7: Wireless TechnologiesNetworking for Home & Small Business

Objectives

Wireless

Technologies

Understanding Wireless

• Electromagnetic Spectrum– Radio, TV, Light, X-Rays, Gamma Rays– Each has a specific wavelength

• Like the distance between waves

• Wireless uses Electromagnetic Waves– Same as carrying radio signals

• We’ll discuss the most common wavelengths

Infrared (IR)

• Low energy• Can’t go through walls, short range (30’)• One to one communication

– Wireless Mice & Keyboards, Remotes, PDA– Infrared Direct Access (IrDA) port

IR & Your TV• Your TV remote has an infrared LED inside• Switches on & off to create 0’s and 1’s when you

push a button– Push a button to send a 7 digit sequence of 0’s & 1’s– Sony TV Channel Up is 0000011, channel down is

0010001

Radio Frequency (RF)• Wireless LAN, cordless phone, Bluetooth

• LAN & Phone– Signal travels through walls, longer range, higher power– 900 MHz, 2.4 GHz and the 5 GHz frequency

• Bluetooth– Low speed, short range, lower power– One to many devices– Uses 2.4GHz– Starting to use Bluetooth for wireless mice, etc.

Activity- Which is it?

Review

• Bluetooth or RF. Which has higher power output?– RF

• Two doctors are beaming their business cards to each other through their PDAs. Which signal is being used?– IR

Wireless Benefits

Wireless Limitations

• Many devices use wireless– Cordless Phones 2.4GHz Interference– Microwave Ovens Interference– Range– Solid Walls a problem

• Not as fast as wired• Security

– Ease of Access– Authentication & Encryption now used

Wireless Networks

• Grouped into three categories• Hard to place boundaries

WPAN- SMALLEST

• Wireless Personal Area Network– Used to connect wireless mice, keyboards &

PDA’s to computer– IR or Bluetooth– Short Range– Device to device

WLAN

• Wireless Local Area Network– RF– IEEE 802.11 standards– Users connect to a wired network through an

Access Point (AP)– Medium range

Access Point

• Between your wired equipment and your wireless devices

WWAN

• Wireless Wide Area Network– Cell phone network– GSM, CDMA– Long range– Government regulated

Wireless Networks

Review

Wireless

LANs

Wireless Standards

• Specifies data speed, range, RF spectrum• IEEE standards, Wi-Fi• 802.11a, 802.11b, 802.11g and 802.11n

• Wi-Fi Alliance tests devices from manufacturer

• Will work with other devices w/ same logo

802.11b

• 1999• 2.4GHz• 11Mbps• 150ft range

indoors• 300 ft range

outdoors

802.11a• 1999• 5GHz

– Unused at that time – Less congestion

• 54Mbps (faster than B)• NOT compatible with b/g/n• 75ft-150ft range• Originally too expensive• Now hard to find

802.11g

• 2003• 2.4GHz• 54Mbps• 150ft range indoors• 300 ft range outdoors• Compatible with 802.11b

802.11n

• 2.4Ghz• Up to 750ft range• Backwards compatible b/g

Wireless Components

• Access Point– Connects wireless devices to wired network

• Client– Any host device that connects to wireless– Also known as STA (station)

• Bridge • Antenna

Omni-Directional Antenna

• Equally in all directions• Found on APs

Directional Antenna

• Concentrate signal in one direction• Better distance• Connects networks 25 miles or more apart• Bridge to Bridge- connects 2 networks

wirelessly

Want a bridge? Aironet 1400

• Find it on www.cdwg.com

Activity

WLANs & the SSID

• Your WLAN has to be identified

SSID-Service Set Identifier• Tells wireless devices which WLAN they belong

to & which other devices they can communicate with

• Case-sensitive & up to 32 characters• All of your devices MUST have same SSID

– Broadcast or Not?

WLAN Install 1:Ad-hoc Mode- IBSS

• Wireless devices can talk to each other without involving Access Point

• Peer-to-peer or small networks• Less $$$, no AP

WLAN Install 2: Infrastructure Mode- BSS

• Most used• AP/Router controls communication

– Access to Internet– Basic Service Set (BSS)

• Area covered by a single AP

Cover More Areas

• Connect many BSS’s to get expanded area– You get an ESS, Extended Service Set

• Areas should overlap– Think about this school & coverage

Question?

Question?

Question?

Question?

Lab Activity

• 7.2.3.4• READ THE INSTRUCTIONS!!!• Click Topology, then the host• View browser, follow directions

Wireless Channels• Used to control multiple conversations

– Like how all of your TV channels travel across a cable– Divides up the 2.4GHz for each conversation

• Selection of channels is usually automatic

• Sometimes they use a single wide channel to get more bandwidth

Going to a Concert

• General Admission compared to tickets for a seat– What’s the different experiences?

• Wireless has a method to avoid collisions• A “ticketing” system

Wireless Detecting Collisions

• CSMA/CA• Reserves a channel for conversation

– No one else may use that channel• Request to Send (RTS) to the AP• If available, a Clear to Send (CTS) is sent

– OK to send– Broadcast is sent to all, notifying channel in

use• ACK sent to AP to notify done

– All devices see ACK & know channel is open

CSMA/CA- (7.2.4.2)

Activity- Setting the Channel

• 7.2.4.3

Configuring an AP

Configuring the Client

• What is a wireless host known as?– STA (station)

• It’s a device with wireless NIC & software for it

• Settings MUST match AP– SSID, security settings, and channel

Configuring the Client- Software

• As part of the OS• OR supplied with Wireless NIC

– Contains link info, profiles, etc.

