Network+ Guide to Networks Eighth Edition Chapter 6 Wireless Networking © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 1 Objectives (1 of 2) 6.1 Identify and describe various types of wireless networking characteristics 6.2 Explain the various wireless standards that support the Internet of Things 6.3 Explain 802.11 standards and innovations 6.4 Implement a Wi-Fi network © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. Objectives (2 of 2) 6.5 Secure a Wi-Fi network 6.6 Troubleshoot a Wi-Fi network © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. Characteristics of Wireless Transmissions • Wireless networks (WLANs) • Networks that transmit signals through the air via RF (radio frequency) waves • Wired and wireless signals share many similarities • Use of the same Layer 3 and higher protocols • The nature of the atmosphere makes wireless transmission different from wired transmission © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 4 The Wireless Spectrum • The wireless spectrum is the frequency range of electromagnetic waves used for data/voice communication • Spans frequency ranges or bands between 9 kHz and 300 GHz • Some bands have only a single frequency (called a fixed frequency) for that band © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 5 Channel Management • Most wireless devices implement one of two technologies: • FHSS (frequency hopping spread spectrum) • DSSS (direct sequence spread spectrum) • How each wireless standard in the 2.4 GHz range uses its allotted band: • Wi-Fi uses DSSS • Bluetooth uses FHSS • ZigBee uses DSSS • ANT+ uses a fixed frequency (does not use DSSS or FHSS) © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 6 Antennas (1 of 2) • Wireless signals originate from electrical current traveling along a conductor: • Travels from the transmitter to an antenna • Antenna emits the signal as a series of electromagnetic waves into the atmosphere • At the destination, another antenna accepts the signal and a receiver converts it back to current • Two antennas must be tuned to the same frequency in order to use the same channel © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 7 Antennas (2 of 2) • Radiation pattern • Relative strength over three-dimensional area of all electromagnetic energy that antenna sends, receives • Unidirectional (directional antenna) • Issues wireless signals along single direction • Omnidirectional antenna • Issues, receives wireless signals with equal strength, clarity in all directions • Range • Reachable geographical area © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 8 Signal Propagation (1 of 4) • Propagation • The way in which a wave travels from one point to another • LOS (line of sight) • Signal travels in straight line directly from transmitter to receiver • When obstacles are in a signal’s way, the signal may: • Pass through them • Be absorbed into them • Be subject to any of the following phenomena (see next two slides) © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 9 Signal Propagation (2 of 4) • Fading: • As signal runs into obstacles, its energy will gradually fade • Excessive fading can cause dropped connections or slow data transmission • Attenuation: • Signal weakens - Moving away from transmission antenna • Correcting signal attenuation - Increase the power of the transmission - Repeat the signal from a closer broadcast point called a wireless range extender • Interference: • Wireless signals are more vulnerable to noise - No wireless conduit, shielding • Signal-to-noise ratio (SNR) = proportion of noise to the strength of a signal © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 10 Signal Propagation (3 of 4) • Refraction • As a wave travels through objects the wave’s direction, speed, and wavelength are altered (or refracted) • Reflection • Signal bounces back toward its source • Scattering • Diffusion in multiple different directions • Diffraction • Signal splits into secondary waves © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 11 Signal Propagation (4 of 4) • Multipath signals: • Wireless signals follow different paths to destination • Advantage - Better chance of reaching destination • Disadvantage - Signal delay will result in data errors © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 12 Wireless Standards for the IoT (Internet of Things) (1 of 2) • IoT • Made up of any device that can be connected to the Internet • Personal monitoring devices • One of the fastest-growing areas of IoT • Smart home devices • Interlink devices such as locks and lights, security cameras, etc. • HAN (home area network) • Connected devices within a home create a type of LAN © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 13 Wireless Standards for the IoT (Internet of Things) (2 of 2) • WPAN (wireless personal area network) • Include short-range wireless technologies such as Bluetooth and ZigBee • PANs rarely exceed about 10 meters in any direction • Most common wireless technologies used to connect WPAN and HAN devices are discussed next © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 14 ZigBee • ZigBee: • Based on the 802.15.4 standard • A low-powered, battery-conserving wireless technology • Designed to handle small amounts of data • Ideal for use in ISM (industrial, scientific, and medical) sensors • Used in IoT devices for: - Building automation, HVAC control, AMR (Automatic Meter Reading), and fleet management © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 15 Z-Wave • Z-Wave • A smart home protocol that provides two basic types of functions: - Signaling to manage wireless connections - Control to transmit data and commands between devices • A Z-Wave network controller (called a hub) • Receives commands from a smartphone or computer and relays the commands to various smart devices on its network • Z-Wave transmissions have a range of up to 100 m per hop • Can tolerate up to four hops through repeaters © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 16 Bluetooth (1 of 2) • Bluetooth • Operates in the radio band of 2.4–2.4835 GHz • Hops between frequencies within that band to help reduce interference • Requires close proximity to form a connection • Exact distance requirements depend on the class of Bluetooth device • Before two Bluetooth devices can connect, they must be paired • Bluetooth interfaces are susceptible to a range of security risks • Bluejacking—A connection is used to send unsolicited data • Bluesnarfing—A connection is used to download data without permission © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 17 Bluetooth (2 of 2) • Table 6-2 Bluetooth power classes Class Maximum power output Typical range Purpose 1 100 mW Up to 100 m Used for industrial purposes 2 2.5 mW Up to 10 m Used for mobile devices 3 1 mW Up to 1 m Rarely used © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 18 ANT+ • ANT+ technology is based on the ANT protocol: • An ad-hoc wireless protocol operating at about 2.4 GHz • Originally developed in 2004 and is currently owned by Garmin • ANT+ gathers and tracks information from sensors typically embedded in heart rate monitors, GPS devices, and other activity monitoring devices • ANT+ can also sync data from multiple devices for the same activity • Such as a smartwatch, smartphone, bicycle computer, or fitness equipment © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 19 RFID (Radio Frequency Identification) • RFID uses electromagnetic fields to store data on a small chip (RFID tag) • Includes an antenna that can transmit and receive, and possibly a battery • Tag and reader combinations come in three general types: • ARPT (Active Reader Passive Tag) • PRAT (Passive Reader Active Tag) • ARAT (Active Reader Active Tag) • RFID is commonly used for inventory management • An RFID tag might also be embedded in a credit card • Allowing for so-called “contactless” payment © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 20 NFC (Near-Field Communication) • NFC: • A form of RFID that transfers data wirelessly over very short distances • Signal can be transmitted one way by an NFC tag, or smart tag - When employees need access to a secure area • The NFC tag collects power from the smartphone or other device by magnetic induction © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 21 Wireless USB • Based on the UWB (Ultra-Wideband) radio platform • Certified W-USB products mimic wired USB 2.0 connections • Similar speeds, security, ease of use, and compatibility • UWB radios transmit in the range between 3.1 and 10.6 GHz © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 22 IR (Infrared) (1 of 2) • IR is used primarily to collect data through various sensors • Exists just below the spectrum visible to the human eye • IR sensors are used to collect information such as: • Presence or level of liquid • Variations in reflections from skin caused by variations in blood flow • Proximity to the device • Commands from a control device © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 23 IR (Infrared) (2 of 2) © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 24 802.11 WLAN Standards (1 of 2) • WLANs work at OSI Layers 1 and 2 • Support TCP/IP higher-layer OSI protocols and operating systems • Most popular standards used by WLANs is Wi-Fi • Developed by IEEE’s 802.11 committee • Notable Wi-Fi standards: • 802.11b, 802.11a, 802.11g, 802.11n, and 802.11ac • 802.11n and later modify the way frames are used at the MAC sublayer (lower portion of the Data Link layer) • LLC sublayer is primarily concerned with multiplexing, flow and error control, and reliability © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 25 802.11 WLAN Standards (2 of 2) • Table 6-4 Technical details for 802.11 wireless standards Standard Frequency band Max. theoretical throughput Geographic range 802.11b 2.4 GHz 11 Mbps 100 m 802.11a 5 GHz 54 Mbps 50 m 802.11g 2.4 GHz 54 Mbps 100 m 802.11n 2.4 GHz or 5 GHz 600 Mbps Indoor: 70 m Outdoor: 250 m 802.11ac Wave 1 (3 data streams) 5 GHz 1.3 Gbps Indoor: 70 m Outdoor 250 m 802.11ac Wave 2 (4 data streams) 5 GHz 3.47 Gbps Indoor: 70 m Outdoor 250 m 802.1ac Wave 3 (8 data streams) 5 GHz 6.93 Gbps Indoor: 70 m Outdoor 250 m © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 26 Access Method (1 of 3) • 802.11 MAC services • Append 48-bit physical addresses to frame to identify source and destination • Same physical addressing scheme as other Ethernet networks • Allows easy combination with other IEEE networks • Wireless devices: • Not designed to simultaneously transmit and receive • Cannot prevent collisions • Use different access method than Ethernet © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 27 Access Method (2 of 3) • CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance): • Minimizes collision potential • Uses ACK packets to verify every transmission - Requires more overhead than 802.3 - Real throughput less than theoretical maximum • RTS/CTS (Request to Send/Clear to Send) protocol: • Ensures packets not inhibited by other transmissions • Efficient for large transmission packets • Further decreases overall 802.11 efficiency © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 28 Access Method (3 of 3) © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 29 Association (1 of 5) • Packet exchanged between computer and access point in order to gain Internet access • Another function of the MAC sublayer • Scanning: • Surveys surroundings for access point • Active scanning transmits special frame - Known as a probe • Passive scanning listens for special signal - Known as a beacon fame © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 30 Association (2 of 5) • SSID (service set identifier): • Unique character string identifying access point - In beacon frame information • Configured in access point • Better security, easier network management • BSS (basic service set): • Group of stations sharing an access point • BSSID (basic service set identifier) - Group of stations identifier © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 31 Association (3 of 5) • ESS (extended service set): • Group of access points connected to same LAN - Share ESSID (extended service set identifier) • Allows roaming - Station moving from one BSS to another without losing connectivity • As devices are moved between BSSs within a single ESS: • Connecting to a different AP requires reassociation • Occurs by simply moving; high error rate © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 32 Association (4 of 5) © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 33 Association (5 of 5) © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 34 IEEE 802.11 Frames (1 of 3) • Types of overhead required to manage access to an 802.11 network • ACKs, probes, and beacons • 802.11 specifies MAC sublayer frame type • Multiple frame type groups: • Management frames: association and reassociation • Control frames: medium access and data delivery - ACK and RTS/CTS frames • Data frames: carry data sent between stations © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 35 IEEE 802.11 Frames (2 of 3) © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 36 IEEE 802.11 Frames (3 of 3) • 802.11 data frame: • Four address fields - Source address, transmitter address, receiver address, and destination address • Sequence Control field - How a large packet is fragmented • Error checking and fragmentation are handled at the MAC sublayer of the Data Link layer © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 37 802.11 Innovations (1 of 4) • MIMO (multiple input-multiple output): • Multiple access point and client device antennas may issue signal to one or more receivers • Increases range and network’s throughput • MU-MIMO (multiuser MIMO): • Newer technology that allows multiple antennas to service multiple clients simultaneously • Reduces congestion and contributes to faster data transmission • Available with WAVE 2 802.11ac products © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 38 802.11 Innovations (2 of 4) • Channel bonding • Two adjacent 20-MHz channels can be bonded to make 40-MHz channel - More than doubles the bandwidth available in single 20-MHz channel • Frame aggregation: • Combine multiple frames into one larger frame • Two techniques: - A-MSDU (Aggregated Mac Service Data Unit ) - A-MPDU (Aggregated Mac Protocol Data Unit ) • Advantage: reduces overhead © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 39 802.11 Innovations (3 of 4) • Table 6-6 Maximum frame sizes using frame aggregation Wi-Fi Standard A-MSDU A-MPDU 802.11n 7935 bytes 65,535 bytes 802.11ac 11,454 bytes 4,692,480 bytes © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 40 802.11 Innovations (4 of 4) © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 41 Implementing a Wi-Fi Network • This section describes: • WLAN technologies and how to design small WLANs • How to install and configure access points and clients on larger networks © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 42 Wireless Topologies (1 of 6) • Wireless networks are not laid out using the same topologies as wired networks • Wireless topologies: • Ad hoc—Small number of nodes closely positioned transmit directly to each other • Infrastructure—A WAP (wireless access point) or AP (access point) accepts wireless signals from multiple nodes and retransmits them to the rest of the network • Mesh—Several access points work as peer devices on the same network © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 43 Wireless Topologies (2 of 6) © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 44 Wireless Topologies (3 of 6) © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 45 Wireless Topologies (4 of 6) © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 