© 2007 Cisco Systems, Inc. All rights reserved.Cisco Public ITE PC v4.0 Chapter 1 1 Wireless Technologies Networking for Home and Small Businesses – Chapter 7

ITE PC v4.0 Chapter 1 2 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Objectives  Describe wireless technologies.  Describe the various components and structure of a WLAN  Describe wireless LAN security issues and mitigation strategies  Configure an integrated wireless access point and a wireless client.

ITE PC v4.0 Chapter 1 3 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public  All use waves in Electromagnetic spectrum to transfer information from device to device.  Electromagnetic spectrum includes bands used for radio, TV, and visible light.

ITE PC v4.0 Chapter 1 4 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public How Big?

ITE PC v4.0 Chapter 1 5 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Overview of Waves  Wave is a “disturbance or variation” that travels through a medium.  The medium through which the wave travels may experience some local oscillations as the wave passes, but the particles in the medium do not travel with the wave. Just like none of the individual people in the stadium are carried around when they do the wave, they all remain at their seats. Rick Graziani

ITE PC v4.0 Chapter 1 6 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Waves  Waves are one way in which energy can move from one place to another.  The waves that you see at the beach are the result of the kinetic energy of water particles passing through the water.  Other types of energy (such as light, heat, and radio waves) can travel in this way as well. Rick Graziani

ITE PC v4.0 Chapter 1 7 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Waves  The distance between 2 peaks (or 2 troughs) is called a wavelength  The deepest part of a trough or the highest part of a peak is called the amplitude  The frequency is the number of wavelengths that pass by in 1 second Rick Graziani

ITE PC v4.0 Chapter 1 8 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Longitudinal Waves  Longitudinal sound waves in the air behave in much the same way.  As the sound wave passes through, the particles in the air oscillate back and forth from their equilibrium positions but it is the disturbance that travels, not the individual particles in the medium.  Rick talks in a loud voice.  When he talks he causes the air near his mouth to compress.  A compression wave then passes through the air to the ears of the people around him.  A longitudinal sound wave has to travel through something - it cannot pass through a vacuum because there aren't any particles to compress together.  It has a wavelength; a frequency and an amplitude. Rick Graziani

ITE PC v4.0 Chapter 1 9 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Transverse Waves  Transverse waves on a string are another example.  The string is displaced up and down, as the wave travels from left to right, but the string itself does not experience any net motion.  A light wave is a transverse wave.  If you look at the waves on the sea they seem to move in one direction.... towards you.  However, the particles that make up the wave only move up and down.  Look at the animation, on the right, although the wave seems to be moving from left to right the blue particle is only moving up and down. Rick Graziani

ITE PC v4.0 Chapter 1 10 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Sine waves  The sine wave is unique in that it represents energy entirely concentrated at a single frequency.  An ideal wireless signal has a sine waveform  With a frequency usually measured in cycles per second or Hertz (Hz).  A million cycles per second is represented by megahertz (MHz).  A billion cycles per second represented by gigahertz (GHz). Rick Graziani

ITE PC v4.0 Chapter 1 11 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Sine waves  Amplitude – The distance from zero to the maximum value of each alternation is called the amplitude. The amplitude of the positive alternation and the amplitude of the negative alternation are the same.  Period – The time it takes for a sine wave to complete one cycle is defined as the period of the waveform. The distance traveled by the sine wave during this period is referred to as its wavelength.  Wavelength – Indicated by the Greek lambda symbol λ. It is the distance between one value to the same value on the next cycle.  Frequency – The number of repetitions or cycles per unit time is the frequency, typically expressed in cycles per second, or Hertz (Hz). Rick Graziani

ITE PC v4.0 Chapter 1 12 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Relationship between time and frequency  The inverse relationship between time (t), the period in seconds, and frequency (f), in Hz, is indicated by the following formulas: t = 1/f (time = 1 / frequency) f = 1/t (frequency = 1 / time) Examples: 1 second  t = 1/f 1 second = 1 / 1 Hz (1 cycle per second)  f = 1/t 1 Hz = 1 / 1 second ½ second  t = 1/f ½ second = 1 / 2 Hz (2 cycles per second)  f = 1/t 2 Hz = 1 / ½ second 1/10,000,000 th of a second  t = 1/f 1/10,000,000 th of a second = 1 / 10,000,000 Hz (cycles/sec) = 1 / 10 MHz  f = 1/t 10 MHz = 1 / 1/10,000,000 th of sec Rick Graziani

