Wi-Fi Technology

1. Wi-Fi Technology • Guided by: Jenela Prajapati • Presented by: (08bec039) Nikhlesh khatra

2. Topics to be covered • 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

3. Introduction • 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.

5. The Wi-Fi Technology • 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

6. IEEE 802.11b • 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.

7. IEEE 802.11a • 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

8. IEEE 802.11g • 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’

9. Comparison

10. CHANNELS • Direct Sequence Spread Spectrum (DSSS) • Frequency Hoping Spread Spectrum (FHSS) • Orthogonal Frequency Division Multiplexing(OFDM)

11. DSSS 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.

13. OFDM 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.

14. FHSS • FHSS system hop from frequency to frequency using a pseudorandom hopping sequence. • This hopping sequence or pattern is defined as the channel.

15. THREE IMPORTANT CONCEPTS • Data Rate • Actual Throughput • Dynamic Rate Selection

16. Elements of a WI-FI Network • 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.

17. 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 and up to 300 feet outdoors. • Many access points can be connected to each other via Ethernet cables to create a single large network.

19. Operational modes • Wireless network can function in one of two basic modes: • Ad-hoc • Infrastructure

20. Wi-Fi Security Threats • Wireless technology doesn’t remove any old security issues, but introduces new ones • Eavesdropping • Man-in-the-middle attacks • Denial of Service

21. 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 . . . • Password collectors • With the right equipment, it’s possible to eavesdrop traffic from few kilometers away.

22. MITM Attack • Attacker spoofes a disassociate message from the victim • 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 • The attacker connects to the real AP using victim’s MAC address

23. 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

24. Wi-Fi Security The requirements for Wi-Fi network security can be broken down into two primary components: • Authentication • User Authentication • Server Authentication • Privacy

25. Wi-Fi Security Techniques • Service Set Identifier Hiding(SSID) • Wired Equivalent Privacy (WEP) • 802.1X Access Control • Wireless Protected Access (WPA) • IEEE 802.11i

26. Advantages • Mobility • Easy Installation • Flexibility • Cost • Reliability • Use unlicensed part of the radio spectrum • Speed

27. Limitations • Interference • High power consumption • Limited range • Security