46 Wireless Topologies (5 of 6) • Centralized wireless management is made possible by a lightweight wireless protocol • Such as Cisco’s LWAPP (Lightweight Access Point Protocol) or Cisco’s CAPWAP (Control and Provisioning of Wireless Access Points) • A wireless controller can provide: • Centralized authentication for wireless clients • Load balancing • Channel management • Detection of rouge access points • Wireless technology can be used to connect two different parts of a LAN or two separate LANs © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 47 Wireless Topologies (6 of 6) © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 48 Determine the Design (1 of 4) • Home or small office network might call for only one access point: • Often combined with switching, routing functions • Connects wireless clients to LAN • Acts as Internet gateway © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 49 Determine the Design (2 of 4) • Consider the following when deciding where to install an AP: • Distance • Type and number of obstacles • Coverage • Interference • Larger WLANs warrant a more systematic approach to access point placement • Site survey: • Assesses client requirements, facility characteristics, coverage areas • Determines access point arrangement ensuring reliable wireless connectivity - Within given area © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 50 Determine the Design (3 of 4) • A thorough site survey might include: • Studying building blueprints to identify potential obstacles • Consider whether Wi-Fi access points will be used as wireless bridges to create remote wired access to the network • Determine whether certain floors require multiple APs • Measure the signal coverage and strength from other WLANS • Test proposed access point locations • Test wireless access from the farthest corners of your space • Consider the materials used in objects that aren’t always present in the environment • Consider how the wireless portions of the LAN will integrate with the wired portions © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 51 Determine the Design (4 of 4) • After site survey has identified and verified the quantity and location of access points, you are ready to install them • Must belong to same ESS and share an ESSID • Enterprise-wide WLAN design considerations • How wireless LAN portions will integrate with wired portions © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 52 Configure Wi-Fi Connectivity Devices • APs vary in which wireless standards they support, their antenna strength, and other features • Variables set during installation: • Administrator password • SSID • Whether or not the SSID is broadcast • Security options • Whether or not DHCP is used © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 53 Configure Wi-Fi Clients • Configuration varies from one client type to another • As long as an AP is broadcasting its SSID • Clients in its vicinity will detect it and offer the user the option to associate with it • On-boarding • Installing a specific program or app onto a device to give it trusted access to certain portions of the network • Off-boarding: • Removing programs that gave devices special permissions on the network • Administrators need a feature that allows them to off-board remotely (in case AP is lost or stolen) - Called a remote wipe © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 54 Wi-Fi Network Security • 802.11 standard security: • None by default • SSID: only item required • Authentication • Process of comparing and matching a client’s credentials with the credentials in a database • MAC filtering • Prevents the AP from authenticating any device whose MAC address is not listed • Encryption • Use of an algorithm to scramble data © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 55 WPA/WPA2 (Wi-Fi Protected Access) (1 of 2) • WPA • Dynamically assigns every transmission its own key • WPA2 • Replacement for WPA • A stronger encryption protocol • Most secure communication is made possible by combining a RADIUS server with WPA/WPA2 • Known as WPA-Enterprise or WPA2-Enterprise © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 56 WPA/WPA2 (Wi-Fi Protected Access) (2 of 2) • Additional security options: • Create a separate guest network through a Wi-Fi router/access point • Set up a captive portal - First page a new client sees in the browser when connecting to a guest network - Requires user to agree to a set of terms and conditions before gaining further access © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 57 Security Threats to Wi-Fi Networks (1 of 2) • War driving • A hacker searches for unprotected wireless networks by driving around with a laptop configured to receive and capture wireless data transmissions • War chalking • Hackers draw symbols with chalk on the sidewalk or wall near a vulnerable AP • To make it known to other hackers • Evil twin • A rogue AP planted in a network’s geological area to pose as an authorized AP © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 58 Security Threats to Wi-Fi Networks (2 of 2) • WPA attack: • Involves an interception of the network keys communicated between stations and APs • Also called WPA cracking • WPS attack: • Cracking a PIN in order to access an APs settings • Cracked through a brute force attack © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 59 Troubleshooting Wi-Fi Networks • Cable continuity and performance testers will tell nothing about wireless connections, stations, or APs on a network • To troubleshoot wireless LANS • You need tools that contain wireless NICs and run wireless protocols © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 60 Wi-Fi Network Tools (1 of 2) • Two types of software tools you should have: • Spectrum analyzer - Can assess the quality of the wireless signal • Wireless analyzer (Wi-Fi analyzer) - Can evaluate Wi-Fi network availability, optimize Wi-Fi signal settings, and help identify Wi-Fi security threats • List of capabilities common to wireless testing tools: • Identify transmitting access points, stations, and channels over which they are communicating • Measure signal strength from an AP © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 61 Wi-Fi Network Tools (2 of 2) • List of capabilities common to wireless testing tools (continued): • Indicate the effects of attenuation, signal loss, and noise • Interpret signal strength information • Ensure proper association and reassociation between APs • Capture and interpret traffic • Measure throughput and assess data transmission errors • Analyze characteristics of each channel © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 62 Avoid Pitfalls (1 of 2) • Wireless configuration pitfalls to avoid: • Wrong SSID • Security type mismatch • Wrong passphrase • Overlapping channels or mismatched frequencies • Mismatched standards • Incorrect antenna placement • Interference • Simultaneous wired and wireless connections • Problems with firmware updates • Unoptimized access point power levels • Inappropriate antenna type • Client saturation © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 63 Avoid Pitfalls (2 of 2) © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 64 Chapter Summary (1 of 4) • LANS that transmit signals through the air via RF waves are known as WLANs • To allow multiple devices to share the same band, the band is subdivided into channels and channels are further subdivided into narrowband channels • Propagation refers to the way in which a wave travels from one point to another • The IoT (Internet of Things) is made up of any device that can be connected to the Internet • Based on the 802.15.4 standard, ZigBee is a low-powered, battery-conserving wireless technology • Z-Wave is a smart home protocol that provides two basic types of functions: signaling, to manage wireless connections, and control, to transmit data and commands between devices © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 65 Chapter Summary (2 of 4) • Bluetooth operates in the radio band of 2.4–2.4835 GHz and hops between frequencies within that band to help reduce interference • RFID uses electromagnetic fields to store data on a small chip in an RFID tag • NFC is a form of RFID that transfers data wirelessly over very short distances • I R (Infrared) technology is used in IoT to collect data through various sensors • Wi-Fi (wireless fidelity) is a collection of wireless standards and their amendments, extensions, and corrections • Association is another function of the MAC sublayer described in the 802.11 standard • MIMO and MU-MIMO access points can only be used at full capacity when the client devices also support MIMO or MU-MIMO technology © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 66 Chapter Summary (3 of 4) • Wireless networks are not laid out using the same topologies as wired networks • Most small, wireless LANs use the infrastructure topology, requiring one or more APs • APs vary in which wireless standards they support, their antenna strength, and other features • As long as an AP is broadcasting its SSID, clients in its vicinity will detect it and offer the user the option to associate with it • Authentication is the process of comparing and matching a client’s credentials with the credentials in a client database to enable the client to log on • WPA dynamically assigns every transmission its own key • Wireless transmission are susceptible to eavesdropping © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 67 Chapter Summary (4 of 4) • Many applications can scan for wireless signals over a certain geographical range and discover all access points and wireless nodes transmitting in the area • On every type of network, many variables must be accurately set on clients, servers, and connectivity devices in order for communication to succeed © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 68 End of Chapter Discussion • What are some of the different types of wireless topologies that can be created? • Describe the 802.11a standard, and detail some of its history and advantages / disadvantages versus other 802.11 standards. • What is the difference between war driving and war chalking? © 2019 Cengage. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part, except for use as permitted in a license distributed with a certain product or service or otherwise on a password-protected website for classroom use. 69
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