Networking Fundamentals

Master network protocols, architecture, and security fundamentals essential for cybersecurity professionals.

OSI Model
TCP/IP
Network Security
Packet Analysis

OSI vs TCP/IP Models

Understand the fundamental network models that govern how data flows across networks.

OSI Model (7 Layers)

The Open Systems Interconnection model provides a conceptual framework for network communication.

7. Application
HTTP, FTP, SMTP
6. Presentation
SSL, TLS, JPEG
5. Session
NetBIOS, RPC
4. Transport
TCP, UDP
3. Network
IP, ICMP, ARP
2. Data Link
Ethernet, MAC
1. Physical
Cables, Hubs

TCP/IP Model (4 Layers)

The practical implementation model used in modern networks and the internet.

4. Application
HTTP, FTP, DNS
3. Transport
TCP, UDP
2. Internet
IP, ICMP
1. Network Access
Ethernet, WiFi

Subnetting & Network Address Translation

Master IP addressing, subnetting, and NAT concepts essential for network design and security.

Subnetting Fundamentals

Divide networks into smaller, manageable segments for better organization and security.

Key Concepts:

  • • Subnet Mask (e.g., 255.255.255.0)
  • • CIDR Notation (e.g., /24)
  • • Network Address
  • • Broadcast Address
  • • Host Range

NAT Types

Network Address Translation allows private IPs to communicate with public networks.

NAT Types:

  • • Static NAT (1:1 mapping)
  • • Dynamic NAT (pool-based)
  • • PAT/NAT Overload (many:1)
  • • Port Forwarding

Security Implications

How subnetting and NAT affect network security and monitoring.

Security Benefits:

  • • Network segmentation
  • • Traffic isolation
  • • IP address hiding
  • • Access control
  • • Monitoring boundaries

TCP vs UDP Protocols

Understand the fundamental differences between connection-oriented and connectionless protocols.

TCP (Transmission Control Protocol)

Connection-oriented protocol with guaranteed delivery and error checking.

Characteristics:

  • • Connection-oriented (3-way handshake)
  • • Reliable delivery
  • • Error checking and correction
  • • Ordered packet delivery
  • • Flow control
  • • Congestion control

Common Applications:

  • • HTTP/HTTPS (Web browsing)
  • • FTP (File transfer)
  • • SSH (Secure shell)
  • • SMTP (Email)
  • • Telnet

UDP (User Datagram Protocol)

Connectionless protocol with no guarantee of delivery or ordering.

Characteristics:

  • • Connectionless (no handshake)
  • • Unreliable delivery
  • • No error checking
  • • No packet ordering
  • • No flow control
  • • Faster transmission

Common Applications:

  • • DNS (Domain queries)
  • • DHCP (IP assignment)
  • • SNMP (Network management)
  • • Streaming media
  • • Online gaming
  • • VoIP

Packet Capture & Analysis

Learn to capture, analyze, and interpret network traffic for security monitoring and troubleshooting.

Wireshark

The industry-standard network protocol analyzer for packet capture and analysis.

Key Features:

Real-time packet capture
Protocol dissection
Advanced filtering
Statistical analysis
Export capabilities

tcpdump

Command-line packet analyzer for Unix-like systems.

Common Commands:

tcpdump -i eth0
tcpdump port 80
tcpdump -w capture.pcap
tcpdump host 192.168.1.1

Analysis Techniques

Methods for analyzing captured network traffic for security insights.

Analysis Methods:

Protocol Analysis

Examine packet headers and payloads

Traffic Patterns

Identify normal vs anomalous behavior

Performance Analysis

Measure latency, throughput, errors

Security Monitoring

Detect attacks and suspicious activity

Security Applications

How packet analysis supports cybersecurity operations.

Security Uses:

Intrusion detection
Malware analysis
Network forensics
Vulnerability assessment
Compliance monitoring

Essential Network Protocols

Master the key protocols that power modern networks and their security implications.

DNS

Domain Name System - translates domain names to IP addresses.

Port 53
UDP/TCP
Recursive
Iterative

DHCP

Dynamic Host Configuration Protocol - automatically assigns IP addresses.

Port 67/68
UDP
DORA Process
Lease Time

ARP

Address Resolution Protocol - maps IP addresses to MAC addresses.

Layer 2
Broadcast
Cache
Spoofing Risk

ICMP

Internet Control Message Protocol - network diagnostics and error reporting.

Ping
Traceroute
Error Messages
Flood Attacks