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wi-fi technology

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  3. 3. <ul><li>The IEEE 802.11 technology standards, better known as Wi-Fi technology. </li></ul><ul><li>It is being deployed into Broadband Wireless Access (BWA) equipment and Local Area Network (LAN) access points. </li></ul><ul><li>It quickly and efficiently connect computers to internet service providers and to LAN’s respectively. </li></ul>
  4. 4. <ul><li>Wireless communication has a few problems such as data rate, distance and reliability. </li></ul><ul><li>The congested air waves and lack of Federal Communication Commission (FCC) regulations on transmission etiquette lead to the one major downfall of wireless communications. </li></ul><ul><li>It uses two transmitting schemes Frequency Hopping Spread Spectrum (FHSS) or Direct Sequence Spread Spectrum (DSSS). </li></ul><ul><li>. </li></ul>
  5. 5. FHSS <ul><li>“ The FHSS carrier will hop on predetermined,pseudo random pattern defined using a pool of 1 MHz sub-channels defined across the entire band. </li></ul><ul><li>The FCC requires the band to be divided into at least 75 sub-channels </li></ul><ul><li>The hopping ability creates additional security for FHSS. It is very difficult for any unauthorized retrieval of the data. </li></ul><ul><li>FHSS stays on a certain band in the frequency for a maximum of 400 microseconds </li></ul>
  6. 6. DSSS <ul><li>Direct sequence spread spectrum is the second type of spread spectrum signal transmission allowed for BWA equipment by the FCC </li></ul><ul><li>Direct sequence spread spectrum transmitters use power levels for transmission that are similar to narrow band transmitters. </li></ul><ul><li>The DSSS signal has a redundancy factor </li></ul><ul><li>built into the equipment.It actually transmits at least 10 fully redundant copies of the data. It helps to resist interference from other signals. </li></ul>
  7. 7. <ul><li>DSSS has a process called de-spreading that helps reduce or possibly eliminate interference </li></ul><ul><li>The Signal to Noise ratio is better for DSSS since the de-spreading helps reduce the amount of noise being received by the equipment. </li></ul><ul><li>The DSSS equipment has a considerable outdoor range of 40km or approximately 24.8 miles. </li></ul><ul><li>Also, the DSSS systems can send 1500 or 2400 bytes of data </li></ul>
  8. 8. <ul><li>The success of wireless technology is pressing technology companies to produce more wireless “gadgets” based on newer standards that fix some of Wi-Fi’s shortcomings </li></ul><ul><li>So that WiMax enters into the wireless industry. </li></ul>
  9. 9. WIMAX <ul><li>WiMax,which stands for Worldwide Interoperability for Microwave Access </li></ul><ul><li>“ WiMax is the popular name of the (IEEE’s) 802.16 wireless metropolitan-area network standard </li></ul><ul><li>WiMax can span distances of up to 31 miles, non line of sight </li></ul><ul><li>WiMax uses low frequencies, in the 2 to 11 GHz range. </li></ul>
  10. 10. <ul><li>Wi-Fi and WiMax technologies are being deployed by Internet Service Providers is to help minimize costs </li></ul><ul><li>The 802.16e standard that is being developed has been predicted to allow users to travel at speeds of up to 60 miles per hour and still maintain a steady reliable connection </li></ul><ul><li>This could decrease the number of future Wi-Fi “hot spots” and allow the WiMax 802.16e standard to replace them with WiMax </li></ul><ul><li>“ hot spots.” </li></ul><ul><li>WiMax promises to help corporations expand business, drive down costs, increase overall </li></ul><ul><li>profitability, increase the quality of service, and increase the number of users that connect to the </li></ul><ul><li>internet </li></ul>
