Wireless Technologies

1. Wireless Technologies Networking for Home and Small Businesses – Chapter 7

2. Wireless Technologies • The use of electromagnetic waves to carry information. • We call them “radio waves” • Common wireless technologies • Infrared • Radio Frequency Electromagnetic Spectrum

3. Infrared Technology • Line of sight transmission • Unable to penetrate through walls • IRDA port (Infrared Direct Access) • used to exchange information between devices • Used by: • remote controls • wireless mouse and keyboard

4. Radio Frequency (RF) Technology • Signal able to transmit through walls • RF bands set aside for wireless devices, including cordless phones and computer peripherals • 900 MHz – used by cell phones • 2.4 GHz • Bluetooth technology • low speed, short range • can communicate with many devices at once • 5 GHz • Wireless LAN • transmit at a higher level = greater distance • conform to 802.11 standards

5. Benefits of Wireless • Mobility • Scalability • can be added to a network easily • use of “hotspots” • Flexibility • anytime, anywhere connectivity • Cost • inexpensive to install • reduced installation costs

6. Limitations/Risks of Wireless • Uses unlicensed regions of the RF spectrum • used by many different devices • Interference • cordless phones • microwaves • Security • easy access to the network • encryption/authentication helps with security issues

7. Wireless Technologies • WPAN • Wireless Personal Area Network • used for: • mice • keyboards • PDAs

8. Wireless Technologies • WLAN • Wireless LAN • uses RF standards • conform to 802.11 standards • connects through Wireless AP

9. Wireless Technologies • WWAN • Wireless WAN • coverage over large areas • cell phone network

10. IEEE Wireless Standards • Define how wireless devices communicate • 802.11 – wireless standards • group of all 802.11 standards = Wi-Fi Wireless Fidelity • Wi-Fi Alliance • tests wireless devices from manufacturers

11. Components of a WLAN • Wireless client • any host that can participate in a wireless network • Access point (AP) • control access between wired and wireless networks

12. Components of a WLAN • Wireless Bridge • connects two wired networks through a wireless link • offers long range connectivity • 25 miles • Uses unlicensed RF frequencies

13. Access Point • Antennas • increases output signal strength (gain) • receives the wireless signal • higher gain = increased distance • Directional antenna • concentrates signal in one direction • allows for greater distances • Omni-directional antenna • emits signal equally in all directions • used by most Access Points

14. Purpose of SSID • Service Set Identifier • Allows wireless components to connect to the WLAN • tells wireless devices which WLAN they belong to • tells devices whom then can talk to • All wireless devices must have same SSID to communicate with each other • Characteristics • case sensitive • alphanumeric characters • sent in the header of the frame

15. Ad-hoc Installation • Simplest form • Used to connect 2 or more wireless devices together in a peer to peer network • No Access Point (AP) needed • IBSS • Independent Basic Service Set • area covered by the Ad-hoc network

16. Infrastructure Installation • Used by larger networks • Uses an Access Point (AP) • makes sure all STAs have equal access • Each device must receive permission to communicate • BSS • Basic Services Set • area covered by a AP

17. Distribution System • ESS • Extended Service Set • Use of multiple Access Points • Each BSS should overlap by 10% • will help prevent loss of signal

18. Channels in a WLAN • Use of channels help to control conversations • allows multiple Access Points close to one another to function • each AP must be on different channel • Each channel capable of carrying a different conversation

19. CSMA/CA • Carrier Sense Multiple Access with Collision Avoidance • Ensures collisions do not occur on a wireless network • Reserves a channel for communication • Device requests permission from AP (Request to Send–RTS) • If available, AP responds with all clear message • Clear to Send Message (CTS) • CTS is broadcast to all other devices • informs everyone the channel is being used • Upon completion of conversation • Device that requested channel send ACK to AP • ACK indicates to AP that channel can be used again • ACK sent to other devices letting them know the channel can be used again

20. Configuring a Wireless Access Point • Modes • Specific to a device • Mixed Mode – supports multiple types of hosts • decreases performance – supports more devices • SSID • used to identify the WLAN • all devices that participate must use the same SSID • SSID broadcast to everyone • allows for easy detection • Wireless Channel • auto locate • finds the least congested channel

21. Configuring a Wireless Client • Wireless host (STA) – device that contains a wireless NIC and wireless software • client configuration must match that of the Access Point • Windows XP • wireless client software • included as part of the operating system • can control most configurations

22. Configuring a Wireless Client • Using stand-alone software • supplied with the wireless NIC • includes enhanced functions • Not possible to allow both XP and the stand-alone software at the same time • Once software is installed, check connectivity • connection data rate • connection status • wireless channel used • ping

23. Wireless Security • No physical connection needed • Attacker can “tune into” your network just like tuning into a radio station • Easy access if all settings are set to default, so . . . • CHANGE THE SETTINGS • disable SSID • change default password • change default IP • But . . • SSID transmitted in clear text • still possible to learn the SSID

24. MAC Address Filtering • Another security feature • Will limit access to your network • MAC address used to identify which device can connect to the wireless network • wireless AP looks up MAC in a list (database) • only those addresses listed will gain access

25. Security – Authentication • Controls who connects to the network • Permitted based on set of credentials • Helps to verify the “trustworthiness” of the device • usernames • passwords • Occurs before client is connected to WLAN

26. Open Authentication • On by default • Any and all clients can access AP • Should only be used on public wireless networks • Schools • Internet Café

27. PSK (Pre-Shared Keys) Authentication • Both AP and client must have the same secret key or word • Here’s how it works: • AP sends random string of bytes to client • Client accepts it, encrypts it, and sends it back to AP • AP receives encrypted string, decrypts it • if decrypted string = original string  client is added

28. EAP (Extensible Authentication Protocol) • EAP software must be installed on the client device • Client talks with RADIUS Server • Remote Authentication Dial-in User Services • server functions separately from the AP • server keeps a database of valid users • username and password checked by the server

29. Encryption • Process of transforming data so if intercepted, will still be unusable • WEP (Wired Equivalency Protocol) • advanced security feature • encrypts network traffic as it travels • 64 – 128 bits (letters and/or numbers) • AP and every device on the network must have the same WEP key

30. Traffic Filtering • Controls the type of traffic allowed across a WLAN • Able to block traffic based on: • IP Address • MAC Address • Port Numbers

31. Planning the WLAN • Determine the type of wireless standard • 802.11b, g, n operates at 2.4 GHz • travels farther than 5 GHz • Less equipment = lower cost • Determine layout • look at existing infrastructure • if using 802.11a, will it work with the newest standards?? • Installation/Security • Total Cost of Ownership (TCO) • Site Survey • signal strength • possible interference • Backup/Updating Devices

32. Securing the AP • Basic Security • Changing values (SSID, usernames, passwords) • Disable Broadcast SSID • MAC Address filtering • Advanced Security • Encryption • Authentication • Traffic Filtering

33. Configure an Integrated Wireless Access Point and Wireless Client • Describe options for backing-up and restoring AP configurations

34. Configure an Integrated Wireless Access Point and Wireless Client • Identify current version of firmware and describe how to update firmware

35. Summary • Wireless technologies use electromagnetic radiation in the form of radio signals to carry information between devices. • Ease and convenience of connecting devices wirelessly creates security concerns that need to be addressed. • Before installing wireless devices, an installation plan should be created which includes strategies for layout and security.