• Usually the OS one is okay

Now Test It…• Look at signal strength• Then test data transmission

– Use the ping test– Ping another PC 1st

– If that doesn’t work, ping the AP

Lab 7.2.5.3 & 7.2.6.4

• Configure the AP and Wireless Client

Security on

Wireless

LANs

Wireless Security

• Tradeoff:– Ease & convenience of availability vs. putting

info to the airwaves• What can they do?

– Use your Internet for FREE– Access your computers– Damage files– Steal private info

• Solution…SET UP SECURITY!

Why is security important?

• It’s possible that an individual or a business owner can be held responsible for what an unauthorized user does with your network

• Computer Fraud Law– Accessing a computer without authorization

Getting In Easily

Which Security Measures??

• Use all of the following to secure your wireless network:

1. Change the router password from the default

2. Change the SSID & disable the broadcast

3. Use MAC Address Filtering

4. Authentication (PSK)

5. Encryption (WPA)

Change the Password!

Change SSID & Disable Broadcast

• SSID– Must be known to connect– Broadcast by default

• Solutions– TURN SSID BROADCAST OFF!!– Change the default settings

• SSID• Passwords• IP addresses

– These solutions help, but you can still be hacked!

The SSID’s- Discovered!!!

Get your MAC Addresses

Set up MAC Address Filtering

MAC Address Filtering

• Use your device’s MAC address to limit connectivity to you KNOWN devices

• You pre-configure the MACs in the AP• The AP will check its list• Only those in list will connect

MAC Address Filtering

• What could go wrong?– Typo on the MAC address– New devices can’t enter network without

adding Mac to the AP configuration– MAC address cloning

1. Sniff network traffic (MAC address in packet)

2. Find MAC addresses on that network

3. Change your MAC address to match one on the target network.

Sniffing to Clone

Authentication• Permitting entry on WLAN based on credentials

• Used before connecting to the WLAN– Checks authentication 1st

– Then MAC address filtering

1. Open authentication (DEFAULT SETTING)

2. PSK (good)….THIS IS USED AT HOME.

3. EAP (better than PSK)…BUSINESSES.

Open Authentication• Public networks

Pre-Shared Keys (PSK)• Client & AP have secret word/keys• One-way

– Client authenticates to the AP– AP DOES NOT authenticate the user

Extensible Authentication Protocol- EAP

• Two-way PLUS user authentication• Uses a separate server (RADIUS)

– Built into some AP’s now– More for medium to large businesses

• The user provides a username & password

Overview

WLAN Encryption

• Protecting data going through the air

• WEP (Wired Equivalency Protocol)• WPA (Wi-Fi Protected Access)

Configuring Auth & Encrypt• WEP• WPA Personal, uses PSK

– TKIP (Temporal Key Integrity Protocol)– AES (Advanced Encryption System)

• WPA2– TKIP or AES

• WPA Enterprise, RADIUS• RADIUS• AES is only supported by newer devices that

contain a co-processor. – To ensure compatibility with all devices, select TKIP.

Problems Still???• Authentication & MAC filtering won’t stop the

hacker– They can sniff the info from the air

• Encrypt the data– WEP– WPA

WEP- Wired Equivalency Protocol

• String of letters & numbers• 64 or 128 bits• Passphrase• All devices in WLAN must have same WEP

key• Can work in conjunction with PSK

– WEP-PSK• WEAK!!!!!

– Static key

WPA- Wi-Fi Protected Access• Better than WEP• 64-256 bits• New keys for each time it connects

Review• WEP/WPA _______________ the data.

– Encrypt• PSK/EAP are used to _____________ the

user to the WLAN.– Authenticate

• WEP or WPA. Which is stronger?– WPA

• What’s the difference between open authentication & PSK?– PSK has the secret key

Activity• 7.3.4• Configure

authentication

Traffic Filtering• You can control the type of data

– Entering or leaving the AP– Going to/from a specific MAC or IP– Block by port #

Lab

• 7.3.5.2• Configuring Wireless Security

Configuring

the AP &

Clients

Planning the WLAN

• Determining the type of wireless standard to use

• Determining the most efficient layout of devices

• An installation and security plan• A strategy for backing up and updating the

firmware of the wireless devices.

Wireless Standard• Bandwidth requirements, coverage areas,

existing implementations, and cost. – This information is gathered by determining end-user

requirements.

• Ask the following… – What throughput is actually required by the

applications running on the network? – How many users will access the WLAN?– What is the necessary coverage area?– What is the existing network structure?– What is the budget?

Planning the WLAN

• Which 802.11 standards support a larger BSS?– Means less equipment to buy

• Is there an existing standard in use?

• Total Cost of Ownership (TCO) which includes the purchase of the equipment as well as installation and support costs

Installation of Devices

• Site Survey– Measurements– Consider interference sources & locations

Install & Secure the AP

Back It Up!!! 7.4.3.2 Activity

• Home & Small Business– Select Backup Configuration in Menu– To restore, select it– Factory Default Setting

Updating the Firmware

• The OS of the device is in firmware– Update for new features, etc

1. Get the current version

2. Research issues & features that may cause you to want the upgrade

3. Download it to a HD (directly connected machine)

4. Select Firmware upgrade• DO NOT INTERRUPT THE PROCESS!

7.4.4.2 Activity

• Upgrade the firmware

Review

7: Wireless TechnologiesNetworking for Home & Small Business