Networking Fundamentals for Digital Forensics | Chapter 11 from Learn Computer Forensics by William Oettinger

In a world where almost every digital crime involves a network, understanding networking is critical for any forensic analyst. Chapter 11 of Learn Computer Forensics (Second Edition) by William Oettinger provides a foundational overview of networking concepts—from the OSI model to IP addressing and common communication protocols—equipping investigators with the knowledge needed to trace, analyze, and interpret network-based digital evidence.

📺 Watch the full chapter summary here:

The OSI and TCP/IP Models: Understanding Data Flow

Oettinger begins with the OSI (Open Systems Interconnection) Model and TCP/IP Model—two frameworks for understanding how data travels across a network:

• OSI Model: 7 layers – Physical, Data Link, Network, Transport, Session, Presentation, Application
• TCP/IP Model: 4 layers – Link, Internet, Transport, Application

Mapping these models is essential to pinpointing where data issues occur, identifying intrusion points, and analyzing how attacks are executed on specific protocol layers.

IP Addressing and Subnetting

Oettinger explores IP addressing in detail:

• IPv4 vs. IPv6 – Address length, format, and allocation differences
• Public vs. Private IPs – How they impact traceability and network forensics
• Subnetting and CIDR notation – Organizing networks for better efficiency and security
• NAT (Network Address Translation): Mapping multiple private addresses to a single public IP

Understanding these fundamentals helps forensic analysts identify the origin and destination of network activity during investigations.

Analyzing Network Hardware

The chapter also covers essential hardware components involved in network forensics:

• Routers: Direct network traffic between subnets and across the internet
• Switches: Facilitate communication within local networks
• Firewalls and gateways: Filter, monitor, and secure traffic at various points

Forensic investigators often examine logs and configurations from these devices to track breaches or suspicious activity.

Protocols and Communication Forensics

Chapter 11 introduces core internet protocols and their forensic significance:

• HTTP/HTTPS: Web traffic (secured and unsecured)
• FTP: File transfer activity
• SSH: Secure shell connections often used in remote access or exploitation
• DNS: Domain resolution that can be tracked to reveal visited websites
• DHCP: Dynamic IP assignment logs useful for correlating sessions with devices

Port numbers and protocol behavior help analysts determine which services were used and which applications were active during an incident.

Diagnostics and Packet Analysis

Network diagnostics and packet behavior are essential in tracing attacks and verifying connectivity:

• ICMP (ping, traceroute): Used for network testing and identifying unreachable nodes
• ARP (Address Resolution Protocol): Matches IP addresses to MAC addresses
• Encapsulation and de-encapsulation: Examining how data is packaged and unwrapped at each network layer

These insights allow forensic professionals to trace the path of malicious packets, verify spoofed addresses, or detect unauthorized communication.

Conclusion

Chapter 11 provides the networking knowledge every digital investigator needs. Whether analyzing a simple intrusion or unraveling a complex data breach, understanding how data flows through networks—down to individual ports and protocols—is vital for accurate, defensible forensic reporting.

🧠 Ready to strengthen your network forensics skills? Watch the complete video summary to learn the OSI model, IP structures, and key diagnostic tools in action.

📘 For more chapters on digital evidence, OSINT, malware analysis, and forensic imaging, explore the entire Learn Computer Forensics playlist.

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