CG: Net+ 007 - 8: Wireless Technologies
RC4 (which stands for "Ron's Code" or__________ because it was developed by __________of RSA Security)
"Rivest Cipher" , by Ron Rivest
The other day, I was bringing a new AP online without a wireless controller. The first thing I did was to assign the AP an IP address. To do so, I established a 1 ___________ connection into the AP through the 2 __________________ and configured the 3 ________ to give the AP a 4 ___________
1 Telnet serial connection 2 console port 3 CLI 4 static IP address.
The primary advantage of a wireless controller is that you just plug the AP into the controller, which then 1 ______________ If you want to make changes—for example, change the quality of service (QoS) parameters—to all your APs, you can do so 2 ___________________.
1 which then automatically finds and configures the AP. 2 centrally instead of reconfiguring each AP individually.
What are the 4 improvements of WPA vs WEP?
1. Enterprise mode 2. Temporary session keys 3. TKIP+RC4 vs just RC4 for enhanced ecryption 4. Message Integrity Check
What are the four design factors when selecting an antenna?
1. Required distance 2. Pattern of coverage (sphere, one-direction, etc) 3. Indoor or Outdoor 4. Avoiding interference with other APs
What are the 4 design goals to keep in mind when selecting an antenna for enterprise class wireless APs?
1. Required distance between an AP and a wireless client. 2. Pattern of coverage area. 3. Indoor or outdoor environment. 4. Avoiding interference with other APs.
A common WLAN design recommendation is to have a _____% to _____% overlap of coverage between adjoining cells.
10% to 15%
When it comes to channel overlap, WLAN design recommendation is to have a ____% to ____% overlap of coverage between adjoining cells.
10% to 15%
802.11b supports speeds as high as ..?
11 Mbps
802.11n have speed ratings in the _________ to ___________ range.
130 Mbps to 150 Mbps
The 2 GHz band is actually between what two frequencies?
2.4 GHz and 2.5 GHz
What frequency band does 802.11n operate in?
2.4 Ghz and 5Ghz simultaneously
Older microwave ovens, which might not have sufficient shielding, can emit relatively high-powered signals in the____________band,
2.4GHz
Two of these bands are commonly used for WLANs. Specifically, WLANs use the range of frequencies in the _____________ range (commonly referred to as the 2.4GHz band) or in the ________________ range (commonly referred to as the 5GHz band).
2.4GHz-to-2.5GHz or 5.725GHz-to-5.875GHz
Consider, for example, the 2.4GHz band. Here, channel frequencies are separated by 5MHz (with the exception of channel 14, which has 12MHz of separation from channel 13). However, a single channel's transmission can spread over a frequency range of ___________ MHz.
22MHz.
What's the maximum bandwidth for 802.11ac?
3 Gbps
What's the maximum bandwidth for 802.11n?
300 Mbps
the speed of an 802.11n network could exceed ______ Mbps through the use of __________
300 Mbps via channel bonding
If one antenna has __________db more gain than another antenna, it has approximately twice the effective power.
3db
What frequency band does 802.11a use ?
5 GHz
In the 2,4 band, channels are separated by ___ MHz.
5 MHz
Next, I connected to the AP with an Ethernet cable and brought up the 5 ____________. I then went through the express setup to configure the AP parameters. I used the wireless interface to turn on the radios and used the network interface to turn on SNMP so that I could centrally manage the AP. The entire process took me approximately 90 minutes although I was quicker with the next AP)!
5 web GUI
The 5 GHz band is actually between what two frequencies?
5.725 GHz and 5.875 GHz
802.11a supports speeds as high as ?
54 Mbps
802.11g supports speeds as high as ..? What frequency band does it operate in?
54 Mbps / 2.4
What's the max indoor/outdoor range for 802.11n and 802.11ac?
70 M indoors / 250 M outdoors
What is the MHZ width for a single stream of 802.11ac?
