Security And The OSI Model

Security and the OSI Model

Network security is a topic that reaches far beyond the realm of firewalls, passwords, and user ID accounts. For a network and data to remain secure there must be protective measures at each level in the OSI interconnect model. While each layer basically operates autonomously of the other it is important to ensure that the data being transmitted from the host to destination has not been tampered with or is being prevented from reaching its destination. There are seven level to the OSI interconnect model; each with its own special tasks, abilities, and weaknesses.

There are seven layers in the OSI interconnect model; they are the Physical, Datalink, Network, Transport, Session, Presentation, and Application layers. Layer one the physical layer deals with the actual physical connections to the real world. All of the wires, power cords, and hardware that make up the physical portions of a network are part of the physical layer. There are several security issues that can cause physical layer problems within a network. The easiest way to cause a denial of service would be to simply remove power or disconnect or cut an important network cable going to a crucial piece of equipment. Another security concern would be a tapping of the physical medium allowing an attacker to copy or even corrupt the data stream. The best way to prevent these types of attacks is to keep facilities secure, keep all critical areas under lock and key and perform routine audits to ensure the infrastructure is safe and secure.

The second layer in the OSI model is the data link layer; here data is transmitted and received reliably across a physical medium.

Two of the biggest threats to the data link layer have to deal...

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...efully review any new applications to ascertain whether or not a new application contains security flaws.

After looking into each of the seven layers in the OSI model it is apparent that there are many ways to exploit a security flaw within a system. A good security analyst has to look at the overall picture to keep the entire system secure and not just one or two layers. Information technology security measures are not a one time fix; it is a continuous process that must occur to keep pace with ever changing protocols, applications, and the ingenuity of attackers.

References

Reed, Damon "Applying the OSI Seven Layer Network Model to Information Security", November 2003. SANS Institute- The Information Security Reading Room.

Surman, Glenn "Understanding security using the OSI model" March 20, 2002,

SANS Institute- The Information Security Reading Room.