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