see if your computer is configured to automatically download and install security and other updates from Microsoft. If your computer isn't configured for automatic updates, a button to change the settings is provided. You can also click the Windows Update link in the left panel to change your settings.
 
Malware Protection
 
9. The malware protection category in the Windows Security Center monitors your use of antivirus and other anti-malware software. Windows Vista includes Windows Defender, a program that protects against spyware and other malware. Vista does not, however, include an antivirus program. The Windows Security Center makes it easy to see if you have the malware protection you need, and it provides links to help you purchase antivirus software and control Windows Defender.
 
Other Security Settings
 
10. Windows Security Center also monitors your Internet Explorer options and makes sure you have User Account Control turned on. The Internet Explorer options help to secure your computer and data from malicious Web sites while User Account Control prevents unwanted changes to your system.

Speed-up your Internet connection

The Truth

The system reserves 20% of your band-width. Means you are paying your ISP for 100% , where as you are using only 80% of it. Cheated no....

How to free your Band-width

(1) Run -> gpedit.msc

(2) Local Computer Policy -> Computer Configuration -> Network ->QoS Packet Scheduler -> Limit reservable bandwidth

(3) Double click Limit reservable bandwidth

(4) Click Enable and set Bandwidth limit to 0 %

Now you will be able to use 100% of your Internet band width.

Make a Hidden Folder (Folder Without Name)

(1) Right Click on desktop ->new -> Folder
(2) Rename folder ATL + 255 ( Press ALT Key and type 255 with numpad).
(3) Right Click the Folder -> Properties ->Customize -> change icon.
(4) Select the blank icon.



You are done.........
Where is your folder ???

Disable or Hide Administrative Shares

Hidden Shares:

A hidden share is identified by a dollar sign ($) at the end of the share name. Hidden shares are not listed when you look through the shares on a computer or use the net view command. Windows create hidden administrative shares that administrators, programs, and services can use to manage the computer environment on the network. By default, Windows can enable the following hidden administrative shares:

(1) C$ D$ E$ - Root of each partition. For a Windows workstation computer only members of the Administrators or Backup Operators group can connect to these shared folders. For a Windows NT Server/W2K Server computer, members of the Server Operators group can also connect to these shared folders.

(2) ADMIN$ - %SYSTEMROOT% This share is used by the system during any remote administration of a computer. The path of this resource is always the path to the system root (C:\Windows).

(3) FAX$ - On W2K Server, this used by fax clients in the process of sending a fax. The shared folder temporarily caches files and accesses cover pages stored on the server.

(4) IPC$ - Temporary connections between servers using named pipes essential for communication between programs. It is used during remote administration of a computer and when viewing a computer's shared resources. This share can be very dangerous and can be used to extract large amounts of information about your network, even by an anonymous account.

(5) NetLogon - This share is used by the Net Logon service of a computer while processing domain logon requests, and by Pre-W2K computers when running logon scripts.

(6) PRINT$ - %SYSTEMROOT%\SYSTEM32\SPOOL\DRIVERS Used during remote administration of printers. This shares may not be used , if you are not connect to any LAN /WAN. These shares are hidden, but available with full control to domain administrators. The drive letter, followed by the $ sign is the name, and it is shared from the root. When trying to attain a highly secure network, you may wish to address this potential security issue by disabling these shares, or at least restricting their permissions to specific users or services. Better practice to disable these hidden shares.

How to disable:

There are two ways to disable it.

(1) Right Click My Computer -> Manage ->Shared Folders ->Shares -> Right Click on the Share and Disable.

(NOTE: If you disable an administrative share , it will not be automatically enabled after you restart your computer. )




(2) Permanently disable by using folowing regedit:

Hive:HKEY_LOCAL_MACHINE
Key:SYSTEM\CurrentControlSet\Services\LanManServer\Parameters
Name:AutoShareServer (for Windows 2000/2003/2008)
Name: AutoShareWks (for Win XP/Vista)
Type: REG_DWORD
Value: 0 



Security Risk:

Unfortunately this registry hack does NOT stop the IPC$ share and this is a share that is often used by hackers to enumerate systems before attack since it can yield a wealth of information about your system names, your user names, and more. If your ACL permissions are not correct or you haven't disabled anonymous user access or you haven't disabled the guest account then this port can lead to total system compromise !

