1. 1 Chapter Overview Wireless Technologies Wireless Security

2. Wireless communication Wireless communication is the transfer of information over a distance without wire Short distance – TV remote Long distance – radio Wireless communication can be via: radio frequency communication, microwave communication, for example long-range line-of-sight via highly directional antennas, or short-range communication, or infrared (IR) short-range communication, for example from remote controls or via Infrared Data Association (IrDA). Applications may involve point-to-point communication, point-to-multipoint communication, broadcasting, cellular networks and other wireless networks. 2

3. Wireless networking Use various types of unlicensed 2.4 and 5 GHz WiFi (Wireless Fidelity) devices Is used to connect computers (mostly laptops) users Another common use is for mobile networks that connect via satellite. We use wireless network: To span a distance beyond the capabilities of typical cabling to overcome situations where wiring is difficult or financially impractical, To link portable or temporary workstations, To remotely connect mobile users or networks. Generally, we refer them as IEEE 802.11 3

4. Basic operation model Half-duplex Broadcast Using 2.4 and 5 GHz radio frequencies These are FCC released for public use The 900MHz and 2.4 GHz are referred as ISM (Industrial, Scientific, and Medical) The reason you cannot use cell phone in hospitals The 5 GHz is knowns as (UNII) Unlicensed National Information Infrastructure 4

5. Where is 2.4 GHz 5

6. 802.11 network standards (Wiki) 802.1 Release Freq.Bandwidth Data rate per stream Allowabl e Modulation Apx. indoor range Apx. Outdoor range Protoco l (GHz)(MHz)(Mbit/s) MIMO streams (m)(ft)(m)(ft) –Jun-972.4201, 21DSSS2066100330 aSep-99 5 20 6, 9, 12, 18, 24, 36, 48, 541OFDM 35115120390 3.7-- 5,00016,000 bSep-992.4201, 2, 5.5, 111DSSS38125140460 gJun-032.420 1, 2, 6, 9, 12, 18, 24, 36, 48, 541OFDM, DSSS38125140460 nOct-092.4/5 20 7.2, 14.4, 21.7, 28.9, 43.3, 57.8, 65, 72.2 4OFDM 70230250820 40 15, 30, 45, 60, 90, 120, 135, 15070230250820 6

7. In door range 7

8. Channels 8

9. Benefits of 802.11n Up to 250 Mbps 40 Mhz channels Waste less “real estate” MAC Efficiency Less protocol communication overhead Multiple-Input Multiple-Output (MIMO) support (pronounced my-moh or me-moh) Need support of both NIC and AP Great for home video $$$, with little business values 9

10. MIMO 10

11. Wireless Network Components Wireless Access Points Can be very different for an enterprise vs. home usage Always has a port to connect to wired network Wireless Network Interface Card Many types Build in PCI USB 11

12. Antennas Omni directional Directional (Yagi) Point to point Longer range 12

13. Installing a wireless network Add an access point (AP) Configure it with its IP address 192.168.1.2 and a browser or software cames with it At least add a name for your network You can select not to broadcast the network name, but it must have a name (also called Service Set ID, SSID) May consider not to set the security initially Make sure the wired ports work NIC part Turn on the Wi-Fi button and let your computer search for a Wi-Fi network Move it up the list of networks if necessary 13

14. Infrastructure Mode: Basic Service Set (BSS) 14

15. Security Open access out of the box Basic security Service Set ID – need to know the network to access The device name Does not have to broadcast SSID is sent clear text in client messages (required ) Shared key authentication Wired Equivalent Privacy (WEP) A key entered at the NIC config AP sends client a message and asks the client to encrypt with the key and authenticated only if it can do that It is possible to decipher the key with the clear text and the respond Or just “replay” if the same message is sent for authentication 15

16. Security (2) Wired Equivalent Privacy (WEP) A key entered at the NIC config and AP config Key must match in order to communicate with the AP Save enough for home network, not suitable for large networks May have multiple so you can issue a few temporary ones Still has holes MAC address authentication The MAC address of NICs are entered to communicate 16

17. Security (3) RADIUS (Remote Authentication Dial In User Service) Authentication, Authorization, centralized access, and accounting supervision User ID and password in clear text on the RADIUS server 17

18. Security (4) TKIP (Temporal Key Integrity Protocol) Build on top of WEP Use up to 128-bit encryption Each package has it own key = Basic Key + Mac Address + 48-bit packet serial number Cannot replay Can still be attacked (differ from our book) Wi-Fi Protected Access (WPA and WPA2) Use an encryption mode with mathematically proven security when select AES as the encryption method 18

19. WPA/WPA2 19

20. Locking things down Once you have tested the AP and NIC with open access – no security, locking everything down with WPA 20

21. Wireless for enterprise Very different game APs need to have 10% overlap in terms of coverage areas Security considerations Keys MAC Accounting 21

22. The ad hoc mode Computer and computer can communicate without access points Generally not recommended Need to change setting at the NIC configuration level 22

23. ? Will wireless networks replace wired networks 23