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Top 10 List of Week 03
- Disk Fragmentation
Disk Defragmentation itu terdengar seperti mengembalikan pecahan-pecahan yang berceceran menjadi satu. Dalam kasus komputer, hal ini berhubungan dengan membuat data-data yang berceceran dan terpisah tempat dalam hard disk dikumpulkan dalam tempat yang sama/dekat. Kebanyakan hard disk komputer memiliki pola berputar sehingga hard disk menempatkan data dalam tempat yang berbeda ketika menulis data baru, blok-blok data diciptakan sesuai dengan urutan perintah yang diberikan. Ketika Disk De-fragmentation berlangsung blok-blok data yang sudah terbuat tersebut dikumpulkan berurutan kembali sehingga kedepannya pekerjaan membaca data lebih mudah, dengan demikin hal ini menghapus jarak antar file data yang berada dalam hard disk sehingga mempercepat kerja komputer.
- Consistency Semantics
Consistency Semantics is concept which is used by users to check file systems which are supporting file sharing in their systems. Basically, it is specification to check that how in a single system multiple users are getting access to same file and at same time. They are used to check various things in files, like when will modification by some user in some file is noticeable to others.
- File Locking in Linux
File locking is a mutual-exclusion mechanism to ensure a file can be read/written by multiple processes in a safe way. File locking is a mechanism to restrict access to a file among multiple processes. It allows only one process to access the file in a specific time, thus avoiding the interceding update problem. We all know that rm -rf / is a very dangerous command in Linux. If we execute the command as the root user, all files in the running system will be deleted. This is because Linux usually doesn’t automatically lock open files. However, Linux supports two kinds of file locks: advisory locks and mandatory locks.
- Network File System
NFS adalah singkatan dari Network File System, yang pertama kali dikembangkan oleh Sun Microsystems pada tahun 80-an, sebagai sarana untuk berbagi file pada lingkungan kerja diskless. NFS menyediakan sarana untuk berbagi file antar jaringan, sehingga suatu mesin dapat mengakses file-file di mesin lain seolah-olah mengakses file sistem lokal.
- Cryptography
Cryptography provides for secure communication in the presence of malicious third-parties—known as adversaries. Encryption uses an algorithm and a key to transform an input (i.e., plaintext) into an encrypted output (i.e., ciphertext). A given algorithm will always transform the same plaintext into the same ciphertext if the same key is used.
Algorithms are considered secure if an attacker cannot determine any properties of the plaintext or key, given the ciphertext. An attacker should not be able to determine anything about a key given a large number of plaintext/ciphertext combinations which used the key.
- Binary Exploitatiom
Binary exploitation is the process of subverting a compiled application such that it violates some trust boundary in a way that is advantageous to you, the attacker. In this module we are going to focus on memory corruption. By abusing vulnerabilities that corrupt memory in software we can often rewrite critical application state information in a way that allows us to elevate privileges inside the context of a particular application (like a remote desktop server) or perform arbitrary computation by hijacking control flow and running code of our choosing.
- What is Computer Virus?
A computer virus, much like a flu virus, is designed to spread from host to host and has the ability to replicate itself. Similarly, in the same way that flu viruses cannot reproduce without a host cell, computer viruses cannot reproduce and spread without programming such as a file or document.
In more technical terms, a computer virus is a type of malicious code or program written to alter the way a computer operates and is designed to spread from one computer to another. A virus operates by inserting or attaching itself to a legitimate program or document that supports macros in order to execute its code. In the process, a virus has the potential to cause unexpected or damaging effects, such as harming the system software by corrupting or destroying data.
- What are Browser Hijackers?
A browser hijacker is defined as a “form of unwanted software that modifies a web browser’s settings without the user’s permission.” The result is the placement of unwanted advertising into the browser, and possibly the replacement of an existing home page or search page with the hijacker page. The idea is to make users visit certain websites whether they want to or not so the hijacker enjoys higher advertising revenue. Browser hijackers may also contain spyware to obtain banking information and other sensitive data.
- Protect Your Computer from Viruses
Using an antivirus is essential when trying to keep your computer healthy and free from viruses.
Computers are an incredible technology that many of us use every day of our lives. However, they’re prone to viruses and malware that could harm our files and steal our personal data, such as banking details and social security information.
- FUSE (FileSystem in Userspace)
File systems are notoriously difficult to implement: of all the pieces that appear in an operating system, they have the highest quality bar and are often called upon more than almost any other part of the operating system; virtual memory management may be called upon more.
Of course, the fact that modern operating systems tend to make the boundaries of file systems and virtual memory a bit fuzzy doesn’t really diminish their difficulty.