© 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 Wireless Technologies  The use of electromagnetic waves to carry information.  We call them “radio waves”  Common wireless technologies – Infrared – Radio Frequency Electromagnetic Spectrum

ITE PC v4.0 Chapter 1 3 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Infrared Technology  Line of sight transmission  Unable to penetrate through walls  IRDA port (Infrared Direct Access) – used to exchange information between devices  Used by: – remote controls – wireless mouse and keyboard

ITE PC v4.0 Chapter 1 4 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Radio Frequency (RF) Technology  Signal able to transmit through walls  RF bands set aside for wireless devices, including cordless phones and computer peripherals  900 MHz – used by cell phones  2.4 GHz – Bluetooth technology – low speed, short range – can communicate with many devices at once  5 GHz – Wireless LAN – transmit at a higher level = greater distance – conform to standards

ITE PC v4.0 Chapter 1 5 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Benefits of Wireless  Mobility  Scalability – can be added to a network easily – use of “hotspots”  Flexibility – anytime, anywhere connectivity  Cost – inexpensive to install – reduced installation costs

ITE PC v4.0 Chapter 1 6 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Limitations/Risks of Wireless  Uses unlicensed regions of the RF spectrum – used by many different devices  Interference – cordless phones – microwaves  Security – easy access to the network – encryption/authentication helps with security issues

ITE PC v4.0 Chapter 1 7 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Wireless Technologies  WPAN – Wireless Personal Area Network – used for: mice keyboards PDAs

ITE PC v4.0 Chapter 1 8 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Wireless Technologies  WLAN – Wireless LAN – uses RF standards – conform to standards – connects through Wireless AP

ITE PC v4.0 Chapter 1 9 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Wireless Technologies  WWAN – Wireless WAN – coverage over large areas – cell phone network

ITE PC v4.0 Chapter 1 10 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public IEEE Wireless Standards  Define how wireless devices communicate  – wireless standards – group of all standards = Wi-Fi Wireless Fidelity  Wi-Fi Alliance – tests wireless devices from manufacturers

ITE PC v4.0 Chapter 1 11 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Components of a WLAN  Wireless client – any host that can participate in a wireless network  Access point (AP) – control access between wired and wireless networks

ITE PC v4.0 Chapter 1 12 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Components of a WLAN  Wireless Bridge – connects two wired networks through a wireless link – offers long range connectivity 25 miles – Uses unlicensed RF frequencies

ITE PC v4.0 Chapter 1 13 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Access Point  Antennas – increases output signal strength (gain) – receives the wireless signal – higher gain = increased distance  Directional antenna – concentrates signal in one direction – allows for greater distances  Omni-directional antenna – emits signal equally in all directions – used by most Access Points

ITE PC v4.0 Chapter 1 14 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Purpose of SSID  Service Set Identifier  Allows wireless components to connect to the WLAN – tells wireless devices which WLAN they belong to – tells devices whom then can talk to  All wireless devices must have same SSID to communicate with each other  Characteristics – case sensitive – alphanumeric characters – sent in the header of the frame

ITE PC v4.0 Chapter 1 15 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Ad-hoc Installation  Simplest form  Used to connect 2 or more wireless devices together in a peer to peer network  No Access Point (AP) needed  IBSS – Independent Basic Service Set – area covered by the Ad-hoc network

ITE PC v4.0 Chapter 1 16 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Infrastructure Installation  Used by larger networks  Uses an Access Point (AP) – makes sure all STAs have equal access  Each device must receive permission to communicate  BSS – Basic Services Set – area covered by a AP

ITE PC v4.0 Chapter 1 17 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Distribution System  ESS – Extended Service Set  Use of multiple Access Points  Each BSS should overlap by 10% – will help prevent loss of signal

ITE PC v4.0 Chapter 1 18 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Channels in a WLAN  Use of channels help to control conversations – allows multiple Access Points close to one another to function – each AP must be on different channel  Each channel capable of carrying a different conversation

