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Wi-Fi Technology• Guided by: Jenela Prajapati
• Presented by:(08bec039)
Nikhlesh khatra
• Introduction• Wi-Fi Technologies• Wi-Fi Protocols• Wi-Fi Channel• Wi-Fi Network Elements• How a Wi-Fi Network Works• Wi-Fi Network Topologies• Wi-Fi Security Threats• Wi-Fi Security Techniques• Advantages/ Disadvantages of Wi-Fi
Topics to be covered
• Wi-Fi(Wireless Fidelity) is a generic term that refers to the IEEE 802.11 communications standard for Wireless Local Area Networks (WLANs).
• Wi-Fi is the wireless way to handle networking.
• Wi-Fi Network can connect computers to each other, to the internet and to the wired network.
Introduction
• Wi-Fi Networks use Radio Technologies to transmit & receive data at high speed:
• Wi-Fi protocols: There are several new extensions have
been added to the core 802.11 protocols.
• IEEE 802.11b• IEEE 802.11a• IEEE 802.11g
The Wi-Fi Technology
• Appear in late 1999• Operates at 2.4GHz radio spectrum• 11 Mbps (theoretical speed) - within 30 m
Range• 4-6 Mbps (actual speed)• 100 -150 feet range• Most popular, Least Expensive• Interference from mobile phones and
Bluetooth devices which can reduce the transmission speed.
IEEE 802.11b
• Introduced in 2001• Operates at 5 GHz (less popular) • 54 Mbps (theoretical speed)• 15-20 Mbps (Actual speed)• 50-75 feet range• More expensive• Not compatible with 802.11b
IEEE 802.11a
• Introduced in 2003• Combine the feature of both standards (a,b)• 100-150 feet range• 54 Mbps Speed• 2.4 GHz radio frequencies• Compatible with ‘b’
IEEE 802.11g
802.11 802.11a 802.11b 802.11gFrequency 2.4 GHz 5 GHZ 2.4 GHZ 2.4 GHz
Data Rate 1,2 Mbps
5,9,12,18,24,36,48,54 Mbps
1,2,5.5,11 Mbps
6,9,12,15,24,36,48,54 Mbps
Modulation FHSS, DSSS
OFDM DSSS OFDM
Comparison
• Direct Sequence Spread Spectrum (DSSS)• Frequency Hoping Spread Spectrum
(FHSS)• Orthogonal Frequency Division
Multiplexing(OFDM)
CHANNELS
• Direct sequence signaling technique divides the 2.4 GHz band into 11 22-MHz channels. Adjacent channels overlap one another partially, with three of the 11 being completely non-overlapping. Data is sent across one of these 22 MHz channels without hopping to other channels.
DSSS Channels
• Each of three UNII bands(lower ,upper & middle) provides 4 chennels for communication in 802.11a network.
• Chennels are separated with no overlapping.
• Each channel is 20MHz wide surrounding the center frequency.
OFDM Channels
• FHSS system hop from frequency to frequency using a pseudorandom hopping sequence.
• This hopping sequence or pattern is defined as the channel.
FHSS
THREE IMPORTANT CONCEPTS• Data Rate• Actual Throughput• Dynamic Rate Selection
• Access Point (AP) - The AP is a wireless LAN transceiver or “base station” that can connect one or many wireless devices simultaneously to the Internet.
• Wi-Fi cards - They accept the wireless signal and relay information.They can be internal and external.(e.g PCMCIA Card for Laptop and PCI Card for Desktop PC)
• Safeguards - Firewalls and anti-virus software protect networks from uninvited users and keep information secure.
Elements of a WI-FI Network
• Basic concept is same as Walkie talkies.• A Wi-Fi hotspot is created by installing an access
point to an internet connection.• An access point acts as a base station. • When Wi-Fi enabled device encounters a hotspot the
device can then connect to that network wirelessly.• A single access point can support up to 30 users and
can function within a range of 100 – 150 feet indoors and up to 300 feet outdoors.
• Many access points can be connected to each other via Ethernet cables to create a single large network.
How a Wi-Fi Network Works
• Wireless network can function in one of two basic modes:
1) Ad-hoc2) Infrastructure
Operational modes
• Wireless technology doesn’t remove any old security issues, but introduces new ones• Eavesdropping• Man-in-the-middle attacks• Denial of Service
Wi-Fi Security Threats
• Easy to perform, almost impossible to detect
• By default, everything is transmitted in clear text• Usernames, passwords, content ...• No security offered by the transmission medium
• Different tools available on the internet• Network sniffers, protocol analysers . . .• Password collectors
• With the right equipment, it’s possible to eavesdrop traffic from few kilometers away.
Eavesdropping
1. Attacker spoofes a disassociate message from the victim
2. The victim starts to look for a new access point, and the attacker advertises his own AP on a different channel, using the real AP’s MAC address
3. The attacker connects to the real AP using victim’s MAC address
MITM Attack
• Attack on transmission frequecy used• Frequency jamming• Not very technical, but works
• Attack on MAC layer• Spoofed deauthentication / disassociation messages• can target one specific user
Denial of Service
The requirements for Wi-Fi network security can be broken down into two primary components:
• Authentication User Authentication Server Authentication
• Privacy
Wi-Fi Security
• Service Set Identifier Hiding(SSID)
• Wired Equivalent Privacy (WEP)
• 802.1X Access Control
• Wireless Protected Access (WPA)
• IEEE 802.11i
Wi-Fi Security Techniques
• Mobility• Easy Installation• Flexibility• Cost• Reliability• Use unlicensed part of the radio spectrum• Speed
Advantages
• Interference• High power consumption• Limited range• Security
Limitations