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Infrastructure Security: Devices and Media • Chapter 6 403

Vulnerabilities of Coax Cabling

Both types of coax cabling share some of the same vulnerabilities. Unfortunately, it
is relatively easy to perform a DoS attack on this type of network by cutting the
cable or disconnecting a device. If communication is not able to flow completely
up and down a coax network, the entire network is brought down. In addition,
since connections to the network really cannot be controlled with a switch or hub,
there is no way to prevent unauthorized connections.All an intruder has to do is
tap into the network with either a T-connector or vampire tap for thinnet or
thicknet, respectively.
These vulnerabilities are due to the topology of coax networks.A coax network
uses a bus topology, which basically means that all of the network devices are con-
nected in a linear fashion. Each device on the network completes the circuit for
the network as a whole. Due to this, if any device is removed from the network or
if there is a break anywhere in the cable, the circuit is broken and the entire net-
work is brought down.
The main advantages to coax networks are the price and the ease of implemen-
tation. Since no expensive hubs or switches are required, cost is kept low. Since all
that is required to set up the network is to run a coax cable from one computer to
the next and connect them with T-connectors, this is one of the easiest networks to
implement.
Most coax networks have been or are being replaced with unshielded twisted
pair/shielded twisted pair (UTP/STP) or fiber-optic cabling.Though you may
never work with a coax network, it is important know how vulnerable it is to dis-
ruption of service or intrusion.

TEST DAY TIP
While coax is not as commonly used as it used to be, the Security+ exam
expects you to understand how it works and when it should and should
not be used. Understanding the issues that can arise with the use of
coax, such as bringing an entire network down by removing a network
device, will help you answer these questions correctly.

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