  11. 11. REFERENCES <ul><li>1. Captain, S. (2004). WiMax: Wireless on Steroids. PC World, Vol. 22 Issue 1. [Online]. </li></ul><ul><li>Available: http://www.pcworld.com/reviews/article/0,aid,112467,00.asp. </li></ul><ul><li>2. Direct Sequence vs. Frequency Hopping (2000). [Online]. Available: </li></ul><ul><li>http://www.wavewireless.com/classroom/whitepapers/FHSSvDSSS.pdf </li></ul><ul><li>3. Fisher, K. (2004, January). WiMax Technology May Solve ‘Last Mile’ Problem for High- </li></ul><ul><li>Speed Access. [Online]. Available: </li></ul><ul><li>http://www.arstechnica.com/news/posts/1074799974.html </li></ul><ul><li>4. Reinhardt, A. (2004, January 19). The Next Big Thing for Wireless?. Business Week Online. </li></ul><ul><li>[Online]. Available: </li></ul><ul><li>http://www.businessweek.com/magazine/content/04_03/b3866083_mz063. </li></ul><ul><li>5. Russell, K. (2003). WiMax. Computerworld, 37(48). [Online]. Available: </li></ul><ul><li>http://www.computerworld.com/mobiletopics/mobile/story/0,10801,87555,00.html </li></ul><ul><li>6. Stone, B. (2003, November 17). VC Inside. Newsweek. [Online]. Available: </li></ul><ul><li>http://msnbc.msn.com/Default.aspx?id=3403581&p1=0 </li></ul><ul><li>7. The WiMax Forum: At-a- glance (n.d.). [Online]. Available: http://www.alvarionusa. </li></ul><ul><li>com/runtime/materials/pdffiles/WiMAX_Leaflet.pdf </li></ul>
  12. 12. Faults in Wifi <ul><li>There are several specific reasons why maintenance in rural areas is hard. </li></ul><ul><li>Limited knowledge about wireless networking. </li></ul><ul><li>The chances of hardware failures are higher as a result of poor power quality. </li></ul><ul><li>Many locations with wireless nodes, especially relays, are quite remote. </li></ul><ul><li>The wireless deployment, although connecting lo-cal nodes, may not be accessible remotely or through the Internet. </li></ul>
  13. 13. REQUIREMENTS FOR DIAGNOSIS <ul><li>Monitoring </li></ul><ul><li>It’s hard to log in to individual routers to collect monitoring data because the complete network </li></ul>Type # Description HW <ul><li>63 </li></ul><ul><li>7 </li></ul><ul><li>21 </li></ul><ul><li>3 </li></ul><ul><li>1 </li></ul><ul><li>1 </li></ul>Router board not powered on (grid outage, battery dead) Router powered but wedged (low voltage, corrupt CF cards) Router powered but not connected to re- mote LAN (loose ethernet cables, burnt ethernet ports) Router on, but wireless cards not transmit- ting due to low supplied voltage Router on, but pigtails not connected or other RF connectors gone bad Router on, but antenna misaligned SW 4 3 2 2 No default gateway specified Wrong ESSID, channel, mode Wrong IP address Misconfigured routing Driver errors, wireless cards not recognized
  14. 14. Need to monitor status <ul><li>Network status: The admins need an infrastructure that continuously probes all the nodes and relays (e.g. ping tests) </li></ul><ul><li>Signal strength: It is possible that the antenna is misaligned, or that some antenna cable or connector is disconnected. </li></ul><ul><li>It is possible that the antenna is misaligned, or that some antenna cable or connector is disconnected. </li></ul><ul><li>Local connectivity: One common problem with the </li></ul><ul><li>router boards is that the main ethernet port often stops working because of power spikes or lightening strikes on long exposed cables carrying power (PoE) </li></ul>
