Name Essay examples

7295 Words Oct 31st, 2013 30 Pages
Essay 16

Local Area Networks
Marshall D. Abrams and Harold J. Podell

Local area network (LAN) communications security is addressed in this essay. LANs are introduced as providing: (1) a private communications facility, (2) services over a relatively limited geographic area, (3) a high data rate for computer communications, and (4) common access to a wide range of devices and services. Security issues pertinent to LANs are discussed. For example, LANs share many security problems and approaches for their solutions with point-to-point conventional communications systems. In addition, LANs have some unique problems of their own: (1) universal data availability, (2) passive and active wiretap threats, (3) end-to-end access control, and
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This essay does not address this distributed processing within the terminals, workstations, and hosts connected to the LAN. That is another subject for another essay.

Figure 1. Seven-layer ISO protocol model.

Malicious software such as Trojan horses and worms can attack LANs. In fact, the physical distribution of any network increases the difficulty of protection. Malicious software is discussed in Essay 4. LANs connect computers, terminals, workstations, and other data terminal equipment (DTE). In this essay we will use “DTE” to refer to whatever is connected to the LAN when it is not important what function it serves. The distinction between a personal computer and a workstation is not important for the purposes of this essay. Let’s start with a functional definition. A LAN is a private communications facility, usually owned by the organization that uses it. The cost of


Information Security

using the LAN is fixed, independent of level of usage. LANs provide an opportunity for the owning organization to customize its communications capabilities in many ways, such as carrying audio, video, and data traffic; providing multiple simultaneous connections; and providing security services. A LAN generally serves a limited geographic area, such as a single building or a campus, providing a high communications rate or bandwidth and common access to a wide range of devices and services. In general, LANs may be partitioned or

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