Hide Your Computer Name And Disable File Shares

NetBIOS Vs DNS:

Earlier Netbios was used instead of DNS for name resolution. But after 2000, Windows started using DNS (Domain Name System) and SMB (Server Messsage Block) Direct Hosting at TCP/IP port 445 for requests instead of port 139
.
The Risk:

This is basically used for name resolution and File sharing. NetBIOS on the WAN or over the Internet, however, is an enormous security risk. All sorts of information, such as your domain, workgroup and system names, as well as account information is obtainable via NetBIOS.

The SMB (Server Message Block) protocol is used among other things for file sharing in Windows OS. In Windows Servers it ran on top of NetBT (NetBIOS over TCP/IP), which used the famous ports 137, 138 (UDP) and 139 (TCP). In Windows, Microsoft added the possibility to run SMB directly over TCP/IP, without the extra layer of NetBT. For this they use TCP port 445. By standard both port 139 and 445 is open to get the highest degree of compatibility. A client will try to request on both ports and continue the communication on the port which responds first.

How to Disable?

Disable SMB use of Netbios port 139 (Forces use of port 445):

1. On the Start menu, point to Settings, and then click Network and Dial-up Connections
2. Right-click Internet facing connection, and then click Properties.
3. Select Internet Protocol TCP/IP and select Properties
4. Click Advanced and select the WINS tab
5. Tick Disable NetBIOS over TCP/IP and click Ok

To disable SMB use of port 445 with this DWORD (Forces use of port 139):

[HKEY_LOCAL_MACHINE \SYSTEM \CurrentControlSet \Services \NetBT \Parameters]
SMBDeviceEnabled = 0

Disable SMB use of port 139 and 445 (Disables nbt.sys driver):

1. Right-click My Computer on the desktop, and then click Manage.
2. Expand System Tools, and then select Device Manager.
3. Right-click Device Manager, point to View, and then click Show hidden devices.
4. Expand Non-Plug and Play Drivers.
5. Right-click NetBios over Tcpip, and then click Disable.

Disable SMB completely:

1. On the Start menu, point to Settings, and then click Network and Dial-up Connections
2. Right-click Internet facing connection, and then click Properties.
3. Select Client for Microsoft Networks, and then click Uninstall.
4. Follow the uninstall steps.
5. Select File and Printer Sharing for Microsoft Networks, and then click Uninstall.
6. Follow the uninstall steps.

If you are using a router as your Internet gateway then you will want to ensure that it does not allow inbound or outbound traffic via TCP ports 135-139.

If you’re using a Firewall then you should also block the same ports - TCP ports 135-139.

Clipboard Hack:

Shocking News about CTRL + C :

Ctrl + C may be the most important and frequent work we do everyday. But it’s not very safe thing to do. Read on to know why? What happens when you press Ctrl + C while you are online?

We do copy various data by Ctrl + C for pasting elsewhere. This data is stored in clipboard and accessible from the net by anyone by using JavaScript and ASP. This is called clipboard Hack.

Just Try this:

1. Copy any text by Ctrl + C
2. Click on the link : http://www.sourcecodesworld.com/special/clipboard.asp
3. You will see the text you copied will be accessed by this web site.

Surprise!

Don’t you? It is extremely easy to extract the data stored in your clipboard to steal your sensitive information. So do not keep sensitive data (like Password, Credit card No, Pin No etc.) in the clipboard while you are connecting to net.

It’s true that the data last copied for paste operation can be stolen when you visit such web site which uses these scripting languages and your sensitive data will be saved on the database of others server.

How it works :

It can be done by using this simple JavaScript:
/*
var content = clipboardData.Getdata(“Text”);
alert (content) ;

*/
How to Overcome this hack :

To avoid this hack use following settings in your browser (IE):
1. Tools ->Internet options ->security ->Internet ->custom level
2. Scripting -> Allows paste operation via script ->disable.

Now the content of your clipboard is safe.

In latest versions of IE, this issue has been fixed :)