7 - 1 Session 7 Wireless Security

7 - 2 Wireless LANs (WLANs) Use radio or infrared frequencies to transmit signals through the air (instead of cables) Basic Categories –Use of Radio frequencies (FOCUS of this chapter) 802.1x family of standards (aka, Wi-Fi) –Use of Infrared frequencies (Optical transmission) Wi-Fi grown in popularity –Eliminates cabling –Facilitates network access from a variety of locations –Facilitates for mobile workers (as in a hospital) –Used in 90 percent of companies

7 - 3 Principal WLANs Technologies WI-FI –IEEE b Standardization started after.11a, but finished before, more commonly used than.11a –IEEE a First attempt to standardization of WLANs; more complicated than.11b –IEEE g i – Wifi Protected Access using 256 bit key Bluetooth –Also an IEEE standard

7 - 4 Components of WLANs Network Interface Cards –Available for laptops as PCMCIA cards –Available for desktops as standard cards –Many laptops come with WLAN cards built in –About feet max transmission range Access Points (APs) –Used instead of hubs; act as a repeater Must hear all computers in WLAN –Message transmitted twice »Sender to AP, then AP to receiver

7 - 5 More on the APs and NICs 3 separate channels available for b –All devices using an AP must use the same channel WLAN functions as a shared media LAN –Reduces the interference –Users can roam from AP to AP Initially NIC selects a channel (thus an AP) –Based on “strength of signal” from an AP During roaming, if NIC sees another AP with a stronger signal, attaches itself to this AP Usually a set of APs installed to provide geographical coverage and meet traffic needs –NICs selects a less busy channel if its current channel becomes busy (too many users)

7 - 6 WLAN Topology A wireless Access Point (AP) connected into an Ethernet Switch Same as Ethernet Physical star Logical bus Use the same radio frequencies, so take turns using the network Uses a NIC that transmits radio signals to the AP 10Base-T or 100Base-T

7 - 7 Antennas used in WLANs Omni directional antennas –Transmit in all directions simultaneously –Used on most WLANs Dipole antenna (rubber duck) –Transmits in all direction (vertical, horizontal, up, down) Directional antennas –Project signal only in one direction Focused area; stronger signal; farther ranges –Most often used on inside of an exterior wall To reduce the security issue –A potential problem with WLANs

7 - 8 Types of Antennas

7 - 9 WLAN Radio Frequencies WLANs use radio transmissions to send data between the NIC and the AP Most countries use the 2.4 GHz range and the 5 GHz range The larger the frequency range, the greater the bandwidth, or capacity It is important to ensure that VLAN AP’s do not conflict with each other Therefore, each AP is set up to transmit on a different part of the 2.4 or 5 GHz frequency range

A WLAN Using Different Channels

Bluetooth (IEEE ) A standard for Wireless Personal Area Network (WPAN) –Provides networking in a very small area Up to 10 meters (current generation) Up to 100 meters (next generation) –Includes small (1/3 of an inch square) and cheap devices designed to Replace short distance cabling between devices –Keyboards, mouse, handsets, PDAs, etc –Provides a basic data rate of 1 Mbps Can be divided into several voice and data channels

Copyright 2007 John Wiley & Sons, Inc Multistory WLAN Design Must include –Usual horizontal mapping, and –Vertical mapping to minimize interference from APs on different floors

Copyright 2007 John Wiley & Sons, Inc WLAN Security Especially important for wireless network –Anyone within the range can use the WLAN Finding a WLAN –Move around with WLAN equipped device and try to pick up the signal –Use special purpose software tools to learn about WLAN you discovered Wardriving – this type reconnaissance Warchalking – writing symbols on walls to indicate presence of an unsecure WLAN

Copyright 2007 John Wiley & Sons, Inc Wi-Fi Protected Access (WPA) –new standard –longer key, changed for every packet i –uses AES encryption - WPA 2: The actual key used for message encryption is a derivative of the access point’s assigned key, a random number generated by the access point, as well as the MAC addresses of the access point and the remote device I WPA

Smart Phone Security BBM uses a common symmetric key, low security. Better than plain text. Blackberry Enterprise Server uses a unique Triple DES or AES key for each device. RIM does not have the key. Other smart phones using Exchange Active Syn can enforce symmetric encryption

Copyright 2007 John Wiley & Sons, Inc Implications for Management WLANs becoming common place –Access to internal data, any time, any place Better protection of corporate networks –Public access through WLAN hotspots Competition and overlap with cell phone technologies –New cell phone technologies (faster, longer ranges) –Drastic price drops of WLAN devices Widespread Internet access via multiplicity of devices (PDAs, etc,) –Development of new Internet applications New companies created; some old ones out of business –Drastic increase in the amount of data flowing around