80 MHz
Which 802.11 (besides the original has the lowest indoor/outdoor range?
802.11a
802.11g is backwards compatible with ?
802.11b
What technology is used to allow wireless users to authenticate to a wireless AP using their own credentials in an enterprise environment?
802.1x with RADIUS as the authentication server
What's an ESSID?
A SSID shared among multiple APs in a WLAN.
What's a mesh cloud?
A bunch of wireless devices not using centralized management
What is a rogue access point?
A malicious user could set up their own AP to which legitimate users would connect.
The main goal of EAP is to authenticate the supplicant and provide the supplicant and authentcator a _______________ during a single session.
A session key
What does WPA2 use for encryption
AES
What does AES stand for?
Advanced Encryption Standard
What does WPA3 use for encryption?
Advanced Encryption Standard
For scalability and performance reasons, WLANs might include multiple APs. Why is that?
All wireless devices associating with a single AP share a collision domain.
What is VLAN pooling?
Assigning IP addresses to clients from a pool of IP subnets and their associated VLANs
What's the difference between BSS and ESS?
BSS is a WLAN using just one AP. ESS is a WLAN using two or more APs
Why do they call channel bonding "40MHz mode"?
Because each band is 20 MHz.
Some literature refers to channel bonding as 40MHz mode. Why is that?
Because it reference the bonding of two adjacent 20MHz bands into a 40MHz band
WEP can be cracked with which attack type? Why?
Brute force, because it uses a static string of characters
If the SSID is disabled, how can a knowledgeable user still determine the SSID?
By capturing and analyzing packets
What does WPA2 use for integrity checking?
CCMP
What does CCMP stand for?
Cihper Block Chaining Message Authentication Code Protocol
What are examples of non-device objects that can cause wireless interference?
Concrete walls, metal studs, and window film.
There are two protocols used to communicate between an AP and a WLC. What's the newer one?
Control and Provisioning of Wireless Access Points (CAPWAP)
What does CCMP stand for?
Counter Mode with Cipher Block Chaining Message Authentication Code Protocol
If the Network+ exam mentions "CCMP-AES", what are they referring to?
Counter Mode with Cipher Block Chaining Message Authentication Code Protocol for integrity checking along with Advanced Encryption Standard for encryption.
802.11 uses what spread spectrum transmission method?
DSSS
Which spread spectrum transmission method is subject to environmental factors?
DSSS
What are the names of three spread spectrum variations?
DSSS FHSS OFDM
The 802.11b standard uses the 2.4GHz band and uses the ______________ method.
DSSS transmission
What does DSSS stand for?
Direct Sequence Spread Spectrum
Which spread-spectrum technology uses random chips (symbols) of data at a high transmissiom rate?
Direct-sequence spread spectrum (DSSS):
802.1X works in conjunction with what protocol to perform its job function of authentication?
EAP (Extensible Authentication Protocol)
Which spread spectrum transmission method does 802.11g use?
Either OFDM or DSSS
Which mode of WPA2 uses a server for authentication?
Enterprise mode
IEEE 802.1X works in conjunction with a specific type of protocol to perform its job of authentication. What type of protocol does IEEE 802.1X work with?
Extensible Authentication Protocol (EAP)
Which spread-spectrum technology uses pre-determined frequency switching during wireless transmissions?
Frequency-hopping spread spectrum (FHSS):
The strength of electromagnetic wave emitting from an antenna is referred to as ..?
Gain
With the increased use of wireless, both coverage and capacity-based planning should be done to provide acceptable goodput. What is goodput?
Goodput refers to the number of useful information bits that the network can deliver (not including overhead for the protocols being used).
WLANs can be categorized based on their use of wireless APs. What are the three main categories based on their use of APs?
IBSS (Independent Basic Service Set) BSS (Basic Service Set) ESS (Extended Service Set)
What separates IBSS from BSS and ESS?
IBSS WLAN operates in ad hoc mode.
