Networking Fundamentals for Security
OSI Model
The Open Systems Interconnection (OSI) model is a conceptual framework used to understand network interactions in seven layers:
- Physical - Cables, signals, and binary transmission
- Data Link - MAC addresses, switches, frames
- Network - IP addresses, routers, packets
- Transport - TCP/UDP, ports, segments
- Session - Establishes and manages connections
- Presentation - Data translation, encryption
- Application - HTTP, FTP, SMTP, etc.
TCP/IP Protocol Suite
The TCP/IP model is the practical implementation of networking protocols:
- Application Layer (HTTP, FTP, DNS, SMTP)
- Transport Layer (TCP, UDP)
- Internet Layer (IP, ICMP, ARP)
- Network Access Layer (Ethernet, Wi-Fi)
Common Network Attacks
Man-in-the-Middle (MITM)
Attacker secretly intercepts and relays messages between two parties.
Denial of Service (DoS)
Overwhelming a system with traffic to make it unavailable.
DNS Spoofing
Redirecting traffic by corrupting DNS cache with false entries.
Network Security Tools
| Tool | Purpose |
|---|---|
| Wireshark | Network protocol analyzer |
| Nmap | Network discovery and security auditing |
| tcpdump | Command-line packet analyzer |
| Snort | Network intrusion detection system |