Input Output Management

Input Output Management

·        Managing input & output in Windows XP involves many operating system components.

·        User-mode processes interact with an environment subsystem and not directly with kernel-mode components.

·        The environment subsystem pass input & output request to the input & output manager, which interacts with devices drivers to handle such request.

·         Several device drivers, organized into a driver stack, cooperate to fulfill an input & output request.

·        The plug and play manager dynamically recognizes when new devices are added to the system and allocates and deallocates  resources, such as input & output ports or DMA channels, to them.

·        The power manger administers the operating system’s power management policy.

BUFFERING

·        Buffer overflow weakness is one of the many disadvantages of this type of security computer.

·        Buffer overflow attacks occur when the excessive Attacker provide input on the plan on the run.

·        Buffer overflow results from the weakness of the programming language c, c + +, fortran, and assembly, which does not automatically check the limit input when the program is executed.

·        The program is so complex, until programmers themselves do not know the weaknesses of the program.

·        Relies on external data to control the program.

·        Buffer is provided at the memory allocation, such as arrays or pointers in C. in the language C and C + +, there is no automatic restrictions on buffer, where users can write through the input buffer. For example:

int main () {

int buffer [10];

buffer [20] = 10;

}

·        Program in C above is a valid program, and each compiler to compile without error.

·        A process is a program in execution.

Spoiling Techniques

·        In computer science, spooling refers to a process of transferring data by placing it in a temporary working area where another program may access it for processing at a later point in time.

·        The normal English verb "spool" can refer to the action of a storage device that incorporates a physical spool or reel, such as a tape drive.

·        Spooling refers to copying files in parallel with other work.

·     The most common use is in reading files used by a job into or writing them from a   buffer on a magnetic tape or a disk.

·      Spooling is useful because devices access data at different rates. The buffer provides a waiting station where data can rest while the slower device catches up.

 FILE SYSTEM MANAGEMENT

Also referred to as simply a file system or file system.
  -The system that an operating system or program uses to organize and keep track of files.
-For example, a hierarchical file system is one that uses directories to organize files into a tree structure.
-Although the operating system provides its own file management system, you can buy separate file management systems.

 -These systems interact smoothly with the operating system but provide more features, such as improved backup procedures and stricter file protection.

File Sharing

  -Sharing of files on multi-user systems is desirable
  -Sharing may be done through a protection scheme
  -On distributed systems, files may be shared across a network
  -Network File System (NFS) is a common distributed file-sharing method

Directory Structure

- A collection of nodes containing information about all files.

-Both the directory structure and the files reside on disk.
 -Backups of these two structures are kept on tapes

File Mapping
- File mapping is the association of a file's contents with a portion of the virtual address space of a process.
- The system creates a file mapping object (also known as a section object) to maintain this association.
- A file view is the portion of virtual address space that a process uses to access the file's contents.
- File mapping allows the process to use both random input and output (I/O) and sequential I/O.
- It also allows the process to work efficiently with a large data file, such as a database, without having to map the whole file into memory.
- Multiple processes can also use memory-mapped files to share data.
- Processes read from and write to the file view using pointers, just as they would with dynamically allocated memory.
- The use of file mapping improves efficiency because the file resides on disk, but the file view resides in memory.
- Processes can also manipulate the file view with the Virtual Protect function.

protection and security consept

I.            protection and security concept.
security

Security software is available in many forms. For users who intend to surf the Internet, antivirus software is the basic software should be owned. This antivirus software will scan every file sent and received from the internet to check the probability of a virus. Two major antivirus software suppliers are Norton and McAfee. both the supplier has a good reputation in the international market. To remain effective, antivirus software should be updated often because many viruses are created every day. The virus enters the operating system when it successfully invades undetected.

protection

Addition of firewall system is a personal choice. This system will provide another layer of added protection when users on the Internet. Each program must obtain permission from the firewall to the computer to send and receive any information that comes from the Internet. Computer firewall can be modified, allowing users to allow any program that they can trust. For programs that do not know the origin, Firewall will block any action by any of these programs to seek permission from the user.

protection and security concept.

