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Wireless Fidelity ( Wi-Fi )

Wireless Fidelity ( Wi-Fi ). Submitted by, Premsingh Thangasamy.S 9911112007 I year M.Tech Network Engineering. Agenda. Introduction How Wi-Fi Works? Wi-Fi Technology How to connect Wi-Fi Network? Wi-Fi Access Protocol

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Wireless Fidelity ( Wi-Fi )

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  1. Wireless Fidelity(Wi-Fi) Submitted by, Premsingh Thangasamy.S 9911112007 I year M.Tech Network Engineering

  2. Agenda • Introduction • How Wi-Fi Works? • Wi-Fi Technology • How to connect Wi-Fi Network? • Wi-Fi Access Protocol • Wi-Fi Applications • Issues in Wi-Fi networks • Wi-Fi Security • Advantages • Limitations

  3. Wireless Technology is an alternative to Wired Technology, which is commonly used, for connecting devices in wireless mode. • A Wi-Fi is an electronic devices, such as a personal computer, video game console, Smartphone, or digital audio player can connect to the internet via a wireless network access point. • An access point (or hotspot) has a range of about 20 meters (65 feet) indoors as few rooms and a greater range outdoors, as many square miles. • Wi-Fi access can provide at Organizations and businesses such as homes, offices, airports, hotels and restaurants often provide free-use hotspots to attract or assist clients. Introduction

  4. How Wi-Fi works? • There are three most important items which makes Wi-Fi working in your laptop or desktop. These are, • Radio Signals • Wi-Fi Card which fits in your laptop or computer. • Hotspots which create Wi-Fi Network.

  5. Wi-Fi Technology • Wi-Fi (Wireless Fidelity) is a generic term that refers to the IEEE 802.11 communications standard for Wireless Local Area Networks (WLANs). • IEEE 802.11 wireless LANs provides 1- or 2-Mbps transmission in the 2.4-GHz band using either frequency-hopping spread spectrum (FHSS) or direct-sequence spread spectrum (DSSS). • The 802.11 standard is defined through several specifications of WLANs such as, • IEEE 802.11b • IEEE 802.11a • IEEE 802.11g

  6. 802.11 standards

  7. How to connect 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.

  8. Wi-Fi Access Protocol • MAC Protocols: • The 802.11 standards use a MAC layer known as CSMA/CA (Carrier Sense Multiple Access/Collision Avoidance). In CSMA/CA a Wireless node that wants to transmit & performs the following sequence: • Listen on the desired channel. • If channel is idle (no active transmitters) it sends a packet. • If channel is busy then, the node waits until the transmission end then a contention period where minimum time a host must transmit before it can be sure that the no other host’s packet has collided with its transmission. • If the channel is still idle at the end of the contention period, then the node transmits its packet otherwise it repeats the process defined in step-3 above until it gets a free channel.

  9. Wi-Fi Applications • As Wi-Fi enabled devices have become more and more popular, wired devices are quickly becoming a thing of the past. Check out some of the new ways that Wi-Fi is being used below. • Home or office. • Large Corporations & Campuses • Small Businesses or SOHO.

  10. Whole house connectivity

  11. Public place connectivity

  12. Issues in Wi-Fi networks • Wireless technology doesn’t remove any old security issues, but introduces new ones. • Hidden Terminal Problem • Exposed Terminal Problem • MITM Attack(Man-in-the-middle attacks)

  13. Hidden Terminal Problem • The hidden node/ terminal problem found at a point to multipoint network and it is defined as being one in which three or more nodes are present. Let there are three nodes: node A, node B and node C. • A and C cannot hear each other. • A sends to B, C cannot receive A. • C wants to send B, C senses a free medium. • Collision occurs at B. • A cannot receive the collision. • A is hidden for C.

  14. Exposed Terminal Problem • Suppose there are four nodes: node A, node B, node C and node D.Here, • B can send to both A and C. • C can send to D, but not to A or B. • A and C cannot hear each other. • Now the Problem as follows - • When B transmits to A, C detects the transmission using the carrier sense mechanism. • So C defers transmitting to D. • But C could have sent to D, so blocked unnecessarily.

  15. 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

  16. Wi-Fi Security Techniques • There are following security mechanisms in Wi-Fi networks.such as, • Wired Equivalent Privacy (WEP) • Wireless Protected Access (WPA)

  17. Wired Equivalent Privacy (WEP) • Provide same level of security as by wired network. • Uses RC4 based 40-or 104-bit encryption with pre-shared keys(static key) and 24 bit initialization vectors (IV). • Encrypt data only between 802.11 stations.once it enters the wired side of the network (between access point) WEP is no longer valid. • Security Issue with WEP • Short IV • Static key • Offers very little security at all.

  18. Wireless Protected Access (WPA) • This is a new standard from the Wi-Fi Alliance that uses the 40 or 104-bit WEP key, but it changes the key on each packet. • That changing key functionality is called the Temporal Key Integrity Protocol (TKIP). • Uses RC4,dynamic encryption with sessionkeys and 48 bit initialization vectors (IV). • Encryption provide Protection against man-in-the-middle attacks.

  19. Advantages • Mobility • Ease of Installation • Flexibility • Cost • Reliability • Security • Use unlicensed part of the radio spectrum • Roaming • Speed

  20. Limitations • Compatibility and Interpretability  • Billing Issues • Interference • Mobility • High power consumption • Limited range • Data security risks

  21. Conclusion • Wi-Fi is a universal wireless networking technology that utilizes radio frequencies to transfer data. • Wi-Fi allows for high speed Internet connections without the use of cables or wires. • It allows you to connect to the Internet from just about anywhere a coffee shop, a bed in a hotel room or a conference room at work without wires. • And the best thing of all, it's super fast almost 10 times faster than a regular dial-up connection.

  22. What is Next? • Now the focus in wireless is shifting to the wide area. • Wi-Max, short for Worldwide Interoperability for Microwave Access, is defined in IEEE 802.16 standards is designed to deliver a metro area broadband wireless access (BWA) service. • Wi-MAX is similar wireless system to Wi-Fi, but on a much larger scale and at faster speeds.

  23. Thank you

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