Wireless networking

Unit objectives Identify the hardware components

needed to create a wireless connection

Differentiate between the various communications standards used in wireless networks

Install and configure a wireless network connection

Topic A Topic A: Wireless network devices Topic B: Wireless networking

standards Topic C: Wireless configuration

Wireless Technologies and systems that don’t

use cables for communication Examples

– Public radio– Cellular telephones– One-way paging

Satellite– Infrared– Private, proprietary radio

Wireless networks – LAN or WAN

Wireless connections Can link devices Methods

– Infrared– Radio– Bluetooth

Infrared and Bluetooth– Create wireless connection between two

devices Radio technology

– Forms larger wireless network

Infrared Uses pulses of invisible infrared light

to transmit signals Low-speed, line-of-sight connection Can’t pass through obstructions or

around corners 9600 bps to 4 Mbps data rate 10-20 feet maximum range Devices must aim their transceivers at

each other (line-of-sight technology)continued

Infrared, continued No more than a 45 degree angle Most popular form: Infrared Serial

Data Link technology– Serial connection – 1.5 Mbps– 20 foot range

Often found on laptops and PDAs

Radio Signals sent over electromagnetic

radio waves Can pass through most nonmetallic

obstructions and around corners Not a line-of-sight technology Offers moderate- to high-speed local

and wide area connections Most common technologies:

– 802.11b – 802.11g continued

Radio, continued 10 Mbps Sometimes called RF technologies

– RF stands for radio frequency RF devices have antennae

Bluetooth Short-distance radio (up to 10 meters) Developed by the Bluetooth Special

Interest Group– Includes over 1,000 companies– Siemens, Intel, Toshiba, Motorola, and

Ericsson Enables devices to discover other

Bluetooth devices within range Devices self-configure and begin

communicatingcontinued

Bluetooth, continued Shouldn’t need to configure

communication parameters Bluetooth devices have antenna often

hidden inside the device B l u e t o o t h a d d r e s s

Wireless communications Enables users to

– Make Internet connection while traveling– Connect to network while moving about

house or office Important technology for

– Mobile devices – Internet access in remote locations

Three types of wireless links– Indoor point-to-multipoint LANs– Outdoor point-to-point links– Outdoor point-to-multipoint links

Indoor point-to-mulitpoint LANs

Outdoor point-to-point links

Outdoor point-to-multipoint links

Wireless connection components

Requires– Wireless network card in the computer – Wireless router or wireless access point

device on the network Router or WAP broadcasts radio

signals Wireless network cards pick up the

broadcasts

Wireless NICs

Wireless access points

Wireless speeds Distance and data rate affected by

– Obstructions within building– Environment noise

Recommend wireless LAN access points within 60 to 90 meters of wireless clients

IEEE speed Data rate Distance (meters)

High 4.3 Mbps 40 to 125

Medium 2.6 Mbps 55 to 200 Standard 1.4 Mbps 90 to 400

Standard low 0.8 Mbps 115 to 550

WAP placement Informal site survey

– Temporary installation WAPs– Use wireless client to test signal– Use actual locations for clients

Formal site survey– Use field-strength measuring equipment – Install test antenna in the estimated WAP

locations– Strength of test signal at various points within

the range the WAP will service– Move test antenna to obtain the best possible

signal for the wireless coverage area

Activity A-1

Examining wireless devices

Topic B Topic A: Wireless network devices Topic B: Wireless networking

standards Topic C: Wireless configuration

Standards Frequency bands divisions

– Military– Broadcasters– Amateur radio operators

Broadcast signal is a security issue IEEE standards 802.1x and 802.11

802.1x standard Port-based, authentication framework

for access to Ethernet networks Designed for wired Ethernet networks Applies to 802.11 WLANs Requires three roles in authentication

process– Device requesting access– Authenticator– Authentication server

Allows multiple authentication algorithms

Is an open standard

802.11 standard Operates in the 2.4 through 2.5GHz

band Used for wireless networks OSI Data Link layer Two ways to configure a network

– Ad-hoc – Infrastructure

Places specification on Physical and MAC layers

Access point Transparent bridge between wireless

clients and wired network Includes

– At least one interface to connect to the existing wired network

– Transmitting equipment to connect with wireless clients

– IEEE 802.1D bridging software

802.11 WLAN standards 802.11a 802.11b 802.11c 802.11d 802.11e 802.11F 802.11g

802.11h 802.11i 802.11j 802.11k 802.11l 802.11m 802.11n

Wireless protocols Wi-Fi (Wireless Fidelity)

– IEEE 802.11b: 11 Mbps; 2.4 GHz band – IEEE 802.11g: 20+ Mbps; 2.4 GHz band;

transmission range of up to 35 meters – Experience interference from other

common household devices Bluetooth

– Short-range: about 100 meters or less – Low speeds: 721 Kbps

continued

Wireless protocols, continued 802.11a

– Improved version of original Wi-Fi– 54 Mbps; 5 GHz band– Indoor range of up to 35 meters– Not compatible with 802.11b devices

