Network and Network Security

###Networking Basics

Data Packet

A basic unit of information traveling across a network. It has three parts:

1. >Header - Includes sender IP, destination MAC address, and protocol.
2. >Body - Contains the data/content.
3. >Footer - Includes receiving device information.

Bandwidth

The volume of data a device receives per second.

TCP (Transmission Control Protocol)

An internet communication protocol that forms connections between devices to stream data.

IP (Internet Protocol)

A set of standards for routing and addressing packets during data transfer between devices.

Port

Software-based locations for sending and receiving data across a network.

• >Port 25 - Email
• >Port 443 - HTTPS
• >Port 20 - Large file transfers

###TCP/IP Model

A framework for organizing and transmitting data across networks.

Layers:

1. >Network Access - Handles packet creation and transmission.
2. >Internet - Assigns IP addresses and connects networks.
3. >Transport - Manages traffic flow and error control.
4. >Application - Defines how data packets interact with devices (e.g., file transfers, emails).

Comparison with OSI Model

###IP Addressing

Types:

1. >IPv4 - Uses decimal-separated numbers (e.g.,

   192.168.1.1

   ).

1. >IPv6 - 32-character hexadecimal addresses for expanded device support.

Categories:

• >Public IP - Assigned by ISPs, visible to the internet.
• >Private IP - Used within local networks, invisible to the internet.

###MAC Address

Unique alphanumeric identifiers assigned to network devices.

• >Switches use MAC addresses to route packets efficiently.

###Network Protocols

Common Protocols:

• >ARP - Resolves MAC addresses.
• >HTTPS - Secure website communication.
• >DNS - Converts domain names to IP addresses.
• >ICMP - Reports transmission errors.
• >UDP - Fast but unreliable data delivery.

###Wireless Protocols

• >IEEE 802.11 (WiFi) - Wireless LAN standards.
• >WPA/WEP - Wireless security protocols for secure connections.

###Firewall and VPN

Firewall:

• >Types: Hardware, Software, Stateful, Stateless.
• >Next-Generation Firewalls (NGFWs): Incorporate advanced features like deep packet inspection and threat intelligence.

VPN (Virtual Private Network):

• >Encrypts data and masks IP addresses for secure communication.

###Subnetting and Proxy Servers

• >Subnetting: Divides a network into logical subgroups (subnets).
• >Proxy Servers: Forward or restrict internet traffic:
  • >Forward Proxy - Controls user internet access.
  • >Reverse Proxy - Regulates external access to internal servers.

###Network Attacks

DoS and DDoS Attacks:

1. >SYN Flood - Overloads servers with SYN packets.
2. >ICMP Flood - Excessive ICMP packets disrupt services.
3. >Ping of Death - Oversized ICMP packets crash systems.

Packet Sniffing and Spoofing:

• >Passive Sniffing - Observes packets.
• >Active Sniffing - Alters packet contents.
• >IP Spoofing - Impersonates devices by faking IP addresses.

###Security Hardening

Focus Areas:

• >Hardware - Regular updates and strong physical security.
• >Operating Systems - Patch updates, strong passwords, MFA.
• >Applications - Frequent vulnerability assessments.
• >Networks - Encryption, port filtering, segmentation.

Penetration Testing:

Simulated attacks to identify vulnerabilities.

###Virtualization and Cloud Security

• >VMs and Sandboxes: Isolated environments for secure testing.
• >Cloud Hardening: Includes IAM, hypervisors, baselining, and cryptography.