12.5-6_Channel Management Flashcards
Wireless LAN devices have transmitters and receivers tuned to specific frequencies of radio waves to communicate. A common practice is for frequencies to be allocated as___. Such ***are then split into smaller ranges called ___.
ranges
channels
Frequency Channel Saturation
This is a modulation technique designed to spread a signal over a larger frequency band. Spread spectrum techniques were developed during war time to make it more difficult for enemies to intercept or jam a communication signal.
Direct-Sequence Spread Spectrum (DSSS)
Frequency Channel Saturation
__: This relies on spread spectrum methods to communicate. It transmits radio signals by rapidly switching a carrier signal among many frequency channels.
Frequency-Hopping Spread Spectrum (FHSS)
With the FHSS, the sender and receiver must be synchronized to “know” which channel to jump to
Frequency Channel Saturation
__: This is a subset of frequency division multiplexing in which a single channel uses multiple sub-channels on adjacent frequencies.
Orthogonal Frequency-Division Multiplexing (OFDM)
Sub-channels in an OFDM system are precisely _____to one another which allow the sub-channels to overlap without interfering
orthogonal
The new 802.11ax uses a variation of OFDM called ____
Orthogonal frequency-division multiaccess (OFDMA).
A best practice for WLANs requiring multiple APs is to use __ channels.
non-overlapping
When planning the location of APs, the ___ is important
approximate circular coverage area
Plan a WLAN Deployment
If APs are to use existing wiring or if there are locations where APs cannot be placed, note these locations on the ___
map
Plan a WLAN Deployment
Note all potential sources of___which can include microwave ovens, wireless video cameras, fluorescent lights, motion detectors, or any other device that uses the 2.4 GHz range.
interference
Plan a WLAN Deployment
Position APs ___ (below/ above) obstructions.
above
Plan a WLAN Deployment
Position APs _____(horizontally/ vertically) near the ceiling in the center of each coverage area, if possible.
vertically
Plan a WLAN Deployment
Position APs in locations where__are expected to be. For example, conference rooms are typically a better location for APs than a hallway.
users
Plan a WLAN Deployment
If an IEEE 802.11 network has been configured for mixed mode, the wireless clients may experience __than normal speeds in order to support the older wireless standards.
slower
Wireless networks are specifically susceptible to several threats, including:
__: Wireless data should be encrypted to prevent it from being read by eavesdroppers.
Interception of data
Wireless networks are specifically susceptible to several threats, including:
__: Unauthorized users attempting to access network resources can be deterred through effective authentication techniques.
Wireless Intruders
Wireless networks are specifically susceptible to several threats, including:
__: Access to WLAN services can be compromised either accidentally or maliciously. Various solutions exist depending on the source of the DoS attack.
Denial of Service (DoS) Attacks
Wireless networks are specifically susceptible to several threats, including:
___: Unauthorized APs installed by a well-intentioned user or for malicious purposes can be detected using management software.
Rogue APs
Wireless DoS attacks can be the result of:
__: Configuration errors can disable the WLAN. For instance, an administrator could accidently alter a configuration and disable the network, or an intruder with administrator privileges could intentionally disable a WLAN.
Improperly configured devices
Wireless DoS attacks can be the result of:
___: Their goal is to disable the wireless network completely or to the point where no legitimate device can access the medium.
A malicious user intentionally interfering with the wireless communication
Wireless DoS attacks can be the result of:
___: WLANs are prone to interference from other wireless devices including microwave ovens, cordless phones, baby monitors, and more, as shown in the figure.
Accidental interference
The ___ (2.4 GHz/ 5GHZ) band is more prone to interference than the___ (2.4 GHz/ 5GHZ) band.
2.4 GHZ
5 GHZ
A___ is an AP or wireless router that has been connected to a corporate network without explicit authorization and against corporate policy
rogue AP
TRUE OR FALSE
Anyone with access to the premises can install (maliciously or non-maliciously) an inexpensive wireless router that can potentially allow access to a secure network resource.
True
True or False
A personal network hotspot could also be used as a rogue AP.
True
For example, a user with secure network access enables their authorized Windows host to become a Wi-Fi AP. Doing so circumvents the security measures and other unauthorized devices can now access network resources as a shared device.
To prevent the installation of rogue APs, organizations must configure WLCs with___, as shown in the figure, and use monitoring software to actively monitor the radio spectrum for unauthorized APs.
rogue AP policies
To minimize the risk of a DoS attack due to improperly configured devices and malicious attacks, harden all devices, keep ___ secure, create backups, and ensure that all configuration changes are incorporated off-hours.
passwords
In a___ attack, the hacker is positioned in between two legitimate entities in order to read or modify the data that passes between the two parties.
man-in-the-middle (MITM)
A popular wireless MITM attack is called the “___” attack, where an attacker introduces a rogue AP and configures it with the same SSID as a legitimate AP. Locations offering free Wi-Fi, such as airports, cafes, and restaurants, are particularly popular spots for this type of attack due to the open authentication.
evil twin AP
Defeating an attack like an MITM attack depends on the ___of the WLAN infrastructure and the___ in monitoring activity on the network.
sophistication
vigilance