Why is a PSK (preshared key) not scalable in an enterprise environment?
If the key was discovered, all the devices in the enterprise environment would have to be reconfigured, causing a lot of administrative overhead.
WEP's RC4 approach to encryption uses a 24-bit string of characters added to transmitted data, such that the same plain text data frame will never appear as the same WEP-encrypted data frame. What is this string of characters called?
Initialization Vector
802.11a never gained widespread adoption because..?
It wasn't backwards compatible with 802.11b
How many UTP wires are needed in a wireless mesh connection?
Just one. One node connected to a modem. All additional infrastructure devices communicate with each other and or that node wirelessly.
There are two protocols used to communicate between an AP and a WLC. What's the older one?
Lightweight Access Point Protocol (LWPP)
Besides administrative overhead, what is another drawback to MAC filtering as a security method?
MAC addresses can be falsified.
802.11n uses the _________ transmission method.
OFDM
What spread spectrum transmission method does 802.11n use?
OFDM
What spread spectrum variant does 802.11a use?
OFDM
Which spread spectrum variant is best for resisting interfernce and supports high data rates?
OFDM
802.11g can use either the _____ or the ___________ transmission method.
OFDM or DSSS
The 802.11a standard uses the 5GHz band and uses the ___________________ method.
OFDM transmission method.
The two types of coverage area antennas are?
Omnidirectional and Unidirectional
What is an example of an ad hoc WLAN?
One laptop communicating to another laptop with a wireless card.
What does OFDM stand for?
Orthogonal Frequency Division Multiplexing
Which spread-spectrum technology uses random chips (symbols) of data at a lowertransmissiom rate while resisting interference between the various data streams?
Orthogonal frequency-division multiplexing (OFDM):
What does WEP use as its encryption algorothim?
RC4
RC4 is also known as
Rivest Cipher
Why would you want to integrate a RADIUS server with Microsoft Active Directory?
So you don't have to recreate every user account.
What else besides WEP uses RC4 for encryption algorithim?
TKIP
One of the improveents of WPA vs WEP is Message Integrity Ceck. What is that?
TKIP leverages Message Integrity Check (MIC) which can confirm that data was not modified in transit.
What is gain?
The strength of the electromagnetic waves being radiated from an antenna.
Where would you use a wireless mesh connection?
They are convenient where Ethernet wall connections are lacking -- for instance, in outdoor concert venues, warehouses or transportation settings.
802.11n can use channel bonding. How does that work?
Two wireless band are logically bonded together, forming a band with twice the bandwidth of an individual band.
IEEE 802.11 refers to what?
WPA2
What is WPA2 "enterprise mode"?
WPA2 that uses a centralized server for authentication.
What is WPA2 "personal mode"?
WPA2 that uses a configured password or PSK instead of a centralized server.
Which WLAN security threat involves symbols?
War chalking
What turns a rogue access point into an evil twin?
When the rogue access point is configured with the SSID of a legitimate AP.
Which nonprofit organization developed its own security standard, WPA, to address the weaknesses of WEP?
WiFi Alliance
How does 802.11n's channel bonding work?
With channel bonding, two wireless bands are logically bonded together, forming a band with twice the bandwidth of an individual band.
RC4 uses a 24-bit initialization vector (IV). What is this?
a string of characters added to the transmitted data, such that the same plain-text data frame will never appear as the same WEP-encrypted data frame
IEEE 802.1x is a technology that allows wireless clients to authenticate with an ...?
an authentication server
The process through which a wireless client (for example, a laptop or a smartphone) attaches with a wireless router (or wireless AP) is called ___________.
association.
The 24-bit initialization vector (IV) is transmitted in clear text. How can this be exploited by a hacker?
because a malicious user can see the 24-bit initialization vector in clear text if they use packet-capture software and capture enough packets having the same WEP key, they can use a mathematical algorithm to determine the static WEP key (which can be performed with WEP-cracking software found on the Internet).
