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Applying the OSI Seven Layer Network Model To
Information Security
This paper focuses on reviewing a key area of data networking theory - The Open Systems Interconnect (OSI)
Seven LayerNetwork Model. This paper demonstrates the application of the model's concepts into the context of information security. This paper presents the perspective that common information security problems map directly to the logical constructs presented in the OSI Seven Layer Network Model, and seeks to demonstrate the Seven Layer Model's usefulness in evaluating information security ...
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© SANS Institute 2004, As part of the Information Security Reading Room Author retains full rights.
Applying the OSI Seven Layer Network
Model To Information Security

By Damon Reed
November 21, 2003
SANS GIAC GSEC Practical Assignment version 1.4b Option One
.
© SANS Institute 2004, As part of the Information Security Reading Room Author retains fullrights.

Page 2 Applying the OSI seven-layer model to Information Security

Abstract
Data networking is a critical area of focus in the study of information security.
This paper focuses on reviewing a key area of data networking theory - The Open
Systems Interconnect (OSI) Seven Layer Network Model. This paper demonstrates the application of the model’s concepts into the context ofinformation security. This paper overall presents the perspective that common information security problems map directly to the logical constructs presented in the OSI Seven Layer Network Model, and seeks to demonstrate the Seven Layer Model’s usefulness in evaluating informationsecurity problems and solutions. The OSI Model is presented by way of both formal definition and practical terms that affectinformation security on a layer-by-layer basis.
For each layer, examples of common information security threats and controls are
evaluated by how they fit into the OSI Seven Layer Model’s layers of classification, with notes on exceptions and special cases. Once the seven layers have been covered as a basis for the discussion, it is presented that the Seven Layer Model’s scheme for interactionbetween the layers gives insight to some of the problems faced by focused, “single-layer” security solutions. To answer these problems, a multi-layer “defense-in- indepth” approach is examined by example, taken from the viewpoint of network model depth” layers rather than discrete solutions and logical or physical hardware layers. This paper concludes with some proposed extensions to the model thatcomplete the model’s application to information security problems.

Introduction to the OSI Seven Layer Model
Networking is a prime concern for information security. The ubiquitous nature of
network connectivity may let us access the world from our computer, but it also lets that same world gain access back to us in ways we may not desire. No matter how well we secure our own hosts, we are stillvulnerable if the parts of the infrastructure between our distant destinations and ourselves fall victim to intentional exploitation or unwitting mishap. Information security and data networking are inextricably linked topics.
Today’s network engineer has no choice but to be security-conscious, and the security engineer has no choice but to understand the network he is tasked to secure. [1]
Agreat deal of formalized study has been devoted to the science and methodology of designing and maintaining networks. One formal system that network engineers discuss and apply frequently is the OSI Seven Layer Model for Networking, developed by the ISO (International Standards Organization) to define a standardized method for designing networks and the functions that support them. This model...