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Wi-FiPresented By-

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Wifi What it standsfor?

Wi-fi suggests Wireless-Fidelity, compared with the long

established audio recording term High Fidelity or Hi-Fi.Wi-Fi is simply a trademarked term meaning IEEE 802.11x.

.

.

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When Wi-Fi

Originated ? The precursor to wi-fi was invented in

1991 by NCR Corporation in Nieuwegein,

the Netherland. The first wireless products were brought

on the market under the name WaveLAN

with speeds of 1 Mbit/s to 2 Mbit/s.

Vic Hayes has been named as father of

Wi-Fi.

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The Architecture

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How Wi-Fi Works?

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Wi-Fi Standards

Standard Speed Freq band Notes

802.11 2 Mbps 2.4 GHz (1997)

802.11a 54 Mbps 5 GHz (1999)802.11b 11 Mbps 2.4 GHz

802.11g 54 Mbps 2.4 GHz

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StandardsIEEE 802.11.b 2.4GHz 11Mbps

Introduction to Wireless /802.11b

International standard for wireless networking that

operates in the 2.4 GHz frequency range (2.4 GHz to2.4835 GHz) and provides a throughput of up to 11 Mbps

with a range of just over 300 feet indoors. This is a very

commonly used frequency. Microwave ovens, cordless

phones, medical and scientific equipment, as well as

Bluetooth devices, all work within the 2.4 GHz frequencyband.

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StandardsIEEE 802.11.b 2.4GHz 11Mbps


802.11b enables transfers of up to 11 Mbps.

Comparable to 10BaseT in speeds, 802.11b is the mostcommon wireless standard deployed today. In

comparison T1 speeds are 1.54Mbps and DSL is

normally in the 640Kbps range.

Most deployments of Wireless utilize 802.11b

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StandardsIEEE 802.11.a 5GHz 11Mbps


International standard for wireless networking that

operates in the 5 GHz frequency range (5.725 GHz to

5.850 GHz) with a maximum 54 Mbps data transferrate. The 5 GHz frequency band is not as crowded as

the 2.4 GHz frequency, because the 802.11a

specification offers more radio channels than the

802.11b. These additional channels can help avoidradio and microwave interference.

Cost of 802.11a equipment is approximately twice thatof 802.11b and current deployment is limited.

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Standards IEEE 802.11.b 2.4GHz 11Mbps IEEE 802.11.a 5GHz 54 Mbps

IEEE 802.11g 2.4Ghz Hybrid11/54Mbps

802.11g is in the final stages ofdevelopment. The current draft (V5.0) is

open for comments until January 8, 2003.


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802.11a (Contd)

54 Mbps

48 Mbps36 Mbps

24 Mbps

12 Mbps2 Mbps

5.5 Mbps

11 Mbps

802.11a 802.11b

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..

What a wireless network is made up of:

Wireless Network cards

-Radios which send and receive signals from other radios or

access points, usually PCMCIA* cards which fit into Laptop

expansion slots, or PCI Bus in case of Desktop computers.

(There are other, simpler options using USB).PDAs like Blackberry, and Pocket PC having a compact flash

slot can also connect.

*PCMCIA Personal Computer Memory Card International Association.

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..

What a wireless network is made up of:

Base stations, Access points, or

Gateways-The base station sends and receives radio signals to and

from the Wi-Fi radio in your laptop or PC, enabling you to

share your Internet connection with other users on the

network. Access points and gateways have a wide range offeatures and performance capabilities, but they all provide

this basic network

connection service.

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WLAN ArchitectureAd Hoc Mode Ad-Hoc mode: Peer-to-peer setup where

clients can connect to each other directly.

Generally not used for business networks.

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WLAN Architecture--Mesh

Mesh: Every client in

the network also acts

as an access or relay

point, creating a self-healing and (in

theory) infinitely

extensible network.

Not yet in widespread

use, unlikely to be in

homes.

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WLAN ArchitectureInfrastructure Mode

To Wired Network

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Propagation Characteristics

900MHz

Multipath: High

Foliage: Pine (Absorb Radiation)

2.4GHzMultipath: Very High (Concrete, Brick, Steel)

Foliage: Any Absorbs Radiation (water resonance)

5GHz

Multipath: Very High (Concrete, Brick, Steel, Foliage)

Foliage: Limited Absorption

As you increase the frequency, the coverage areadecreases but potential data rates increase.

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Elements of a WI-FI Network Access Point (AP) - The AP is a wireless LAN

transceiver or base station that can connect one ormany

wireless devices simultaneously to the Internet.

