gaurav bhatt 6167 wireless
Post on 30-May-2018
220 Views
Preview:
TRANSCRIPT
-
8/9/2019 Gaurav Bhatt 6167 Wireless
1/20
Made by Gaurav Bhatt
ECE 8th
Semester
-
8/9/2019 Gaurav Bhatt 6167 Wireless
2/20
Contents in the slide
Definition of wireless LAN
Its history
Architecture of WLAN Common topology
Security features
-
8/9/2019 Gaurav Bhatt 6167 Wireless
3/20
What is a Wireless Lan
n/w
Wireless LAN is atype of local area
network thatuseshigh
frequency radiorather than
wires to
communicatebetween nodes.
-
8/9/2019 Gaurav Bhatt 6167 Wireless
4/20
History of wireless LAN
The first radio network technology was developed atUniversity of Hawaii in a research project callALOHANET. The ALOHANET system allows computerwith 7 sites, which spread out in four islands withoutusing any wired transmission links.
four islands
-
8/9/2019 Gaurav Bhatt 6167 Wireless
5/20
History of wireless LAN
In 1980 the hobbyists in Canada and US haddeveloped the equipment call TNCs (terminal nodecontroller).
-
8/9/2019 Gaurav Bhatt 6167 Wireless
6/20
Common TopologiesThe wireless LAN connects to a wired LAN
The access point bridges wireless LAN traffic into the wired LAN. The
access point (AP) can also act as a repeater for wireless nodes,effectively doubling the maximum possible distance between nodes.
-
8/9/2019 Gaurav Bhatt 6167 Wireless
7/20
System Architecture
Two basic systemarchitectures
1. Ad hoc
2. Infrastructure based
-
8/9/2019 Gaurav Bhatt 6167 Wireless
8/20
Ad hoc wireless LANs
A group of stations using the sameradio frequency Basic Service Set
The physical size of the network isdetermined by the maximum reliablepropagation range of the radio signals.Referred to as ad hoc networks
http://www.rococosoft.com/products/images/image_1.gif -
8/9/2019 Gaurav Bhatt 6167 Wireless
9/20
-
8/9/2019 Gaurav Bhatt 6167 Wireless
10/20
Infrastructure based
Wireless LANs Stations and Access
Points
Distribution systemconnects cells viaaccess points to forma single network
Extends wireless areacoverage
-
8/9/2019 Gaurav Bhatt 6167 Wireless
11/20
-
8/9/2019 Gaurav Bhatt 6167 Wireless
12/20
802.11 Wireless LAN
Provides network connectivity over wireless
media
An Access Point (AP) is installed to act asBridge between Wireless and WiredNetwork
The AP is connected to wired network and
Network
connectivity
to the
legacywired LAN
Desktop
with PCI 802.11 LAN card
Laptop
with PCMCIA 802.11 LAN cardAccess Point
-
8/9/2019 Gaurav Bhatt 6167 Wireless
13/20
Access Points
Stations select an AP and associate with it Support roaming
Provide other functions time synchronization
power management support
point coordination function
Traffic typically (but not always) flows
through AP direct communication possible
-
8/9/2019 Gaurav Bhatt 6167 Wireless
14/20
802.11b Security Features
Wired Equivalent Privacy (WEP) A protocol toprotect link-level data during wirelesstransmission between clients and accesspoints.
Services: Authentication: provides access control to the
network by denying access to client stations that failto authenticate properly.
Confidentiality: intends to prevent informationcompromise from casual eavesdropping
Integrity: prevents messages from being modifiedwhile in transit between the wireless client and the
access point.
-
8/9/2019 Gaurav Bhatt 6167 Wireless
15/20
Authentication
Means: Based on cryptography
Non-cryptographic
Both are identity-based verificationmechanisms (SSID Service Set Identifier ofthe wireless network).
-
8/9/2019 Gaurav Bhatt 6167 Wireless
16/20
Privacy
Cryptographic techniques
WEP Uses RC4 symmetric key, streamcipher algorithm. The stream is XORed with
the data to be transmitted
Key sizes: 40 bits to 128 bits
-
8/9/2019 Gaurav Bhatt 6167 Wireless
17/20
Data Integrity
Data integrity is ensured by a simpleencrypted version of CRC (Cyclic RedundantCheck)
Also vulnerable to some attacks
-
8/9/2019 Gaurav Bhatt 6167 Wireless
18/20
Security Problems
Use of static WEP keys (keys are in use for avery long time).
WEP does not provide key management.
Cryptographic keys are short.
No user authentication occurs only devicesare authenticated. A stolen device can accessthe network.
Identity based systems are vulnerable.
Packet integrity is poor.
-
8/9/2019 Gaurav Bhatt 6167 Wireless
19/20
-
8/9/2019 Gaurav Bhatt 6167 Wireless
20/20
top related