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Shadow Cipher

Operating system - Composition and Management

Remote Connection and SSH

  • Work desktop vs Home Computer Ex: Transfer data from home computer to remote computer

  • Remote Shell(SSH) A protocoal implemented by other programs to securely access one computer from another.

  • Shell code:

ssh cindy@104.131.122.215
  • Private
  • Public
  • Virtual Private Network(VPN) Allows you to connect to a private network, like your work network, over the internet.

Operatinfg System

Remote connections on windows

  • PuTTY A free, open source software that you can use to make remote connections through several network protocols, including SSH.
  • PuTTY configuarions
putty.exe -ssh cindy@104.141.122.215 22
  • Remote Desktop Protocol
  • Microoft Terminal Services Client
  • Remote connection using GUI

Components of an Operating System

  • Operatinfg System: The whole package that manages our computer’s resources and let us interact with it.

  • User Spaces Applications

  • Kernal Spaces:

    • Process manager
    • Memory manager
    • File manager
    • I/O manager

  • Hardware

  • System programs

  • User Interfaces

  • Windows

  • Mac

  • Linux

  • Ubuntu

  • Debian

  • Red Hat

  • Our kernel optmizes memoru usage and makes sure our applications have enough memory to run.

  • I/O Management Anything that can give us input, or that we can use for Output of data.

  • File management

  • Process management

  • Memory management

  • I/O management

Files and File systems

  • File handling

  • Data

  • Metadata

  • File System

  • NTFS

  • Encryption

  • Faster access speeds

  • Security

  • ReFs

  • HFS+

  • ext4

  • We write data to our hard drive in the form of adata blocks

  • Block storage: Imroves faster handling of adata because the data isn’t stored as one long piece and can be accessed quicker.

  • File -> Metadata

    • File Owner
    • Permissions
    • File Size
    • Date Modified
    • Date Created
    • File Type

  • File extension The appended part of a filename that tells us what type of file it is in certain operating systems.

Process management

  • process: A program that’s executing, like our internet browser or text editor.

  • Program: Am application that we can run, like Chrome.

  • User Space

  • Kernel - Processes

  • Hardware

  • Time slice A very short interval of time that gets allocated to a process for CPU execution

  • Kernel Creates processes, efficiently schedules them, and manages how processes are terminated

Memory management

  • Virtual Memory The combination of hard drive spces and RAM that acts like memory that our processes can use

  • Program -> Pages

    • Virtual Memory - RAM, Hard drive Spaces
      • Physical Memory -RAM

I/O Management

  • I/O Devices Devices that perform input and Output
  • Ehen you’re troubleshooting or solving a problem with a slow machine, it’s usually so sort of hardware resource deficiency.

Ineract with the OS: User Space

  • Shell

  • Graphical User interface

  • Shell A program that interprets text commands and sends the to the OS to execute.

  • Bourne Again Shell

  • Powershell

Logs

Files that record system events on our computer, just like a system’s diary.

The Boot Process

  • BIOS/UEFI A low-level software that initializes ourcomputer’s hardware to makesure everything is good to go.

  • Poer on Self Test

  • Poer On -> BIOS/UEFI -> Boot Device -> Boot loader -> OS -> Kernel -> system process

  • Bootloader A small program that loads the operating system.