  15. 15. Need to have back channels <ul><li>Network misconfiguration: </li></ul><ul><li>A related problem occurs when there is a routing misconfiguration or loop. </li></ul><ul><li>A particular node may be reachable but the reverse path may not work; thus pings fail to return. </li></ul><ul><li>Arelated problem occurs when there is a routing misconfigu-ration or loop; a particular node may be reachable but the reverse path may not work; thus pings fail to return. </li></ul>
  16. 16. <ul><li>Independent channel: We need the ability to access the remote nodes independently from the primary wireless link </li></ul><ul><li>Need for separate hardware control: Hard reboots: A link might be down because the board might have reached a state where it needs to be rebooted </li></ul><ul><li>We need an independent hardware based module that reboots the system when it does not receive periodic heartbeats. </li></ul>
  17. 17. <ul><li>Need for independent software services </li></ul><ul><li>Software watchdog:We have seen problems where the routing daemon dies or goes into a bad state. </li></ul><ul><li>This might result in nodes becoming unreachable. </li></ul><ul><li>We need a safe fallback mechanism. In some cases we need the ability to set a timeout period for new configurations where we want to test it with the guarantee that the system would go back to a safe state after the specified timeout. </li></ul>
  18. 18. CONCLUSION Simplification of diagnosis for rural WiFi networks is an important step in empowering rural administrators, building local capacity, and improving the operational sustainability of the system. In this paper we have presented a framework for designing networks with support for more accurate root cause fault diagnosis. The key ideas are building redundancy into hardware, software, and links for diagnosis such that some subsystems remain available even in the event of pri-mary link failure and thus can still be queried. We show our progress to this end by describing our initial architecture and describing how faults can be diagnosed in this framework.
  19. 19. REFERENCES <ul><li>[1] Ashwini: Association for Health Welfare in the </li></ul><ul><li>Nilgiris. http://www.ashwini.org. </li></ul><ul><li>[2] Atheros. MadWiFi driver for Atheros Chipsets. </li></ul><ul><li>http://sourceforge.net/projects/madwifi/. </li></ul><ul><li>[3] K. Chebrolu, B. Raman, and S. Sen. Long-Distance </li></ul><ul><li>802.11b Links: Performance Measurements and </li></ul><ul><li>Experience. In ACM MOBICOM, 2006. </li></ul><ul><li>[4] CRCNet: Connecting Rural Communities Using WiFi. </li></ul><ul><li>http://www.crc.net.nz. </li></ul><ul><li>[5] M. Demmer, E. Brewer, K. Fall, S. Jain, M. Ho, and </li></ul><ul><li>R. Patra. Implementing Delay Tolerant Networking. </li></ul><ul><li>Intel Research Berkeley Technical Report </li></ul><ul><li>IRB-TR-04-020, 2004. </li></ul><ul><li>[6] Digital Gangetic Plains. </li></ul><ul><li>http://www.iitk.ac.in/mladgp/. </li></ul>
  20. 20. ATTACKS ON WI-FI NETWORKS <ul><ul><li>The framework to monitor various attacks called DAIR, </li></ul></ul><ul><ul><li>which is short for Dense Array of Inexpensive Radios </li></ul></ul><ul><ul><li>It is useful for detecting rogue wireless </li></ul></ul><ul><ul><li>devices (e.g., access points) attached to corporate networks, as well as for detecting Denial of Service attacks on Wi-Fi networks. </li></ul></ul>
  21. 21. Types of Attacks <ul><ul><li>Eavesdropping </li></ul></ul><ul><ul><li>Man-in-the-middle attacks </li></ul></ul><ul><ul><li>Denial of Service </li></ul></ul>
  22. 22. Eavesdropping <ul><li>Easy to perform, almost impossible to detect </li></ul><ul><li>By default, everything is transmitted in clear text </li></ul><ul><ul><li>Usernames, passwords, content ... </li></ul></ul><ul><ul><li>No security offered by the transmission medium </li></ul></ul><ul><li>Different tools available on the internet </li></ul><ul><ul><li>Network sniffers, protocol analysers . . . </li></ul></ul><ul><ul><li>Password collectors </li></ul></ul><ul><li>With the right equipment, it’s possible to eavesdrop traffic from few kilometers away </li></ul>