When does the random back-off timer kick in for CSMA/CA?
before a potential collison
The strength of the electromagnetic waves being radiated from an antenna is referred to as gain, which involves a measurement of
both direction and efficiency of a transmission
802.11n can hit speeds higher than 300 Mbps with the use of?
channel bonding
Within each band are specific frequencies at which wireless devices operate. These specific frequencies are known as ?
channels
Conversely, the gain measurement for a wireless AP's antenna receiving a signal is a measurement of how efficiently the received electromagnetic waves arriving from a specific direction are ________________?
converted back into electricity leaving the antenna
For example, the gain measurement for a wireless AP's antenna transmitting a signal is a measurement of how efficiently the power being applied to the antenna is ____________________?
converted into electromagnetic waves being broadcast in a specific direction.
Antennas are classified by their gain and ________.
coverage area
Gain is commonly measured using the ________ unit of measure.
dBi
MIMO uses multiple antennas for transmission and reception. These antennas do not interfere with one another, thanks to MIMO's use of spatial multiplexing. How does spatial multiplexing work?
data is encoded based on the antenna from which the data will be transmitted.
Gain is measured in ...
dbi
In the dbi unit of measure, the dB stands for _______ and the i stands for _________
decibels and isotropic
Personally, I think that if you have more than _______________ APs , investing in a wireless LAN (WLAN) controller is worth the cost, just from a management and maintenance perspective.
four or five APs
Are WLAN connections half-duplex or full-duplex?
half-duplex
The frequencies in a spread spectrum transmission are so close to each other, they are referred to as a _______________ transmission.
narrowband
The two broad categories of antennas, which are based on coverage area, are ________ and _______________.
omnidirectional and unidirectional:
In electromagnetic theory, radio waves cannot propagate through a __________________
perfect conductor.
Frequencies used for various wireless channels are considered to be the center frequencies of a channel. In actual operation, a channel uses more than one frequency. This transmission method is called...?
spread spectrum
In the previous discussion, you saw the frequencies used for various wireless channels. However, be aware that those frequencies are considered to be the center frequencies of a channel. In actual operation, a channel uses more than one frequency, which is a transmission method called _______________
spread spectrum.
Although there are some country-specific variations, certain frequency ranges (or frequency bands) have been reserved internationally for industrial, scientific, and medical purposes. These frequency bands are called _______________.
the ISM bands
an overlap of coverage between APs should exist to allow uninterrupted roaming from one WLAN cell to another. What is a cell?
the coverage area provided by an AP
The protocols used to communicate between an AP and a WLC could be the older Lightweight Access Point Protocol (LWAPP) or
the more current Control And Provisioning of Wireless Access Points (CAPWAP).
Antennas are classified not just by their gain but also by ___________________.
their coverage area
Not only does metal objects (near perfect conductors) limit the range of the WLAN signal, but radio waves carrying data might __________ . This __________ issue can cause data corruption.
travel over different paths. multipath
What does polarity of an antenna refer to?
two AP's match vertical or horizontal alignment with antennas
Although a honeycomb channel assignment scheme can be used for the 5 GHz band, identical channels should be separated by at least _________ cells for the 2.4 GHz band.
two cells
Which antenna coverage area type is better suited to avoid potential interfernces?
unidirectional
Which antenna coverage area type reaches further distances?
unidirectional
Why is WEP and WPA considered poor security options for a wireless network?
utilities are available on the Internet for cracking each of these approaches to wireless security
To manage multiple APs, a company will use a __________________ for centralized management and control of the APs.
wireless LAN controller (WLC)
enterprise-class WLANs, and even most WLANs in homes, are configured in such a way that a wireless client connects to some sort of a wireless base station, such as a ____________ or a __________________.
wireless access point or wireless router
To manage multiple APs, a company will use a ...
wireless lan controller (WLC)
