Wireless and Broadband Net Access and Security (Lesson 11 ) Flashcards
802.11 Frame Structure - Frame Control Field
Protocol Version: allows different versions of protocol to be used in same cell at the same time
Type: Data, control, or management frame
Subtype: RTS (request to send) or CTS (clear to send)
To/From DS: frame sent to/from intercell distribution system
MF: More fragments to follow
Retry: retransmission of a frame sent earlier
Pwr: power management, put device in/out of sleep state
More: additional frames follow
W: body had been encrypted using WEP
O: sequence of bits with this set must be processed in order.
WAP
Wired Access Point
Designed for systems w/ slow processors, limited memory, or lower bandwidth.
WTLS
Wireless Transport Layer Security
WTLS (3 different classes of authentication)
Class 1: Does not allow either the client or gateway to authenticate the other
Class 2: Allows the client to authenticate the gateway
Class 3: Allows both client and gateway to authenticate each other.
WTLS Class 2 Authentication
Prior to sending a request for a session, the WAP device sends a request for authentication to the gateway. The client always initiates this process. The client can also challenge the gateway again at any time during the session.
The gateway sends a copy of its certificate, which contains the gateway’s public key.
The device receives the certificate and key and generates a unique random value for encryption.
The gateway receives the encrypted value and uses its own private key to decrypt it. Now both have new shared key.
WEP
Wired Equivalent Privacy
Weakness of WEP
Uses Initialization Vector (IV) and shared key between users.
-Many sites use same shared key for all users, thus any individual can listen to anybody’s communication – sort of like ethernet.
War Chalking
Marking open wifi spots
Broadband vs. Baseband
- Baseband uses a signal pulsed directly on the transmission medium in the form of high-speed, square-wave pulses of direct current voltage.
- Broadband systems use cable television technology to divide the transmission medium into frequency bands or channels. Each broadband channel can be multiplexed to carry data, voice, or video.
ISDN
Integrated Services Digital Network
ISDN Goals
Provide an international standard for voice, data and signaling
Make all transmission circuits end-to-end digital
Adopt a standard out-of-band signaling system
Bring more bandwidth to the desktop
Purpose of ISDN
allows you to use your line for voice calls as well as data
BRI
Basic Rate Interface (Common ISDN configuration)
PRI
Primary Rate Interface (Common ISDN configuration)
DSL
Digital Subscriber Line
Variations of DSL
Asymmetric Digital Subscriber Line (ADSL)
Very high-speed DSL (VDSL)
G-Lite or Universal DSL
Rate adaptive DSL (RADSL)
VDSL
Very high-speed DSL.
Speeds as high as 10-26 Mbps downstream but need to be within 4500 feet of a phone switch.
ADSL
Asymmetric Digital Subscriber Line.
Speeds up to 8 Mbps downstream need to be 18,000 feet from phone switch.
G-Lite
DSL. Allows only 1.5Mbps downstream at distances to 18,000 feet from the phone switch.
RADSL
Rate adaptive DSL.
Reaches as far as 21,000 feet but is limited to 600Kbps-7Mbps downstream.
LMDS
Local Multipoint Distribution System (Wireless)
-Receiver dishes located on top of apartment buildings can receive signal to broadcast to apartments via coax.
-Can also utilize 18” antenna in subscriber’s home
-Variations used to transmit data and some attempts with voice.
-Local Multipoint Communication System (LMCS) used in Canada for wireless broadband data signals
Rates up to 155 Mbps
SSID
Service Set Identifier
