SYS140 Class - eitan-j/tech-journal GitHub Wiki

11/9/2020

  • Wires in network cables are color coded
  • CIA
    • Confidentiality
      • Info is only accessible to authorised user
    • Integrity
      • Info can only be modified by authorised user
    • Availability
      • Info can be accessed when needed

11/5/2020

Domain Name System (DNS)

  • Resolves hostnames and IP addresses to each other
  • Uses UDP by default
  • Port 53 by default
  • cmd ipconfig /displaydns shows DNS cache
  • When you try to connect to website
    • Checks for website IP in DNS cache
    • If not in cache, asks DNS server for website IP
    • If website not in cache, asks higher DNS server, etc.

11/2/2020

Ports

  • Ports - socket
  • cmd netstat -an to see ports
  • cmd netstat -abn to see ports and processes
  • Unix lsof
  • [::1] - IPV6 loopback
  • [::] - IPV6 all ports

10/29/2020

Networking

  • Jumbo frames - bigger packets
  • Ethernet - 100m limit
  • VLAN - virtual LAN
  • Ethernet over Power
  • Power over Ethernet

10/26/2020

Networking

  • Devices can directly communicate to devices on the same Local Area Network (LAN)
  • ARP - find MAC address from IP address
  • ARP cache - temporary cache of ARP data
  • Metropolitan Area Network - multiple LANs connected in a city
  • Wide Area Network - big
  • Wireless versions of networks
  • Server - computer that shares data
  • Workgroup - group of computers in a network
  • Domain - central controller
  • Switch - communication between hosts
  • Hub - broadcasts incoming data
  • Cables use "Cat" standards
  • RJ45 ports are used
  • Cable management is important

10/19/2020

Linux

  • Differing GUIs
  • VLC is useful
  • CrossOver - use Windows programs in Linux
  • top - shows memory info

10/19/2020

Operating Systems - Windows

  • 32 bit - antiquated - limited to 4 GB ram - x86
  • 64 bit - modern - ultra high ram limit - better performance
  • WSUS - download update to locate server - pushes to computers on network
  • Updating can make stuff stop working
  • Not updating can be insecure
  • Event Viewer - shows logs
  • regedit - avoid modifying if possible

10/12/2020

Operating Systems

  • Kernel - operating system
  • Drivers - software that allow hardware access
  • Open standards - generic instructions - special drivers not needed