ITE PC v4.0 Chapter 1 19 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public CSMA/CA  Carrier Sense Multiple Access with Collision Avoidance  Ensures collisions do not occur on a wireless network  Reserves a channel for communication – Device requests permission from AP (Request to Send–RTS) – If available, AP responds with all clear message Clear to Send Message (CTS) – CTS is broadcast to all other devices informs everyone the channel is being used –Upon completion of conversation Device that requested channel send ACK to AP ACK indicates to AP that channel can be used again ACK sent to other devices letting them know the channel can be used again

ITE PC v4.0 Chapter 1 20 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Configuring a Wireless Access Point  Modes – Specific to a device – Mixed Mode – supports multiple types of hosts decreases performance – supports more devices  SSID – used to identify the WLAN – all devices that participate must use the same SSID – SSID broadcast to everyone allows for easy detection  Wireless Channel – auto locate finds the least congested channel

ITE PC v4.0 Chapter 1 21 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Configuring a Wireless Client  Wireless host (STA) – device that contains a wireless NIC and wireless software – client configuration must match that of the Access Point  Windows XP – wireless client software – included as part of the operating system – can control most configurations

ITE PC v4.0 Chapter 1 22 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Configuring a Wireless Client  Using stand-alone software – supplied with the wireless NIC – includes enhanced functions  Not possible to allow both XP and the stand-alone software at the same time  Once software is installed, check connectivity – connection data rate – connection status – wireless channel used – ping

ITE PC v4.0 Chapter 1 23 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Wireless Security  No physical connection needed  Attacker can “tune into” your network just like tuning into a radio station  Easy access if all settings are set to default, so...  CHANGE THE SETTINGS – disable SSID – change default password – change default IP  But.. – SSID transmitted in clear text – still possible to learn the SSID

ITE PC v4.0 Chapter 1 24 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public MAC Address Filtering  Another security feature  Will limit access to your network  MAC address used to identify which device can connect to the wireless network – wireless AP looks up MAC in a list (database) – only those addresses listed will gain access

ITE PC v4.0 Chapter 1 25 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Security – Authentication  Controls who connects to the network  Permitted based on set of credentials  Helps to verify the “trustworthiness” of the device – usernames – passwords  Occurs before client is connected to WLAN

ITE PC v4.0 Chapter 1 26 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Open Authentication  On by default  Any and all clients can access AP  Should only be used on public wireless networks – Schools – Internet Café

ITE PC v4.0 Chapter 1 27 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public PSK (Pre-Shared Keys) Authentication  Both AP and client must have the same secret key or word  Here’s how it works: – AP sends random string of bytes to client – Client accepts it, encrypts it, and sends it back to AP – AP receives encrypted string, decrypts it – if decrypted string = original string  client is added

ITE PC v4.0 Chapter 1 28 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public EAP (Extensible Authentication Protocol)  EAP software must be installed on the client device  Client talks with RADIUS Server – Remote Authentication Dial-in User Services – server functions separately from the AP – server keeps a database of valid users – username and password checked by the server

ITE PC v4.0 Chapter 1 29 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Encryption  Process of transforming data so if intercepted, will still be unusable  WEP (Wired Equivalency Protocol) – advanced security feature – encrypts network traffic as it travels – 64 – 128 bits (letters and/or numbers) – AP and every device on the network must have the same WEP key

ITE PC v4.0 Chapter 1 30 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Traffic Filtering  Controls the type of traffic allowed across a WLAN  Able to block traffic based on: – IP Address – MAC Address – Port Numbers

ITE PC v4.0 Chapter 1 31 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Planning the WLAN  Determine the type of wireless standard – b, g, n operates at 2.4 GHz – travels farther than 5 GHz – Less equipment = lower cost  Determine layout – look at existing infrastructure – if using a, will it work with the newest standards??  Installation/Security – Total Cost of Ownership (TCO) – Site Survey signal strength possible interference  Backup/Updating Devices

ITE PC v4.0 Chapter 1 32 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Securing the AP  Basic Security – Changing values (SSID, usernames, passwords) – Disable Broadcast SSID – MAC Address filtering  Advanced Security – Encryption – Authentication – Traffic Filtering

ITE PC v4.0 Chapter 1 33 © 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 34 © 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 35 © 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 36 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public