Chapter 11 - 01 - Understand Wireless Network Fundamentals - 04_ocred_fax_ocred.pdf

Certified Cybersecurity Technician Exam 212-82 Wireless Network Security Components of a Wireless Network Access...

Certified Cybersecurity Technician Exam 212-82 Wireless Network Security Components of a Wireless Network Access HAccess Point (AP) N N V4 ARD) %+ Itis a hardware device that allows wireless communication devices to connect ’p to a wireless network via wireless standards such as Bluetooth, Wi-Fi, etc. Wireless Cards (NIC) %++ Systems connected to the wireless network require a network interface cards (NIC) to establish a standard Ethernet connection Wireless Modem *» + Itis a device that receives and transmits network signals to other units without requiring physical cabling Wireless Bridge ¢ It connects multiple LANs at the medium access control (MAC) +* (MAC) layer and is separated either logically or physically. It is used for increasing the coverage area of the wireless network Copyright © by L| All Rights Reserved. Reproduction isis Strictly Prohibited. Components of a Wireless Network (Cont’d) — Wireless Repeater Wireless Router Wireless Gateways Wireless USB Adapter O Retransmits the Q Performs the O Routes data packets Q Connects different QO existing signal functions of a router and functions as a devices to a wireless captured from a as well as a wireless wireless AP. An network in order to wireless router or AP and provides Internet connection access the Internet AP to create a new Internet access to can be shared without a computer, network various devices between multiple router, or any other stations network device E—. 4 Y Copyright © by | All Rights Reserved. Reproduction s Strictly Prohibited. Module 11 Page 1420 Certified Cybersecurity Technician Copyright © by EG-Council Prohibited. All Rights Reserved. Reproduction is Strictly Prohibited. Certified Cybersecurity Technician Exam 212-82 Wireless Network Security Components of a Wireless < Network (Cont’d) 3J Antenna QOO Converts electrical impulses into radio waves and vice versa Nl v4 Types of Antenna e Directional Antenna e @ Parabolic Grid Antenna o 0 Dipole Antenna v"v' Used for broadcasting and vv' Itis based on the principle of a v’ Bidirectional antenna, used for obtaining radio waves from a satellite dish and can pick up Wi- supporting client connections single direction Fi signals from a distance of 16 rather than site-to-site km or more. applications 0 Omnidirectional Antenna O o Yagi Antenna e @ Reflector Antennas v It provides a 360° horizontal v¥ A unidirectional antenna v These are used for radiation pattern. It is used commonly used in communications concentrating electromagnetic in wireless base stations. in the frequency band from 10 MHz energy that is radiated or to very high frequency (VHF) and received at a focal point ultra high frequency (UHF) Components of a Wireless Network The key components of a wireless network are as follows: Access point: An access point (AP) is a hardware device that uses the wireless infrastructure network mode to connect wireless components to a wired network for transmitting data. It serves as a switch or hub between a wired LAN and a wireless network. It has a built-in transmitter, receiver, and an antenna. The additional ports in the WAP help in expanding the network range and provide access to additional clients. The number of APs depends on the network size. However, multiple APs provide access to a larger number of wireless clients and, in turn, expand the range of the wireless network. The transmission range and distance that a client has to be from a wireless AP is @ maximum default value; APs transmit usable signals well beyond the default range. The distance to which a wireless AP signal is transmitted depends on the wireless standards, obstructions, and environmental conditions between the clients and the APs. The transmission range and number of devices that a WAP can connect depends on the wireless standard used and the signal interference between the devices. In the wireless infrastructure network design, multiple APs can be used to cover an extensive area, or a single AP can be used for covering a small geographical area such as buildings, homes, etc. Wireless network cards (NIC): Wireless network cards or wireless network adapters (wireless network interface cards (NICs)) are cards that locate and communicate to an AP with a powerful signal, giving network access to the users. It is required on each device to connect to the wireless network. Laptops or desktop computers generally have built-in wireless NICs or have slots to attach them. These include two types of plug- in cards. One is called a personal computer memory card international association Module 11 Page 1421 Certified Cybersecurity Technician Copyright © by EC-Council EG-Gouncil All Rights Reserved. Reproduction is Strictly Prohibited. Certified Cybersecurity Technician Exam 212-82 Wireless Network Security (PCMCIA) card and the other is a peripheral component interconnect (PCl). Laptops have slots to insert the PCMCIA plug-in cards, whereas desktop computers have internal slots to add PCl cards. The functionality of a wired and a wireless network card is similar. The difference between the two cards is that a wired network card has a port to connect over a network, whereas a wireless network card has a built-in antenna to connect over a wireless network. Typically, computers having a PCl bus or USB ports can connect to the wireless NIC. Data transmitted using an NIC provides the following features: o Customization of the computer’s internal data from parallel to series before transmission o Division of data into small blocks which incorporates sending and receiving addresses o Itinforms when to send the packets to the destination. o It delivers the packet. * Wireless modem: A wireless modem is a device that allows PCs to connect to a wireless network and access the Internet connection directly with the help of an ISP. They receive and transmit network signals to other units