WiMAX (IEEE 802.16 Air Interface Standard)– Point-to-multipoint broadband access– 10-66 GHz licensed– 2-11 GHz unlicensed– 70 Mbps – 31 miles; direct line-of-site

LAN technologies IEEE 1394

– FireWire (Sony) and iLink (Apple)– Main use: video and graphics transfers– Serial protocol – FireWire 400: 100 to 400 Mbps– FireWire 800: up to 800 Mbps

USB– Bidirectional serial interface – Main use: connect peripheral devices– USB 1.1: 1 to 12 Mbps– USB 2.0: 480 Mbps

Wi-Fi Called AirPort. 802.11b Frequency range of 2.4 GHz Distance range of about 100 meters Up to 11 Mbps Range depends on type of signal

obstructions between transmitter and receiver

802.11b – popular and inexpensive network solution

Many cordless phones use the 2.4-GHz frequency and can interfere with 802.11b network

Bluetooth Standard for short-range wireless

communication and data synchronization between devices

Transmitters and receivers are application-specific integrated circuits (ASICs)

Can transmit data at rates as high as 721 Kbps

Up to three voice channels available Easy to configure

802.11a/802.11g 802.11a

– 5.0-GHz band – Isn’t compatible with 802.11b – 50 meters max between AP and client– Faster than 802.11b – Doesn’t encounter interference from 2.4

MHz devices 802.11g

– 2.4-GHz band – Backwards compatible with 802.11b– 54 Mbps

WiMAX Worldwide Interoperability of

Microwave Access Wireless DSL and T1-level service Emerging Wide Area and Metropolitan

Area Networks technology standard Enables 802.16e devices to roam

between current wireless hot spots Coverage measured in square miles Doesn’t rely on line-of-sight for

connection

Activity B-1

Comparing wireless networking standards

Topic C Topic A: Wireless network devices Topic B: Wireless networking

standards Topic C: Wireless configuration

WLAN security risks Devices can be lost or stolen Session hijacking Man-in-the-middle attacks Rogue AP WAP no default security Broadcasts make breaking in easy IEEE and WECA developed standards

for user authentication and media access control

Additional risks Detectable radio-frequency traffic Data is passed in clear text form Encryption isn’t always strong

– WEP One-way authentication mechanism One-way open broadcast client

connection Wardriving Warchalking

WLAN security components Access control

– Turn off SSID broadcasts– Enable a MAC filter on your AP

Encryption– Clients and AP use same encryption

scheme – Clients must possess correct encryption

key– Wireless encryption systems vary in

ability to keep data securecontinued

WLAN security, continued Authentication

– Server authenticates clients– Stronger access control protection than

SSID hiding or MAC filtering – Should still use encryption

Isolation– Segregates network traffic– Two types: wireless client isolation (AP

isolation) and network isolation– Network isolation through custom routing– Isolation through your general network

design and firewall configuration

Transmission encryption Wired Equivalent Privacy (WEP) Wi-Fi Protected Access (WPA)

Personal WPA2 WPA Enterprise RADIUS 802.11i

802.1x authentication

Activity C-1

Identifying the technology used to implement WLANs

Wireless access point configuration

Assign a service set identifier (SSID)– Clients use the SSID to distinguish

between WLANs AP typically broadcasts the SSID

– Broadcasts identify the security mechanisms to enable clients to auto-configure connections

Securing your AP Set most secure encryption method

compatible with clients Change AP default admin passwords Change default SSID Disable SSID broadcasts Separate wireless network from wired

network Put wireless network in an Internet-

access only zone or DMZ continued

Securing your AP, continued Disable DHCP within WLAN Enable MAC address filtering on AP Enable 802.1x Periodically survey site with wireless

sniffing tool

Activity C-2

Configuring a wireless access point (instructor demo)

Wireless clients Submit its credentials to the Authenticating

server Secured or 802.1x authenticated

connections– Wireless AP issues a challenge to the client– AP sets up restricted channel allowing client to

communicate only with RADIUS server– RADIUS server accepts only trusted AP

connections– RADIUS server validates the client credentials– Transmits client master key to wireless AP

Wireless Auto Configuration Dynamically selects wireless network

connection attempt Based on

– Configured preferences – Default settings

Wireless Zero Configuration – Windows Vista – Windows XP– Windows 2000 with download

Automatically configures address items:– TCP/IP settings,– DNS server addresses– IAS server addresses

Auto Configuration, continued IEEE 802.1x authentication defaults

– Infrastructure before ad hoc mode– Computer authentication before user

authentication.– If NIC is preconfigured with WEP shared

key, attempts to perform IEEE 802.11 shared key authentication; otherwise NIC reverts to open system authentication

Windows CE wireless clients Windows CE .NET palm-top

computers include Wireless Zero Configuration

Manual configuration options similar to those found on Windows Vista and Windows XP

Supports 802.11a and Native Wireless Fidelity (Wi-Fi)

Non-.NET palm-tops wireless configuration is like Windows 2000

Activity C-3

Configuring a wireless client (instructor demo)

Unit summary

Identified the hardware components needed to create a wireless connection

Differentiated between the various communications standards used in wireless networks

Installed and configured a wireless network connection