  23. 23. MITM Attack <ul><li>Attacker spoofes a disassociate message from the victim </li></ul><ul><li>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 </li></ul><ul><li>The attacker connects to the real AP using victim’s MAC address </li></ul>
  24. 24. Denial of Service <ul><li>Attack on transmission frequecy used </li></ul><ul><ul><li>Frequency jamming </li></ul></ul><ul><ul><li>Not very technical, but works </li></ul></ul><ul><li>Attack on MAC layer </li></ul><ul><ul><li>Spoofed deauthentication / disassociation messages </li></ul></ul><ul><ul><li>can target one specific user </li></ul></ul><ul><li>Attacks on higher layer protocol (TCP/IP protocol) </li></ul><ul><ul><li>SYN Flooding </li></ul></ul>
  25. 25. Wi-Fi Security <ul><li>The requirements for Wi-Fi network security can be broken down into two primary components: </li></ul><ul><li>Authentication </li></ul><ul><ul><li>User Authentication </li></ul></ul><ul><ul><li>Server Authentication </li></ul></ul><ul><li>Privacy </li></ul>
  26. 26. Authentication <ul><li>Keeping unauthorized users off the network </li></ul><ul><li>User Authentication </li></ul><ul><ul><li>Authentication Server is used </li></ul></ul><ul><ul><li>Username and password </li></ul></ul><ul><ul><li>Risk: </li></ul></ul><ul><ul><ul><li>Data (username & password) send before secure channel established </li></ul></ul></ul><ul><ul><ul><li>Prone to passive eavesdropping by attacker </li></ul></ul></ul><ul><ul><li>Solution </li></ul></ul><ul><ul><ul><li>Establishing a encrypted channel before sending username and password </li></ul></ul></ul>
  27. 27. Authentication (cont..) <ul><li>Server Authentication </li></ul><ul><ul><li>Digital Certificate is used </li></ul></ul><ul><ul><li>Validation of digital certificate occurs automatically within client software </li></ul></ul>
  28. 28. Wi-Fi Security Techniques <ul><ul><li>Service Set Identifier (SSID) </li></ul></ul><ul><ul><li>Wired Equivalent Privacy (WEP) </li></ul></ul><ul><ul><li>802.1X Access Control </li></ul></ul><ul><ul><li>Wireless Protected Access (WPA) </li></ul></ul><ul><ul><li>IEEE 802.11i </li></ul></ul>
  29. 29. Service Set Identifier (SSID) <ul><li>SSID is used to identify an 802.11 network </li></ul><ul><li>It can be pre-configured or advertised in beacon broadcast </li></ul><ul><li>It is transmitted in clear text </li></ul><ul><ul><li>Provide very little security </li></ul></ul>
  30. 30. Wired Equivalent Privacy (WEP) <ul><li>Provide same level of security as by wired network </li></ul><ul><li>Original security solution offered by the IEEE 802.11 standard </li></ul><ul><li>Uses RC4 encryption with pre-shared keys and 24 bit initialization vectors (IV) </li></ul><ul><li>key schedule is generated by concatenating the shared secret key with a random generated 24-bit IV </li></ul><ul><li>32 bit ICV (Integrity check value) </li></ul><ul><li>No. of bits in keyschedule is equal to sum of length of the plaintext and ICV </li></ul>
  31. 31. Wired Equivalent Privacy (WEP) (cont.) <ul><li>64 bit preshared key-WEP </li></ul><ul><li>128 bit preshared key-WEP2 </li></ul><ul><li>Encrypt data only between 802.11 stations.once it enters the wired side of the network (between access point) WEP is no longer valid </li></ul><ul><li>Security Issue with WEP </li></ul><ul><ul><li>Short IV </li></ul></ul><ul><ul><li>Static key </li></ul></ul><ul><li>Offers very little security at all </li></ul>
