Notes, summaries, assignments, exams, and problems for Computers

Logic Bombs and Resource Exhaustion Attacks

Logic Bombs

A logic bomb is a program that performs an action violating the site security policy when a specific external event occurs. These are typically associated with insider threats.

Example: A program that deletes a company’s payroll records when one particular record is deleted.

• The "particular record" is usually that of the person who created the logic bomb.
• The idea is that if (or when) the creator is fired and their payroll record is deleted, the company loses all those records.

Rabbits and Bacteria (Resource Exhaustion)

Rabbits or Bacteria refer to programs designed to absorb all of a specific class of system resources, leading to denial of service or system instability.

Example: For a UNIX... Continue reading "Malicious Software: Types, Threats, and Advanced Viruses" »

Pseudo Classes

Pseudo classes are selectors that can be used to style elements based on their state or position in the document. For example, the :hover pseudo class can be used to style an element when the user hovers over it with the mouse.

:nth-of-type(an+b || even || a || an)

The :nth-of-type pseudo class is used to select elements based on their position in a group of siblings. It takes an argument that specifies which elements to select. The argument can be one of the following:

• an+b: Selects every nth element, starting with the bth element. For example, 2n would select every other element, and 2n+1 would select every odd element.
• even: Selects every even-numbered element.
• odd: Selects every odd-numbered element.
• a: Selects every element.

For... Continue reading "Web Development Fundamentals" »

1. What is a Public Blockchain?

Public blockchains are open networks that allow anyone to participate. This permissionless nature means anyone can join the network and read, write, or participate in the blockchain.

Public blockchains are decentralized, meaning no single entity controls the network. Data on a public blockchain is secure because it is virtually impossible to modify or alter data once validated on the blockchain.

Features of Public Blockchains:

• High Security: Secured by mining and the 51% rule.
• Open Environment: Open for anyone to join.
• Anonymous Nature: Participants can remain anonymous, enhancing privacy.
• No Regulations: No strict regulations on platform usage.
• Full Transparency: The ledger is publicly viewable, ensuring transparency.

Benefits of Mobile Technology in Education

Statistics concluded that 20% of laptops will be mobile in the next 10 years. 40% of children aged 6-8 years old have used a smart device. Smart devices allow access to large amounts of information and feature quick boot times, wireless capabilities, portability, and long battery life.

Desktop vs Mobile Devices: A Comparison

Although mobile is continuously increasing its capabilities, it still has limits when using intense resource applications (e.g., AutoCAD).

Mobile Devices

• Instant on
• Portable
• Longer battery life
• Built-in cameras, video cameras, and microphones
• Touch-enabled, engaging content
• Wireless capabilities

Desktop and Laptop Computers

• More storage and more processing power
• Larger screen and full keyboard
• Easier

PL/SQL

PL/SQL is a procedural language designed specifically to embrace SQL statements within its syntax. PL/SQL program units are compiled by the Oracle Database server and stored inside the database. And at run-time, both PL/SQL and SQL run within the same server process, bringing optimal efficiency. PL/SQL includes procedural language elements like conditions and loops. It allows declaration of constants and variables, procedures and functions, types and variable of those types and triggers. It can support Array and handle exceptions (runtime errors).

Differences between SQL and PL/SQL

• SQL is a single query that is used to perform DML and DDL operations.
• PL/SQL is a block of codes that used to write the entire program blocks/ procedure/ function,

Fresh leaks from the Chinese forum Saraba1st point to the imminent release of refreshed Clevo gaming laptops powered by the new Comet Lake-S desktop-grade CPUs, expected to launch this spring. User Liaojings1 obtained internal slides detailing the upcoming X170 laptops, which replace the aging P7xx-series, finally bringing Clevo's designs in line with competitors like Dell/Alienware and MSI.

Chassis and Design Improvements

To accommodate desktop-grade CPUs, the X170 features a redesigned chassis with larger rear exhaust grills. Additional upgrades include:

• Enhanced Audio: More powerful stereo speakers and a dedicated woofer.
• RGB Lighting: Integrated lighting on the rear and underneath the chassis.

Display and Visuals

Clevo is adopting slim-bezel... Continue reading "Clevo X170 Gaming Laptops: Comet Lake-S Power and Upgrades" »

Key Concepts in Microsoft Word and Computer Applications

1. Microsoft Word Application Type

Which type of computer application is Microsoft Word an example of?

Word processing

2. Touchscreen Right-Click

Which action enables you to right-click on a touchscreen?

Press and hold for a few seconds

3. Word 2016 Document Starting Point

A preformatted document used as a starting point in Word 2016 is known as what?

A template

4. Wordwrap Functionality

Word uses wordwrap. If a word does not fit at the end of a line, what happens to that word?

It is automatically moved to the next line.

5. Understanding Inline Objects

What does inline object refer to?

A picture or object positioned directly in the text at the insertion point, just like a character in a sentence.

6.

Data Storage Conversion:

• 1 gigabyte (GB) equals 1,024 megabytes (MB).
• 1 megabyte (MB) equals 1,024 kilobytes (KB).
• To convert gigabytes to kilobytes, multiply by 1,024 twice. For example: 1 GB = 1,024 MB * 1,024 KB = 1,048,576 KB.
• To convert gigabytes to megabytes, multiply by 1,024. For example: 1 GB = 1,024 MB
• To convert 20 megabytes to bytes: 20 MB = 20 * 1,024 KB * 1,024 bytes = 20,971,520 bytes
• To convert 2 gigabytes to kilobytes: 2 GB = 2 * 1,024 MB * 1,024 KB = 2,097,152 KB

Example: SHKRONJA A has a value of 1010, B - 1011, C - 1100, D - 1101, E - 1110, F - 1111.

Binary Number Representations

There are three main ways to represent signed numbers in binary:

1. Signed Magnitude

• Positive Numbers: Standard binary representation.
• Negative Numbers: The

Implementing a New System Call in the Kernel

Required Files to Add

• /usr/src/test_kernel/SystemCalls/test_call.c:
  • Creates system call pointer.
  • Exports the pointer so that the system call module can access it.
  • Defines the system call wrapper.
• /usr/src/test_kernel/SystemCalls/Makefile: obj-y := test_call.o (Compiles files directly into the kernel).

System Module Implementation

• /usr/src/test_kernel/SystemModule/syscallModule.c:
  • Holds module code.
  • Implements system call behavior.
  • Registers system call pointer to the proper system call handler.
• /usr/src/test_kernel/SystemModule/Makefile: obj-m := syscallmodule.o (Compiles file as a module).

Required Files to Modify

• /usr/src/test_kernel/arch/x86/entry/syscalls/syscall_64.tbl: Add the system call to the table.
• /usr/