ITE PC v4.0 Chapter 1 13 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Sine waves  One full period or cycle of a sine wave is said to cover 360 degrees (360°).  It is possible for one sine wave to lead or lag another sine wave by any number of degrees, except zero or 360.  When two sine waves differ by exactly zero° or 360°, the two waves are said to be in phase.  Two sine waves that differ in phase by any other value are out of phase, with respect to each other. 180° Phase Shift Amplitude, Frequency, and Phase Rick Graziani

ITE PC v4.0 Chapter 1 14 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Analog to digital conversion 1.Analog wave amplitudes are sampled at specific instances in time. 2.Each sample is assigned a discrete value. 3.Each discrete value is converted to a stream of bits. Rick Graziani

ITE PC v4.0 Chapter 1 15 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Bandwidth  There are two common ways of looking at bandwidth: Analog bandwidth Digital bandwidth  Analog bandwidth Analog bandwidth can refer to the range of frequencies. Analog bandwidth is described in units of frequency, or cycles per second, which is measured in Hz. There is a direct correlation between the analog bandwidth of any medium and the data rate in bits per second that the medium can support. Rick Graziani

ITE PC v4.0 Chapter 1 16 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Bandwidth  Digital bandwidth Digital bandwidth is a measure of how much information can flow from one place to another, in a given amount of time. Digital bandwidth is measured in bits per second. When dealing with data communications, the term bandwidth most often signifies digital bandwidth. Rick Graziani

ITE PC v4.0 Chapter 1 17 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Unlicensed Radio bands in Hz

ITE PC v4.0 Chapter 1 18 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Wireless Technologies  Infrared Band (IR) Low energy and unable to penetrate walls (line of sight) Could this be a benefit? Used for PDAs, PCs, wireless mice, keyboards and remote controls IrDA (Infrared Direct Access) port used for 1 to 1 connections  Radio Frequency (RF) Goes through walls and other obstructions, better range Different frequencies assigned to different types of unlicensed devices (900MHz, 2.4GHz, 5GHz) Cordless Phones Problem with 900MHz? Used for military and civilian emergency bands outside US Wireless LANs Computer Peripherals Bluetooth uses 2.4 GHz band for low-speed, short-range, many devices at once

ITE PC v4.0 Chapter 1 19 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Wireless Technologies Pros  Provide anytime, anywhere connectivity  Hotspots implemented globally  Easy and inexpensive to install  Enables networks to be easily expanded, i.e., ease of adding additional devices Cons  Unlicensed regions of the RF spectrum – congestion and interference common  Security. Wireless provides ease of access – through broadcasts

ITE PC v4.0 Chapter 1 20 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Interference

ITE PC v4.0 Chapter 1 21 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Wireless Technologies  Pros Anytime, anywhere connectivity with hotspots Easy and cheap installation Device prices dropping Data rate capabilities increasing Easy expansion  Cons Unlicensed RF which is crowded with other devices Bluetooth Microwaves Cordless phones Security is difficult because there is no way to limit who can intercept the wireless signal Encryption helps, but can be defeated Fluctuations in temperature and humidity can really affect transmission range.

ITE PC v4.0 Chapter 1 22 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Station Connectivity

ITE PC v4.0 Chapter 1 23 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public  Wireless networks are difficult to categorize because boundaries cannot be precisely defined.

