chapter 4 part 2 Flashcards
what is an Autonomous AP?
a stand-alone wireless device that has to be configured manually. multiple ones can be controlled using a WDS: wireless domain service or cisco wireless lan solution engine.
what are controller based AP’s?
controller based access points: wireless devices that depend on a server that is connected to the network and provides all the configurations for the Access point.
MCC?
Meraki Cloud Controller: cloud based service, monitors and reports behavior of network. used to manage wireless AP’s.
cisco Unified wireless network architecture? is what?
software that is used to control several wireless access points. The controller has all of the intelligence for communication and the AP is a “dumb terminal” that simply processes packets.
what kind of antenna is this:
Omnidirectional Wi-Fi Antennas
basic dipole antennas, also referred to as “rubber duck” design, similar to those used on walkie-talkie radios. Omnidirectional antennas provide 360-degree coverage and are ideal in open office areas, hallways, conference rooms, and outside areas
what kind of antenna is this: Directional Wi-Fi Antennas
focus the radio signal in a given direction. This enhances the signal to and from the AP in the direction the antenna is pointing, providing stronger signal strength in one direction and less signal strength in all other directions.
what kind of antenna is this: Yagi antennas
long-distance Wi-Fi networking. These antennas are typically used to extend the range of outdoor hotspots in a specific direction, or to reach an outbuilding.
AD hoc mode is what?
when 2 devices connect wirelessly without a wireless access point. (Bluetooth and wi-fi direct). smartphones can also provide wireless hotspots using ad hoc mode.
what is infrastructure mode?
when clients connect to a wireless router/ AP that is part of a WLAN.
BSS?
Basic Service Set: a single AP connecting all associated clients. (wireless 802.11)
BSA?
Basic Service Area: this is when the topology BSS (Basic Service Set) is used for clients to gain wireless access and the BSA is the wireless coverage area.
BSSID?
Basic Service Set Identifier: the AP layer 2 MAC address is used to identify each AP, this is the basic service set (BSS) individual device id.
ESS?
Extended Service Set: 2 or more BSS’s are joined together through a common (DS) Distribution system (same link) to provide a larger coverage area or larger BSA (Basic service area). Each ESS has its own SSID.
ESA
Extended Service Area: when 2 or more AP’s are connected and then the basic service area of each device becomes an extended area.
the AD Hoc mode for 802.11 is known as what abbreviation?
IBSS: Independent Basic Service Set
what does the frame control field do in the 802.11 wireless frame?
identifies the wireless frame, contains sub fields for protocol version.
frame control fields are?
protocol version, frame type and subtype, tods and fromds (direction of frame), more fragments, retry, power management, more data, security, reserved.
is wifi full duplex or half duplex?
half duplex and CSMA/CA is necessary
DCF?
Distributed Coordination Function (DCF: Using DCF, a wireless client transmits only if the channel is clear. All transmissions are acknowledged; therefore, if a wireless client does not receive an acknowledgment, it assumes a collision occurred and retries after a random waiting interva
DSSS?
Direct-sequence spread spectrum: spreads a RF signal over a larger channel and mixes it using a special coe. the code is used to un-mix the signal once received. this helps keep signals clear when using high demand RF ranges. 802.11b
FHSS?
Frequency-hopping spread spectrum: the Frequency changes and both the sending client and AP know that the frequency changes. This keeps RF congestion down.
OFDM?
Orthogonal frequency-division multiplexing : uses sub-channels in the RF range used by 802.11a/g/n/ac
what is the best method to set AP channels when 2 or more devices are close to one another to stop interference?
make sure the channels are set 5 channels apart or if using more than 2 devices do channels: 1,6,11.
802.11n uses the 5GHZ along with the other channels and has more channels available.
what is channel bonding and which 802.11 can use it?
802.11n uses this: 2 RF channels are combined and allow increase in throughput by using both channels at the same time.
when building an ESS (extended service set) what parameters should be planned for?
used when 2 or more AP’s are joined together as 1 seamless wireless access point. * the BSA’s of each AP should overlap by 15%, they should be on separate RF channels such as 1 and 6.
what is the passive mode on a AP?
the AP sends out its SSID and security settings in beacons to potential clients as a Broadcast
what is active mode on an AP?
wireless clients send a probe requesting a connection. the clients must know the SSID and password info.
how does a CTS attack work and what does it do?
CTS: Clear to send: used by CSMA/CA normally. the attacker floods the network/ airwaves, sending a CTS broadcast to a fake STA (Station/ access point) this tells all devices to stop transmitting on the network because it is about to send data.
MFP?
Management Frame Protection: cisco, protects against device and frame spoofing, attackers signature are matched and so the CTS (Clear to send) DOS attack does not work b/c devices know its an attack.
what is RTS?
Request to send: used by wireless devices in the CSMA/CA protocol. handshake takes place before data is sent to avoid collisions,
how do Rouge access points work? how to protect against this?
an intruder connects a wireless device/ AP to the network inside the building essentially leaving an open door for connections.
or.. employees use a connected computer to create its own PSN (personal area network) where UN-otherised devices can connect through there work pc.
((special software is used to detect UN-authorised wifi spectrum’s being used/ spoofed mac addresses.
what is MITM attack>?
man in the middle:
IPS?
intrusion prevention system: special enterprise tools. scanners for rouge AP”s.
what is the most secure wifi available?
WPA2 Enterprise: uses a server to authenticate each device and encrypts sessions with AES.