Wi-Fi cards - They accept the wireless signal and relayinformation.They can be internal and external.(e.g PCMCIA

Card for Laptop and PCI Card for Desktop PC)

Safeguards - Firewalls and anti-virus software protectnetworks from uninvited users and keep information secure.

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How a Wi-Fi Network Works 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 andup to 300 feet outdoors.

Many access points can be connected to each other via

Ethernet cables to create a single large network.

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Wi-Fi Configurations

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Wi-Fi SecurityThe requirements for Wi-Fi network

security can be broken down into two

primary components:

Authentication

User Authentication

Server Authentication

Privacy

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WiFi 24

Security techniques

WEP( wired equivalent privacy) 64/128 bits

Using RC4 algorithm, almost permanent key, very week

security, able to crack by collecting statistic

Current security level for 99.9% products on the market.

TKIP (temporal key integrity protocol )Used RC4 algorithm with with a 128-bit "temporal key"

but changes temporal keys every 10,000 packets and key dependes

on address and sequence number.

Will be required to obtain WiFi certification from 09/01/03

AE

S (Advanced Encryption Standard )New, much more stronger encryption, protect against hacker frames in

insertion. Need hardware accelerator. Optional feature.

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Security (Encryption, Content Filtering, Privacy, etc.)

Partition The Network

A safe practice is to create two separate

networks. A private network for day to daybusiness and a network for public access.

Both can be wireless. These networks can

talk to one another through a proxy server

that will protect the private network frommalicious attacks via the public network.

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Encryption

Encryption on the pubic network can be usedbut would create administrative overhead.

Encryption keys would have to be changedregularly and anyone using their own laptopwould have to be given the key.

Encryption works best in a network that does

not allow people to use their own laptops. Encryption increases privacy, but can be

thwarted, either by software, or by gainingaccess to a PC configured with wireless andwriting down the key.

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Content Filtering & Proxy ServersWeb content filtering that has generally been

software on the desktop would have to be handled

by a server if people are allowed to use their ownlaptops.

Proxy servers allow you to control what informationpeople have access to. This is a good practice

anyway, allowing you to control at a global levelwhat information travels over your network. It alsoallows you to track usage.

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Viruses and Hacker

Wireless does not add any additional threat

in the way of viruses.

Anyone, anywhere can attack a network

that is connected to the Internet. Wireless

does not increase that chance. Security

measures such as firewalls, can reduce therisk.

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Wi-Fi Security Threats Wireless technology doesnt remove any

old security issues, but introduces new

ones

Eavesdropping

Man-in-the-middle attacks

Denial of Service

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Eavesdropping 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 . . .

P

assword collectors With the right equipment, its possible to

eavesdrop traffic from few kilometers away

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MITM Attack1. Attacker spoofes a

disassociate messagefrom the victim

2. The victim starts to look

for a new access point,and the attackeradvertises his own APon a different channel,using the real APs MAC

address3. The attacker connects

to the real AP usingvictims MAC address

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Denial of Service 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

Attacks on higher layer protocol (TCP/IP protocol)

SYN Flooding

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Authentication Keeping unauthorized users off the network

User Authentication

Authentication Server is used

Username and password

Risk:

Data (username & password) send before secure channel

established

Prone to passive eavesdropping by attacker Solution

Establishing a encrypted channel before sending username

and password

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Authentication (cont..) Server Authentication

Digital Certificate is used

Validation of digital certificate occurs

automatically within client software

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..

Typical Community Wifi ConstituentsHigh gain Parabolic grid antennas

to beam the signal to over 30kmfrom tower to tower..

Customer Premises equipment

(CPE) to access the signal from thetowers..

Sector antennas to beam the signal

from the towers to the communityusers

Other components that need to be

installed in order to put the above

systems together

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Environment Assessment

Look at the structure of your building.

Steel, Concrete, Stone, Glass

Open w/ few walls or many separaterooms?

Current technologies used

Do you use a 2.4 GHz cordless phone?Does it work throughout your environment?

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Advantages Mobility

Ease of Installation

Flexibility

Cost Reliability

Security

Use unlicensed part of the radio spectrum

Roaming

Speed

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Advantages of Wi-Fi over other means

Wi-fi can make access publicly available at

wi-fi hotspots.

Does not require regulatory approval forindividual.

Wi-fi network can support roaming.

Wi-fi allows local area network to deployedwithout wires for client devices.

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Limitations Interference

Degradation in performance

High power consumption Limited range

Documents

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