  32. 32. 802.1x Access Control <ul><li>Designed as a general purpose network access control mechanism </li></ul><ul><ul><li>Not Wi-Fi specific </li></ul></ul><ul><li>Authenticate each client connected to AP (for WLAN) or switch port (for Ethernet) </li></ul><ul><li>Authentication is done with the RADIUS server, which ”tells” the access point whether access to controlled ports should be allowed or not </li></ul><ul><ul><li>AP forces the user into an unauthorized state </li></ul></ul><ul><ul><li>user send an EAP start message </li></ul></ul><ul><ul><li>AP return an EAP message requesting the user’s identity </li></ul></ul><ul><ul><li>Identity send by user is then forwared to the authentication server by AP </li></ul></ul><ul><ul><li>Authentication server authenticate user and return an accept or reject message back to the AP </li></ul></ul><ul><ul><li>If accept message is return, the AP changes the client’s state to authorized and normal traffic flows </li></ul></ul>
  33. 33. 802.1x Access Control
  34. 34. Wireless Protected Access (WPA) <ul><li>WPA is a specification of standard based, interoperable security enhancements that strongly increase the level of data protection and access control for existing and future wireless LAN system. </li></ul><ul><li>User Authentication </li></ul><ul><ul><li>802.1x </li></ul></ul><ul><ul><li>EAP </li></ul></ul><ul><li>TKIP (Temporal Key Integrity Protocol) encryption </li></ul><ul><ul><li>RC4, dynamic encryption keys (session based) </li></ul></ul><ul><ul><ul><li>48 bit IV </li></ul></ul></ul><ul><ul><ul><li>per packet key mixing function </li></ul></ul></ul><ul><ul><li>Fixes all issues found from WEP </li></ul></ul><ul><li>Uses Message Integrity Code (MIC) Michael </li></ul><ul><ul><li>Ensures data integrity </li></ul></ul><ul><li>Old hardware should be upgradeable to WPA </li></ul>
  35. 35. Wireless Protected Access (WPA)(cont.) <ul><li>WPA comes in two flavors </li></ul><ul><ul><li>WPA-PSK </li></ul></ul><ul><ul><ul><li>use pre-shared key </li></ul></ul></ul><ul><ul><ul><li>For SOHO environments </li></ul></ul></ul><ul><ul><ul><li>Single master key used for all users </li></ul></ul></ul><ul><ul><li>WPA Enterprise </li></ul></ul><ul><ul><ul><li>For large organisation </li></ul></ul></ul><ul><ul><ul><li>Most secure method </li></ul></ul></ul><ul><ul><ul><li>Unique keys for each user </li></ul></ul></ul><ul><ul><ul><li>Separate username & password for each user </li></ul></ul></ul>
  36. 36. WPA and Security Threats <ul><ul><li>Data is encrypted </li></ul></ul><ul><ul><ul><li>Protection against eavesdropping and man-in-the-middle attacks </li></ul></ul></ul><ul><ul><li>Denial of Service </li></ul></ul><ul><ul><ul><li>Attack based on fake massages can not be used. </li></ul></ul></ul><ul><ul><ul><li>As a security precaution, if WPA equipment sees two packets with invalid MICs within a second, it disassociates all its clients, and stops all activity for a minute </li></ul></ul></ul><ul><ul><ul><li>Only two packets a minute enough to completely stop a wireless network </li></ul></ul></ul>
  37. 37. 802.11i <ul><li>Provides standard for WLAN security </li></ul><ul><li>Authentication </li></ul><ul><ul><li>802.1x </li></ul></ul><ul><li>Data encryption </li></ul><ul><ul><li>AES protocol is used </li></ul></ul><ul><li>Secure fast handoff-This allow roaming between APs without requiring client to fully reauthenticate to every AP. </li></ul><ul><li>Will require new hardware </li></ul>
  38. 38. Advantages <ul><li>Mobility </li></ul><ul><li>Ease of Installation </li></ul><ul><li>Flexibility </li></ul><ul><li>Cost </li></ul><ul><li>Reliability </li></ul><ul><li>Security </li></ul><ul><li>Use unlicensed part of the radio spectrum </li></ul><ul><li>Roaming </li></ul><ul><li>Speed </li></ul>