ITE PC v4.0 Chapter 1 24 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Wireless Network Technologies  Technologies used for the different network types:

ITE PC v4.0 Chapter 1 25 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public  Many different standards have been adopted for wireless networks Wi-Fi Alliance tests devices from various manufacturers to make sure they operate together. The device is interoperable with other devices of the same standard. ProtocolRelease Date RF Freq. Through put Data Rate (Max) Max Range Notes & Comments GHz0.9 Mbps2 MbpsUndefinedLegacy a GHz23 Mbps54 Mbps50m  Not compatible with b, g, n  Expensive b GHz4.3 Mbps11 Mbps100mFirst 2.4 GHz Technology g GHz19 Mbps54 Mbps100mBackward compatible with b Shares range with b n 2009 * 2.4 & 5 GHz 74 Mbps248 Mbps250mNewest Standard y 2008 * 3.7 GHz23 Mbps54 Mbps5000mNewest Standard

ITE PC v4.0 Chapter 1 26 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Wireless Technologies  Wireless networks and their boundaries They are unlike Bluetooth technology in that they transmit at a much higher power level, which gives them a greater range.

ITE PC v4.0 Chapter 1 27 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Components and Structure of a WLAN  Identify and describe wireless LAN standards

ITE PC v4.0 Chapter 1 28 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public  Wireless Components Wireless Clients or STAs (Wireless STAtion) APs (Access Points) Wireless Bridges  Types of Antennas Omni send all directions Used in APs Directional send in one direction Used for longer links to bridge distances

ITE PC v4.0 Chapter 1 29 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public  The Service Set Identifier (SSID) used by components to connect to a particular WLAN. 32-byte Alphanumeric String Used in Frame Headers  Two forms of WLAN Installations Ad-hoc - IBSS Equal Peer-to-peer No AP Infrastructure - BSS STAs communicate through APs BSS is an area with a single AP

ITE PC v4.0 Chapter 1 30 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Components and Structure of a WLAN  Describe how wireless channels are used  CSMA/CA: Describe how wireless channels avoid collisions Extended Service Set (ESS)

ITE PC v4.0 Chapter 1 31 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Wireless Channels  Channels are created by giving each a part of the RF spectrum Each one can carry on a separate conversation (Think of a TV) Can be set manually or automatically  Channels will often overlap frequencies, but conversations cannot overlap  Newer technologies combine channels into a wider one for better bandwidth

ITE PC v4.0 Chapter 1 32 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public b/g channel use HR/DSSS uses 22 MHz channels in the 2.4 to GHz range. This allows for three non-overlapping channels (three channels that can coexist or overlap without causing interference), channels 1, 6 and 11

ITE PC v4.0 Chapter 1 33 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public a channel use  Offers 8 lower and mid-band non-interfering channels As opposed to 3 with b/g

ITE PC v4.0 Chapter 1 34 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public

ITE PC v4.0 Chapter 1 35 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public  A WLAN technology designed to make collisions impossible  Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA). Reserves a channel for use by a conversation No other devices can transmit on that channel  CSMA/CA Reservation Process For a Device to use a channel, it asks the AP by using a Request To Send (RTS) message. If channel is not in use, AP will send Clear To Send (CTS) message to all devices in the BSS so they know the channel is being used. Data is sent from STA After conversation is done, an Acknowledgement (ACK) is transmitted.

ITE PC v4.0 Chapter 1 36 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public  Integrated wireless access point Network Mode b, g, or a different technology SSID Name of your wireless network Standard Channel Default is AUTO, but this decides which channel will be used SSID Broadcast Sends out the SSID to the world Default is ENABLE The router supports b, g, and n devices

ITE PC v4.0 Chapter 1 37 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Components and Structure of a WLAN  Configure an integrated wireless access point

ITE PC v4.0 Chapter 1 38 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Wireless Client Configuration  Client software allows hardware to connect to the WLAN.  For connection to occur, the SSID, security settings, and channel must match the AP.  Wireless Utility Software usually comes with the NIC  Some features Link Information: strength and quality of signal Profiles: specify configuration options Site Survey: checks for all WLANs in the area To use the vendor software, Windows XP wireless software must be disabled.  For most purposes, XPs built-in wireless drivers can be used.

