Networking is the Foundation
Cybersecurity fundamentally relies on understanding how data moves across networks. The Open Systems Interconnection (OSI) Model is a conceptual framework used to describe network communication functions.
The 7 Layers of the OSI Model
| Layer # | Layer Name | Function (PDU) | Security Relevance |
|---|---|---|---|
| 7 | Application | User interaction (Data) | Web applications, email security, user authentication. |
| 6 | Presentation | Data format, encryption (Data) | SSL/TLS encryption implementation. |
| 5 | Session | Managing connections (Data) | Session hijacking prevention. |
| 4 | Transport | Reliable data transfer (Segments) | Port security, TCP/UDP security. |
| 3 | Network | Routing data (Packets) | IP addresses, routing protocols, firewalls. |
| 2 | Data Link | Physical addressing (Frames) | MAC addressing, ARP security, Layer 2 switches. |
| 1 | Physical | Transmission medium (Bits) | Cabling, signal encoding, physical security. |
Memorization Tip: Please Do Not Throw Sausage Pizza Away (Physical to Application).