Introduction

Active Info Gathering

Networking Primer

Networking Fundamentals

• In computer networks, hosts communicate with each other through the use of a network protocol
• Network protocols ensure that different computer systems, using different hardware and software, can communicate with each other.
• There are a large number of network protocols used by different services for different objectives/functionality Communication between different hosts via protocols is transferred/facilitated through the use of packets.

Packets: are nothing but streams of bits running as electric signals on physical media (Ethernet, Wifi) used for data transmission These electrical signals are then interpreted as bits (zeros and ones) that make up the info

Header : contains important info about the packet: where it comes from / where it has to be sent to

• has a protocol-specific structure Payload: actual content you want to send

The network layer is responsible for logical addressing, routing, and forwarding data packets between devices across different networks. primary goal: determine the optimal path for data to travel from the source to the destination, even if the devices are on separate networks.

• Internet Protocol(IP) : IPv4(32bits addresses), IPv6 (128bits addresses)
• Internet Control Message Protocol(ICMP): used for error reporting and diagnostics include ping, traceroute, and various error messages

IP Functionality

• logical Addressing
  • IP addresses serve as logical addresses assigned to network interfaces
  • IP addresses are hierarchical and structured based on network classes, subnets, and CIDR(Classless Inter-Domain Routing) notation
• Packet Structure
  • IP organizes data into packets for transmission across networks. Each packet consists of a header and a payload
  • The header contains essential information, including the source and destination IP addresses, version number, time to live(TTL), and protocol type