A, B, C, D are the four security classifications of the computer system. These are as per the guidelines the evaluation criteria of the U.S. Department of Defense Trusted Computer System. The primary purpose of the classifications of the security of the computer system is the determination and the modelling of the protection of the system and the solutions. Let us discuss the types of the security in brief. After this, you would get to read about Linux, another operating system.
1. Type A-
When a system has to type A security, then this implies that it has the highest level categorization of the security. This section of the computer system security makes the use of formal design and the specifications of the technique to verify the process. The best thing about the type A security is that the user gets a high degree guarantee of the security of the process.
2. Type B-
In this categorization of the security classification of the computer system, the user gets the required and mandatory protection to its system. It contains all the properties of the C2 class system. The type B system of securing the computer system attaches a sensitive label to every object which is under it. There are three types of this security classification type. These are the B1, B2, and B3.
• B1- It does the work of maintenance of the security label of every object which is there in the system. The security label is used to make ease of the control of the access, and it is due to the fact that it makes all the decisions of controlling the system.
• B2- The principal activity which the B2 type has to do is the extension of the sensitive labels and provide it to every computer system resource. The storage objects are the examples of the activities done by the type of the security classification. The system supports the conversion of the channel and the audition of the events.
• B3- Creation of the user groups and the lists for granting the access and revoking it from the given named object.
3. Type C-
The third type of the security classification use the audit capabilities to provide protection and the accountability of the user. Like the second type, it has two types-
• C1- It helps in the security of the private information and keeping the other users to stay away from the deletion and the reading of the data by incorporating the controls. Most of the versions of the system are C1 class.
• C2- The C2 type of the classification of the security adds capabilities of the C1 level system with the help of individual-level access.
4. Type D-
It is termed as the lowest level of the security classifications. In simple words, it gives the minimum protection from the malicious users. For example, MS-DOS and Window 3.1 etc.
It was about the security classifications. Now, read on and comprehend yourself and attain the knowledge about Linux.
Operating System, UNIX has various popular versions, and one of them is the Linux.
Linux is an operating system in which the source codes are available to the reader openly. Moreover, the usage is free for all the readers. You can reach the source code of the content anytime and read. The primary purpose of designing the Linux was considered for the compatibility of Unix. Both the operating systems have a similar set of functions and operations. Let us see the components of Linux System.
Components of the Linux System
There are three modules of this operating system. These are as follows-
1. System Library- The special programs and the functions which help the system and the application program to access the features of the kernel. Most of the functionalities of the operating system are implemented by the system libraries. In addition to this, they don’t require any module of the kernel and the codes of the accessing rights.
2. Kernel- The core part of the Linux is the kernel. This part has to hold all the responsibilities of the management of the operating system. Various modules compose the maximum part of the kernel. Also, the work of the direct interaction with the underlying hardware has to be accomplished by the kernel. Hiding the low-level details of the hardware from the system and the programs of the application is possible with the abstraction provided by the kernel.
3. System Utility-The responsibility of doing the specialized and the individual level tasks is with the system utility.
The difference between the user and the kernel mode
The system library contains the codes which are not required to run in kernel mode. Other system programs and user programs in User Mode. Both these programs do not access the kernel code and the system hardware. The access of the kernel functions to get the low-level tasks of the system is with user programs and utilities. They use it the system libraries to reach the accessing level.
There are special privileged modes which the kernel component code executes and those modes are called kernel mode. Moreover, they have the full access to all the computer resources. The kernel mode has various functions to perform. The first and the foremost is the representation of the single process and the execution of the single address space. The kernel mode is the fastest and the most efficient manner. For this, it does not need any context. Running and providing the system services to processes as well as the protection of the hardware access is the other function of the kernel.
Essential Features of the Linux Operating System
The list of the characteristics of the operating system is extensive. Have a look at the elements of the list and comprehend yourself. It is explained in easy language.
1. Open Source- As mentioned above as well, the source code of Linux is available to all freely. In addition to this, they are based on the community and development project. Enhancing the capability of the operating system needs teamwork. The manufacturers of the operating system are making efforts to work in collaboration to reach the high level of the abilities hold by the operating system. The best thing is that it has been evolving and the efforts are not beating the air.
2. Portable- The operating system can work on the different hardware platform and work on various application programs. It works in the same way in all the diverse range of the platforms in which it is deployed. It is the general and common definition of portability in layman language.
3. Multi-User- More than one user can operate the system at the same time. Multiple users can access the system, its resources and the application program, the memory, RAM at the same time.
4. Shell- For the execution of the command in the operating system, the operating system provides an interpreter program. The shell considers the operations to be done and call the application of the programs.
5. Hierarchical File System- There should be the management of the user files and the system files in the computer system. The operating system then provides a standard structure of the data to achieve it.
6. Security- As we have discussed the protection of the computer system, all these features like the same. The operating system provides security of the files by giving the controlled access to the encrypted files and marking it with id and password.
The architecture of the Linux System
There are several layers in which the operating system works. These are as follows-
1. Hardware Layer- This is the layer which has the composition of the hardware devices. The devices can be anything from RAM, HDD, CPU and many more.
2. Kernel- The core component of Linux operating system is the kernel. Here in this, there is a direct interaction of the hardware with the different peripheral devices. In addition to this, the operating system provides it low-level services to the upper components of the layer.
3. Shell- It hides the functions of the kernel and their complexity from the users. The interface of the kernel which is the shell takes the commands from the user, and after this, it begins the execution of the functions of the kernel.
4. Utilities- The utility programs provide most of the functionalities of the operating system.