Protection concepts
The aim of the concept of computer virus protection is to create suitable safeguards with which the occurrence of computer viruses in the IT systems of an organisation can be prevented or detected as early as possible. In this way, countermeasures can be taken and possible damage can be minimised. In the protection against computer viruses it is essential that the safeguards are consistently adhered to and that technical countermeasures are constantly updated. This requirement is due to the continual occurrence of new computer viruses or variants of viruses. The development of operating systems, programming languages and application software may also provide opportunities for computer viruses to attack. This should therefore be taken into account and suitable countermeasures should be taken.



Security concepts
Certain concepts recur throughout different fields of security:
Assurance - assurance is the level of guarantee that a security system will behave as expected
Countermeasure - a countermeasure is a way to stop a threat from triggering a risk event
Defense in depth - never rely on one single security measure alone
Exploit - a vulnerability that has been triggered by a threat - a risk of 1.0 (100%)
Risk - a risk is a possible event which could cause a loss
Threat - a threat is a method of triggering a risk event that is dangerous
Vulnerability - a weakness in a target that can potentially be exploited by a threat security


Recognize security policy and mechanism.
Protection mechanisms

In computer science, protection mechanisms are built into a computer architecture to support the enforcement of security policies. A simple definition of a security policy is "to set who may use what information in a computer system.

- a mechannism for controlling the access of programs, processes, or users the resources defined by the computer system.

- the protention mechanism ensures the enforcement of a certain policy.

- policy is established in several ways:

i. system design.

ii. system management.

 iii user defined.



Security in computer system

- security is an enternal operating systems problem-providing controlled access to programs and data stored in the computer
- security is mainly focused on malicious behavior of entities external to the system,affecting computer assets:

i. software

      ii. data
      iii.Hardware

Memory management

Memory management

Memory management is the act of managing computer memory. In its simpler forms, this involves providing ways to allocate portions of memory to programs at their request, and freeing it for reuse when no longer needed. The management of main memory is critical to the computer system.

Virtual memory systems separate the memory addresses used by a process from actual physical addresses, allowing separation of processes and increasing the effectively available amount of RAM using disk swapping. The quality of the virtual memory manager can have a big impact on overall system performance.


Memory management systems on multi-tasking operating systems usually deal with the following issues.

ProtectionMain article: Memory protection
Processes should not be able to reference the memory for another process without permission. This is called memory protection, and prevents malicious or malfunctioning code in one program from interfering with the operation of other running programs.

SharingMain article: Shared memory
Even though the memory for different processes is normally protected from each other, different processes sometimes need to be able to share information and therefore access the same part of memory. Shared memory is one of the fastest techniques for Inter-process communication.

Logical organizationPrograms
are often organized in modules. Some of these modules could be shared between different programs, some are read only and some contain data that can be modified. The memory management is responsible for handling this logical organization that is different from the physical linear address space. One way to arrange this organization is segmentation.

Physical OrganizationMemory
is usually divided into fast primary storage and slow secondary storage. Memory management in the operating system handles moving information between these two levels of memory.

7.1 Explain protection and security concept.

Sharing of program and data among us a computer system necssitataes strong emphis on protection ang security measures in an os.Both protection and security imply guarding again intrusion in an os.

However,in keeping with the convention followed in os literature,a distinction is made between two types of intrusion

7.1 Security policy and mechanism

The term security and protection are often used interchangeable.

Nevertheless, it is frequently useful to make a distinction between the general

problems involved in making sure that files are not read or modified by

unauthorized persons, which include technical, managerial, legal and political

issues on the one hand, and the specific operating system mechanism used to

provide security on the other to avoid confusion, we will use the term security to

refer to the overall problem, and the term protection mechanisms to refer to the

specific operating system mechanisms used to safeguard information in the

computer. The boundary between them is not well defined, however.

A more interesting problem is what to do about intruders. These come in

two varieties. Passive intruders just want to read files they are not authorized o

read. Active intruders are more malicious; they want to make unauthorized

changes to data.

