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YAML

Key Value Pairs

name: Solomon Stroup
age: 36
hobbies:
  - coding
  - simracing
manager:
  name: Colten Hilgendorf
  age: 73
  hobbies:
    - golfing
  manager:

Child representation:

child:
  child:
    child:
      child:
        child:
          child:
            child:

JSON

Also Key Value pairs

{
    "name":"Solomon Stroup",
    "age":36,
    "hobbies":[
        "coding",
        "simracing"
    ],
    "manager":{
        "name":"Colten Hilgendorf",
        "age":73,
        "hobbies":[
            "golfing"
        ],
        "manager":null
    }
}

Child Representation:

{
    "child":{
        "child":{
            "child":{
                "child":{
                    "child":{
                        "child":{
                            "child":null
                        }
                    }
                }
            }
        }
    }
}
# but...this takes up one line:
{"child":{"child":{"child":{"child":{"child":{"child":{"child":null}}}}}}}

Network Part 0 Intro

  • Local networking - Ethernet
  • Routing
  • Segmenting, ports, sessions
  • Applications

Best way to understand networking is to fully understand the OSI 7 Layer Model. Definition: https://osi-model.com/ Key Phrase: People don't need those stupid packets anyway. 1-7 ;)

Network Layer 1 Physical

Types:

  • Ethernet Cable - The actual physical cable
  • WIFI - Radio Frequencies
  • Fiber - Light

Notes:

  • Physical connections between places
  • a Hub is needed to connect more than two devices. Anything received on one port is transmitted to all the ports - this is not a router. it doesn't route from one machine to a specific machine, nor does it act as a switch.
  • No way to avoid collisions Each layer understands the layers below them, but not the ones above them. An ethernet cable doesn't understand anything because it's a Layer 1 Physical thing.

Network Layer 2 Data Link

  • Frame that contains the source and destination and payload that travels across the Layer 1 physical media
  • Identifies devices
  • Layer 2 has a way to detect and work around collisions which can do Unicast 1:1 and Broadcast communications 1:ALL
  • Switch instead of a hub which helps with collisions.

Decimal to Binary conversion (IP Addresses)

image.png

Network Layer 3 Network

  • IP - the frame is then wrapped with data that says where this packet is going.
  • Subnets and subnet masks
  • Routes - where to forward this packet
  • Route tables - multiple routes
  • Router - moves packets from source to destination while encapsulating on Layer 2
  • ARP - Address Resolution Protocol - sends to MAC addresses via the IP address
  • Device to device communications over the Internet
  • Can be delivered out of order

Network Layer 4 Transport and Layer 5 Session Layer

  • TCP and UDP
  • TCP Handshake will be used.
  • Session layer 5 lies on top of Transport Layer 4.
  • Ordering packets and lost packets are fixed here.
  • Flow control
  • Delay control
    image.png

NAT

  • IPv4 ONLY
  • Running out of IPv4 addresses.
  • This translates private IPv4 addresses into Public
  • Static NAT - 1 private to 1 fixed public address (Internet Gateway)
  • Dynamic NAT multiple private to multiple public addresses
  • PAT Port Address Translation - MANY private to 1 Public (NAT Gateway)

Subnetting

Breaks networks up into smaller pieces.

Class A Network Class B Network Class C Network

DDOS

  • designed to overload websites
  • they compete against legit connections
  • distributed - comes from multiple locations
  • usually initiated from botnets

SSL and TLS