without a physical cable. Wi-Fi routers have the capacity to transmit an Internet service within a confined range, whereas wireless modems can be used in almost any location where a mobile phone is present. Portable devices such as laptops, mobile phones, PDAs, etc., use wireless modems to receive signals over the air, similar to a cellular network. There are various types of wireless modems. Users can choose a wireless modem based on their requirements. The common types of wireless modems include: o Cards: They are the oldest form of wireless connection. There are two types of cards, namely, data cards and connect cards, which are available from mobile providers and are used by laptops, PCs, and routers. They are small in size and easy to use. e USB sticks: They connect quickly to the internet using a wireless modem. They resemble a universal serial bus (USB) flash drive and fit easily into the USB port of a laptop. Computers require installation of special drivers and software to use them. They are portable. e Mobile hotspots e Wireless routers The following features are considered while deciding on a wireless modem: o Speed of the modem o Protocols it can support, such as ethernet, GPRS, integrated services digital network (ISDN), Evolution-data optimized (EVDO), Wi-Fi, CPCD o Frequency band 900 MHz, 2.4 GHz, 23 GHz, 5 Hz Module 11 Page 1422 Certified Cybersecurity Technician Copyright © by EC-Council All Rights Reserved. Reproduction is Strictly Prohibited. Certified Cybersecurity Technician Exam 212-82 Wireless Network Security o Radio technique such as a DSSS or frequency hopping o Total number of channels for transmitting and receiving data o Maximum signal strength o Full duplex or half duplex capability = Wireless bridge: A wireless bridge connects multiple LANs at the medium access control (MAC) layer. These bridges separate networks either logically or physically. They cover longer distances than APs. Few wireless bridges support point-to-point connections to an AP, while some support point-to-multipoint connections to several other APs. Wireless bridging helps in connecting two LAN segments through a wireless link. Two segments reside on the same subnet and look like two ethernet switches connected with a cable to all computers within the subnet. Broadcasts reach all the machines on that subnet allowing dynamic host configuration protocol (DHCP) clients in one segment to obtain the respective addresses from a DHCP server from a different segment. A wireless bridge can be used for connecting computers in one room to computers in another room without a cable. * Wireless repeater (range expanders): This device retransmits the existing signal captured from the wireless router or an AP to create a new network. It works as an AP and a station simultaneously. The clients who are too far away from the router or AP can integrate with the same WLAN via a repeater. It implies that this device extends the signal by taking it from a wireless AP and transmits it to the uncovered area. These repeaters require an omnidirectional antenna. They capture, boost, and retransmit the signals. = Wireless Router: A wireless router is a device in a WLAN which interconnects two types of networks using radio waves to the wireless enabled devices such as computers, laptops, and tablets. It functions as a router in the LAN, but also provides mobility to users. It also functions as a wireless AP and provides Internet access to various devices. Wireless routers have the ability to filter the network traffic based on the sender’s and receiver’s IP address. A wireless router provides strong encryption, filters MAC addresses and controls SSID authentication. = Wireless gateways: A wireless gateway is a key component of a wireless network. It is a device that allows Internet-enabled devices to access the network. It combines the functions of wireless APs and routers. Wireless gateways have the feature of network address translation (NAT), which translates the public IP into a private IP and DHCP. An Internet connection can be shared between multiple stations. = Wireless USB adapter: A wireless USB adapter connects different devices to a wireless network in order to access the Internet without a computer, router, or any other network device. It also supports communication links and syncs between two or more devices. There are three main varieties of a wireless adapter: o Cellular o Bluetooth Module 11 Page 1423 Certified Cybersecurity Technician Copyright © by EG-Council All Rights Reserved. Reproduction is Strictly Prohibited. Certified Cybersecurity Technician Exam 212-82 Wireless Network Security o Wi-Fi = Antenna: An antenna is a device that is designed to transmit and receive electromagnetic waves at radio frequencies. It is a collection of metal rods and wires that captures radio waves and translates them into an electrical current. It converts electrical impulses into radio waves and vice versa. The size and shape of an antenna is designed depending on the frequency of the signal they are designed to receive. An antenna that receives high frequency signals is highly focused, whereas a low-gain antenna receives or transmits over a large angle. A transducer translates the RF fields into an alternating current (AC) and vice-versa. The following are the functions of antennas: o Transmission line: Antennas transmit or receive radio waves from one point to another. This power transmission takes place in free space through the natural media such as air, water, and earth. Antennas avoid power that is transmitted through other means. o Radiator: A radiator radiates energy powerfully. This radiated energy is transmitted through the medium. A radiator is always the size of half the wavelength. o Resonator: The use of a resonator is necessary in broadband applications. Resonances that occur must be attenuated. The characteristics of an antenna are as follows: o Operating frequency band: Antennas operate at a frequency band between 960 MHz and 1215 MHz. o Transmission power: Antennas transmit