7.2 Elobrate authentic basic.

7.21 Password

Passwords are often used to protect object in the computer system,

in the absence of more complete protection scheme. They can be considered a

special case of either keys or capabilities. For instance, a password could be

associate with each resource such as file. Whenever a request is made to use the

resource, the password must be given. If the password is correct, access isgranted. Different passwords may be associated with different access rights. For

example, different password may be used for reading, appending and updating a

file.

7.22 Artifact

A completely different approach to authorization is to check to see

if the user has some item, normally a plastic card with a magnetic stripe on it.

The card is inserted into the terminal, which then checks to see whose card it is.

This method can be combined with a password, so a user can only log in if he

1. has the card

2. knows the password

Automated cash dispensing machine usually work this way.

Another technique is signature analysis. The user sign his name with a special

pen connected to the terminal and the computer compares it to a known

specimen stored online. Even better is not to compare the signature, but compare

the pen motion made while writing it. A good forger may be able to copy the

signature, but will not have a clue as to the exact order in which the stroke were

made.

7.23 BIOMETRIC

Yet another approach is to measure physical characteristic that are

hard to forge. For example a finger print or a voiceprint reader in the

terminal could verify the users identity (it make the search go faster if the

user tells the computer who he is, rather then making the computer

compare the given fingerprint to the entire database)

Finger length analysis is surprisingly practical. When this is used

each terminal has a device. The user inserts his hand into it and the length

of all his finger is measured and check against the database

7.3 Elaborate protection concept an access control

•  Protection is concerned with keeping data safe from improper or unauthorized access and physical damage .  When faulty memory resulted in the disk data being corrupted, technicians replacing disk, after disk and the problem not going away we need decided to swap the memory as part of an error exploration.
• We can control access to files, specifying who and how can read, write, execute, delete and list files.
• Access control has a number of strategies:
• Access control list (ACL) specifies user names or groups, and types of access.
• Associate passwords and access control (read only, modify with tracked changes) per file.

System DOS

·         MS-DOS is a single-tasking operating system, which means that it can run only one program at a time. The MS-DOS user interface is a command-line interface, which means that users must type text-based commands and responses when interacting with the operating system.

·         MS-DOS treats each separate program and piece of data as an individual file. Each file has a name, which is broken down into two parts: a file name and an extension.

·         The input/output system consists of two files and a ROM (Read Only Memory) chip. While the two files are on your disks and are loaded into memory when the computer starts, they are normally hidden from your view and not available to you for changing.

·          Disk Operating System  is responsible for creating and/or deleting files in the file system and managing the input and output of data in the file system.

                                                                                                                        

WINDOWS 2000

^·          Windows 2000 unites defined roughly the user-friendliness, pug & play and USB device support of Windows 98 and the safety and stability of the Windows NT family

^·           It is a multitasking, multiprocessing operating system and supports up to 2 processors of the x86 32- bit and 64 The field of application of this operating system is suitable as a single user computer or as a client in company networks. bit architecture with SMP.

^·           Networks are supported with the protocols TCP/IP, NWLink and AppleTalk. Windows 2000 supports the data interchange in decentralised working groups and central domains. 

^·           The SFC (System File Protection) offers protection from overwrite of Windows system files. It is possible to create hardware profiles for different hardware configurations with the settings of all devices and services. 

^{WINDOWS NT}

^·          Windows NT is a Microsoft Windows personal computer operating system designed for users and businesses needing advanced capability.

^·          A new file directory approach called Active Directory that lets the administrator and other users view every file and application in the network from a single point-of-view.

^·          Dynamic Domain Name Server (DNS), which replicates changes in the network using the Active Directory Services, the Dynamic Host Configuration Protocol (DHCP), and the Windows Internet Naming Service (WINS) whenever a client is reconfigured.

^·          The ability to create, extend, or mirror a disk volume without having to shut down the system and to back up data to a variety of magnetic and optical storage media.

^·          A Distributed File System (DFS) that lets users see a distributed set of files in a single file structure across departments, divisions, or an entire enterprise.