Aditya Abeysinghe OS

What is the Windows NT logon process? Windows NT process is the process by which the operating systems belonging to the Windows NT family start up. The logon process for operating systems introduced by Microsoft since Windows Vista uses a slightly different architecture (methodical steps), but many steps in the windows NT process have been repeated There are many steps involved with the Windows NT logon process but this blog post summarizes the most important steps and definitions. The basic architecture of this process can be summarized as follows: A simplified Windows NT logon process Now let us understand what each section of the above flow diagram does in the Windows NT logon process. Main sections of the logon process- Security reference monitor- The security reference monitor is used to ensure which subjects have authorization to which objects. Thus, it uses the access control policy used in the operating system for its basic functioning. A security refere

What are they? First-fit and Best-fit are memory allocation schemes that were typically used in dynamic and fixed partition memory allocation schemes to allocate memory. To simplify what they are, consider the following list of jobs and the available resources. The above figure shows a list of jobs and the resources to which these jobs could be allocated.  Here to allocate the jobs, we use either the first-fit memory allocation scheme or the best-fit memory allocation scheme. The first-fit memory allocation scheme allocates on the basis of the first partition fitting the requirements.  The best-fit memory allocation scheme allocates on the basis of the best partition (one with the least memory wastage) fitting the requirements. Let us allocate the jobs first on the basis of first-fit memory allocation and then on the basis of best-fit memory allocation to understand how jobs are allocated and the pros and cons of the two schemes. Allocating using First-fit memor

About encryption- Encryption is used to ensure the confidentiality of data. For example, if you are sending an email (typically using an insecure medium), the email is prone to hacking/interception. The solution is to use encryption. The basic encryption process is as follows: The methods- Based on the purpose and complexity/simplicity two main types of encryption methods are used: 1. Symmetric encryption 2. Asymmetric encryption Pros and Cons of Symmetric encryption- In symmetric encryption, a public key is used for both encryption and decryption. Since the public key can be shared publicly, there is a high probability that if the key is hacked during transmission, it can be shared publicly. Therefore, key distribution problems arise when the key is shared over insecure mediums, such as the internet. Moreover, when more and more people join the conversation (the message/email transmission), the key management problems arise. Therefore, key management and key

What are the goals of computer security? The number of goals concerning computer security is highly debatable. However, every thoery that is been presented to date ensures three main types of goals: confidentiality, integrity and availability. In this blog post I have mentioned five types of security goals: confidentiality, integrity, availability, authenticity and non-repudiation / accountability. The following figure summarizes what each of these goals mean and who are involved with these goals and what needs to be done to ensure the goals' performance. Click on image to zoom Confidentiality- Confidentiality means that information or services should only be accessed by authorized personnel.  Click on image to zoom   Integrity-   Integrity means that information or services should only be modified by authorized personnel. Click on image to zoom Availability- Information or services should be available to authorized personnel when

What is a honeypot? Honeypots are systems used to gather information about the activity of attackers or intruders to a system. It acts like a trap to detect how a user approaches/intercepts a system, how they behave once intercepted and stores these data into its database (here the database means a storage area, not a collection of data records). A honeypot placed within the DMZ What makes a honeypot? Building a honeypot requires a PC with more preferably a UNIX based operating system and a sniffer tool. (A sniffer tool provides the capability of seeing the traffic going between the firewall and the honeypot)  Where can honeypots be placed? Honeypots can be placed anywhere in the system. They may be placed outside the DMZ, inside the DMZ or even on the internal network.  Honeypots are additional security system. Honeypots differ from firewalls in that honeypots do not filter the traffic passing them and honeypots differ from intrusion detection systems