ITE PC v4.0 Chapter 1 39 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Components and Structure of a WLAN  Configure a wireless client

ITE PC v4.0 Chapter 1 40 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public  One large benefit to Wireless networks is also biggest vulnerability: transmission of information through the air.  Attacks don’t need physical access to equipment, just be in range. War Driving or Walking to discover insecure networks  If they gain access, an attacker can: Use your Internet for free Hack your computers or files  Special security protocols have been developed to protect networks, but there are simple steps as well. Disable the SSID broadcast so that your network isn’t public. Change your default settings IP Address Router Name Admin Password

ITE PC v4.0 Chapter 1 41 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public  Controls exactly which devices have access to the LAN  Uses MAC addresses to ID clients authorized to access WLAN.  Limitations: MAC addresses for authorized clients must be input manually. This makes adding new clients difficult MAC Address cloning or spoofing can allow an unauthorized user to get into the WLAN.

ITE PC v4.0 Chapter 1 42 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public  This process requires a client to present credentials in order to use the network.  Most common is a username and password, but for a wireless network, this is handled differently.  Because the transaction is wireless and can be “heard” by anyone, the authentication is done before connecting.  Three Types of Authentication: Open Used for Public Networks Networks where another method of authentication is used. PSK EAP

ITE PC v4.0 Chapter 1 43 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Wireless LAN Security - Authentication  PSK (Pre-Shared Key) Both client and AP are configured with a shared key Password is encrypted by client using shared key, then sent to AP, where it is decrypted using the same key. Doesn’t authenticate AP or User, only one way  EAP (Extensible Authentication Protocol) Authentication is 2-way Client communicates through AP to (usually) a RADIUS server which has list of authorized users and clients. Both user and client must authenticate.

ITE PC v4.0 Chapter 1 44 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public  Use of Wireless Authentication Authentication can prevent unauthorized users from accessing WLAN, but data is still transmitted to anyone with a receiver. Encryptions methods were developed to encrypt wireless communications to prevent snooping by outsiders.  Two main encryption methods: WEP (Wired Equivalency Protocol) Uses pre-configured 32, 64, 128, or 256 bit keys to encrypt data before transmission. WEP keys are just a string of letters or numbers and can also be automatically generated using a passphrase. WEP is not a secure protocol and can easily be cracked by a knowledgeable wireless hacker. WPA (Wi-FI Protected Access) Also uses a 64 to 256 encryption key. WPA doesn’t always use the same key, but generates new, dynamic keys each time a client connects. WPA is considered the current standard of encryption for wireless networks.

ITE PC v4.0 Chapter 1 45 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Wireless LAN Security Issues and Mitigation Strategies  Describe traffic filtering and its purpose

ITE PC v4.0 Chapter 1 46 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Planning the WLAN  Plan for a wireless LAN implementation

ITE PC v4.0 Chapter 1 47 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public  Security should be planned and configured before installing into network or ISP  Basic measures: Change Defaults for SSID, usernames, and PWs Disable SSID broadcast MAC Address Filtering  Advanced Measures WPA or WEP Encryption Authentication Traffic Filtering

ITE PC v4.0 Chapter 1 48 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Configure an Integrated Wireless Access Point and Wireless Client  Describe options for backing-up and restoring AP configurations

ITE PC v4.0 Chapter 1 49 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public  Configuration files for APs are stored in their non-volatile memory  Any stored memory can be corrupted, so it’s important to backup the configuration in case of problems.  Backup Save the configuration file to a secure location  Restore Use the restore button to upload the file to the AP  Setting to Factory Default Menu option Hold RESET button for up to 30 seconds.

ITE PC v4.0 Chapter 1 50 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public  Firmware is a basic OS for the AP or Router stored in flash memory  Can be updated using the GUI on the AP/Router Download from manufacturer’s website Make sure to check version currently being used  NEVER interrupt an update while it is being uploaded, it may make the AP/Router unusable.

ITE PC v4.0 Chapter 1 51 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Configure an Integrated Wireless Access Point and Wireless Client  Identify current version of firmware and describe how to update firmware

ITE PC v4.0 Chapter 1 52 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Challenge Lab 7-4: Planning the Home or Small Business WLAN  Objectives Evaluate user needs Use a WLAN implementation checklist Conduct a mini-site survey Plan WLAN implementation

ITE PC v4.0 Chapter 1 53 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public 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.

ITE PC v4.0 Chapter 1 54 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public