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ChApTEr 5: Wireless Networking 176. The following radio frequency behaviors are important in your basic understanding of how wireless networks operate and interact with their environments.. Gain occurs when a signal has its strength increased, such as by passing through an amplifier. As you can see in the left-hand side of Figure 5.1, the lower wave represents the signal before...
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IEEE 802.11. The original IEEE 802.11 standard was developed in 1989 and defines the operation of wireless networks operating in the 2.4 GHz range using either DSSS or FHSS at the physical layer of the OSI model. The intent of the standard is to provide a wireless equivalent for standards, such as 802.3, that are used for wired networks. DSSS...
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encrypts the challenge with the secret key, and transmits the encrypted challenge back to the authenticator.. One of the greatest weaknesses in shared-key authen- tication is that it provides an attacker with enough information to try and crack the WEP secret key. The challenge, which is sent from authenticator to requestor, is sent in the clear form. The requesting client...
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If the network is encrypted, the hacker will start by determining the physical location of the target. NetStumbler has the ability to display the signal strength of the discovered networks. Utilizing this information, the attacker only needs to drive around and look for a location where the signal strength increases and decreases to determine the home of the wireless network.....
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Dur- ing this time, rogue APs can be made available operating at a higher power than the authorized APs. When the jamming attack is stopped, the clients will tend to associate back to the AP that is presenting the strongest signal.. Now the attacker owns all of the network clients attached to his rogue APs.. In some cases, you find...
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ChApTEr 5: Wireless Networking 226. sion of WEP available and keep abreast of the latest upgrades to the standards.. The IEEE 802.1x specification uses the Extensible Authentication. security principles and allows the network administrator to fully assess the risks associated with using wireless and other. Malicious users aren’t the source of all threats. be caused by a conflict of similar...
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As a matter of fact, no matter how long you are in networking, you will find the OSI model is referenced on a daily basis all the way from the beginning as a student to a networking master.. In this chapter, we look at the networking models that provide guidelines for vendors of networking products, including the early Depart- ment...
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TCP/IP protocols on the Internet and the IPX addresses used by the IPX/SPX protocols on NetWare networks are examples of logical addresses. These protocol stacks are referred to as routable because they include address- ing schemes that identify both the network or subnet and the particular client on that network or subnet. The most critical fact here is that all...
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In essence, it is the gateway between the transport layer and the session layer in the OSI model, providing a common interface developers can use to access both transport and session layer functionality.. The API is the interface through which developers can access network infra- structure services such as various application layer protocols. Dynamic Host Configuration Protocol (DHCP), DNS, and...
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name service allows host computers to attain and retain (or defend) a NetBIOS name. In addition, the name service resolves a specific NetBIOS name to an IP address. This process uses broadcast messages that are sent to all hosts on the network. Computers running UNIX, Linux, and other non-Microsoft operating systems typically use DNS for name resolution although there. Remember...
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ChApTEr 6: The OSI Model and Networking Protocols 276. The next layer, the data link layer, is where your MAC address is located. The data link layer is subdivided into two sublayers, known as the LLC and MAC layer. The LLC sublayer is responsible for providing the logic for the data link, and thus it controls the synchronization, flow control,...
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is also used to provide network communication in most of the world’s com- panies, universities, and countries. it is most likely that TCP/IP is in use. By the end of this chapter, you should be comfortable with navigating numbering schemes, have a better understanding of the protocol suite, and can work your way through any problem presented to you (on...
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the number is 1. After nine, you move to the next position, set it to 1 and reset the first position to 0, resulting in the decimal number 10. For instance, to represent the number 128, we would set the eighth position, or bit 7 (remember, we’re counting from 0 to 7, not 1 to 8), to 1. What if...
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The network would come to a grinding halt from all that traffic. Because the network ID is a fixed number assigned by the InterNIC, a method was devised to subdivide the assigned network ID by borrowing bits from the host address space, not the network address space. A subnetted Class A network might use bits from the second and third...
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Creating the Subnet Mask. We’ve determined our subnets, and now we need to create a subnet mask that will work with each subnet ID we created. Recall that we use bitwise ANDing to compare the bits of the IP address and the subnet mask. The result of the comparison is the network ID. Using Table 6.16, we know that we...
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ChApTEr 7: TCP/IP and Routing 326. Remember, each host on the network needs a unique IP address to be able to commu- nicate. When an organization sets up its computer users with a connection to the Internet, an IP address must be assigned to each machine. Without DHCP, the IP address must be entered manually at each computer and, if...
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After a sending host receives the needed IP address, the packet is sent from the host through the TCP/IP suite to the physical medium for delivery at the target IP address. Routing is the process of send- ing the packet to its destination. When the sending host has a packet ready, it already has determined the destination’s IP address by...
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ChApTEr 7: TCP/IP and Routing 346. identifiers of a number of private hosts to be multiplexed into the transport identifiers of a single global IP address. PAT allows numerous hosts from the internal network to share a single external network IP address. The advan- tage of this type of translation is that only one global IP address is needed, whereas...
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You have a DHCP server that is configured to have only 10 addresses available in the pool of addresses to be handed out. What might be the potential cause of the issue?. After reading this chapter, you will also understand the basic charac- teristics of specific WAN technologies, such as how packet switching and circuit switching differ.. wide Area Networking....
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366 ChApTEr 8: Wide Area Networking. MPLS is a new WAN technology that is becoming very popular because of its many benefits, including its pure Layer 3 design and the fact that it is IP-based. Furthermore, MPLS allows you to label data to have a specific pri- ority based on the application type. MPLS is able to use labels to...