Introduction to the OSI Model

OSI Model

A conceptual framework dividing network communication into seven layers to simplify understanding and managing network interactions.

Defense in Depth

A layered security approach that involves securing each OSI model layer to create multiple lines of defense against cyber-attacks.

Encapsulation

The process in the OSI model where each layer adds its header (and sometimes a trailer) to the data packet as it moves from the application layer down to the physical layer for network transmission.

Decapsulation

The reverse process of encapsulation, where each layer's header (and trailer if present) is removed as data ascends from the physical layer to the application layer for data reception.

Headers and Trailers

Header is data added at the beginning of a packet for routing and delivery, while a trailer is sometimes added at the end for error checking and data integrity.

Network Protocols

Rules that help computers send and receive information in a common language, ensuring effective communication between sender and receiver.

Port Numbers

Specific destination points for communication, ensuring messages reach the correct service on a server, categorized into Well-Known Ports (0-1023) and Registered Ports (1024-49151).