Wireless Networks Tamus, Zoltán Ádám

Basics of Communication  Transmitter (coding)->Channel->(decoding) Receiver

The Radio-Channel  Wireless technologies use electromagnetic waves as channel  Radio waves (freq. 30 kHz-30 GHz)  Light (Infra Red) (wavelength ~900 nm)

Personal Area Networks  Interconnecting devices without wire  Headsets  Notebooks  PDA (Personal Digital Assistant)  Mobile phones  GPS  Peripherals (Keyboard, Mouse, Printer, Game controller etc.)

 Bluetooth  1998, Special Interest Group (Ericsson, IBM, Intel, Nokia, Toshiba)  Uses radiofrequency: in the 2.4 GHz band, frequency hopping spread spectrum system  Max. 1 Mb/sec bandwidth  Operating range ~10 m, but in high power applications can be extended to 100 m Personal Area Networks

Personal Area Network  Bluetooth devices

Personal Area Network  IrDA (Infrared Data Association) 1993  Use Infrared light  Operating range max. 1 m  Bandwidth: 4 Mb/sec.

Local Area Networks  Home  Offices  Public WLAN, Wi-Fi Hot Spots  Hotels  Airports  Net Cafes  Ad Hoc peer to peer

Local Area Network  Typical WLAN application in home or small office

Local Area Network  Network Access in Buildings  Desktop PCs  Notebooks  PDAs

Local Area Networks  IEEE standard  a  1999  5 GHz band  Max. 54 Mb/sec  b  2.5 GHz  Max. 11 Mb/sec  g  2.5 GHz  Max. 54 Mb/sec

Security  Eavesdropping & Espionage  Wireless technologies use radio waves. Eavesdroppers can easily pick up unencrypted messages by listening the ether  Rouge Access Points  An employee of an organization might hook up an access point without the permission or even knowledge of IT.

 Accidental Associations  A wireless network is setup using the same SSID as your network and within range of your wireless device. Connecting to another wireless LAN can divulge passwords or sensitive document to anyone on the neighbouring network  Denial of Service  Flowing packages to the network take the resources  RF interference with an external transmitter Security

Security  Securing Wireless Networks  WEP (Wired Equivalent Privacy)  Problems: Easily vulnerable because of the permanent keys and the short initialization vector  WPA (Wi-Fi Protocol Access)  The clients use periodically changed different keys  VPN (Virtual Private Network)

 Authentication  SSID (Service Set Identifier)  Weakness in IEEE : the SSID is sent without encrypting!  MAC address filtering  MAC (Media Access Control)  WEP not encodes the MAC field of the frame! Security

Setting up a wireless router  Connection to the broadband router  Connecting a PC

 Access to Web-based utility software by Router’s IP address  User Name:  User Name:  Password: admin Configuration

Setting up Internet Connection  DHCP  Static IP  PPPoE  PPTP

Setting up Wireless Network  Mode: B/G  SSID Broadcasting ?  Channel

Security Settings  WEP  Level of WEP encryption: 64-bit or 128-bit

 WPA  WPA2  WPA2 Mixed  Set the Passphrase and Renewal period Security Settings

Access control  MAC address filtering

Security Precautions   Change the default SSID.   Disable SSID Broadcast.   Change the default password for the Administrator account.   Enable MAC Address Filtering.   Change the SSID periodically.   Use the highest encryption algorithm possible. Use WPA if it is available. Please note that this may reduce your network performance.   Change the WEP encryption keys periodically.