power at 1200 W peak and 140 W on an average. o Typical gain: Gain is the ratio of the power input to the antenna to the power output from the antenna. It is measured in decibels relative to an isotropic antenna (dBi). The gain is generally 3.0 dBi. o Radiation pattern: The radiation pattern of an antenna is obtained in the form of a 3-dimensional plot and is generally represented in terms of two parameters, namely, elevation and azimuth. o Directivity: The directivity gain of an antenna is the calculation of radiated power in a particular direction. It is generally the ratio of the radiation intensity in a given direction to the average radiation intensity. o Polarization: It is the orientation of electromagnetic waves from the source. There are a number of polarizations such as linear, vertical, horizontal, circular, left hand circular polarized (LHCP), and right hand circular polarized (RHCP). There are six types of wireless antennas: o Directional antenna: A directional antenna can broadcast and receive radio waves from a single direction. In order to improve the transmission and reception, a Module 11 Page 1424 Certified Cybersecurity Technician Copyright © by EG-Council All Rights Reserved. Reproduction is Strictly Prohibited. Certified Cybersecurity Technician Exam 212-82 Wireless Network Security directional antenna is designed to work effectively in a specified direction. This also helps in reducing interference. o Omnidirectional antenna: Omnidirectional antennas radiate electromagnetic (EM) energy in all directions. It provides a 360° horizontal radiation pattern. They radiate strong waves uniformly in two dimensions, but the waves are usually not as strong in the third dimension. These antennas are efficient in areas where wireless stations use time-division multiple access technology. A good example for an omnidirectional antenna is the antenna used by radio stations. These antennas are effective for radio signal transmission because the receiver may not be stationary. Therefore, a radio can receive a signal regardless of its location. Advantage: e Omnidirectional antennas can deal with signals from any direction. Disadvantages: e The coverage area of an omnidirectional antenna may be limited owing to the interference of walls and other obstacles with the radiated signal. e |tis difficult for an omnidirectional antenna to work in an internal environment. o Parabolic grid antenna: A parabolic grid antenna uses the same principle as a satellite dish, but it does not have a solid dish. It consists of a semi-dish in the form of a grid consisting of aluminum wires. Parabolic grid antennas can achieve very- long-distance Wi-Fi transmissions through highly focused radio beams. This type of antenna is useful for transmitting weak radio signals over very long distances on the order of 10 miles. The design of this antenna saves weight and space, and it can receive Wi-Fi signals that are either horizontally or vertically polarized. Advantage: e This antenna is wind resistant. Disadvantages: e This antenna is expensive since it requires a feed system for reflecting the radio signals. e |n addition to the feed system, the antenna requires a reflector. Assembling of these components makes the installation time consuming. o Yagi antenna: Yagi antenna, also called as the Yagi-Uda antenna, is a unidirectional antenna commonly used in communications using the frequency band from 10 MHz to very high frequency (VHF) and ultra-high frequency (UHF). The main objectives of this antenna are to improve the gain of the antenna and to reduce the noise level of the radio signal. It has a unidirectional radiation emission and response pattern and concentrates the radiation and response. It consists of a reflector, dipole, and directors. This antenna generates an end-fire radiation pattern. Module 11 Page 1425 Certified Cybersecurity Technician Copyright © by EC-Council All Rights Reserved. Reproduction is Strictly Prohibited. Certified Cybersecurity Technician Exam 212-82 Wireless Network Security Advantages: e AYagiantenna has a good range and ease of aiming the antenna. e The Yagi antenna is directional, focusing the entire signal in a cardinal direction. This results in high throughput. e The installation and assembly of this antenna is easy and less time consuming as compared to other antennas. Disadvantage: e The antenna is very large, especially when built for high gain levels. o Dipole antenna: A dipole antenna is a straight electrical conductor measuring half a wavelength from end to end, and it is connected at the center of the radio frequency (RF) feed line. Also called a doublet, the antenna is bilaterally symmetrical; therefore, it is inherently a balanced antenna. This kind of antenna feeds on a balanced parallel-wire RF transmission line. It is used for supporting client connections rather than site-to-site applications. Advantages: e A dipole antenna offers balanced signals. With the two-pole design, the device receives signals from a variety of frequencies. Disadvantages: e Although an indoor dipole antenna might be small, an outdoor dipole antenna can be much larger, making it difficult to manage. e To achieve the perfect frequency, antennas are required to undergo multiple combinations. This can be a hassle especially in the case of outdoor antennas. o Reflector antennas: Reflector antennas are used for concentrating electromagnetic energy that is radiated or received at a focal point. These reflectors are generally parabolic. Advantages: e |f the surface of the parabolic antenna is within the tolerance limit, it can be used as a primary mirror for all the frequencies. This can prevent interference while communicating with other satellites. e The larger the antenna reflector in terms of wavelengths, the higher is the gain. Disadvantage: e Reflector antennas reflect radio signals. e The manufacturing cost of the antenna is high. Module 11 Page 1426 Certified Cybersecurity Technician Copyright © by EC-Council All Rights Reserved. Reproduction is Strictly Prohibited.