ZyXEL Communications G-170S manual

ZyXEL G-170S 802.1 1g Wireless CardBus Card User ’ s Guide V ersion 1.00 Edition 1 1 1/2006[...]

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ZyXEL G-170S User’s Guide Copyright 3 Copyright Copyright © 2006 by ZyXEL Communications Corpo ration. The contents of this publication may not be reprod uced in any part or as a whole, transcribed, stored in a retrieval system, tran slated into any language, or transmitted in any form or by any means, el ectronic, mechanical , magnetic, optical[...]

ZyXEL G-170S User’s Guide 4 Federal Communications Commission (FCC) Interference Statement Federal Communications Commission (FCC) Interference S t atement The device complies with Part 15 of FCC rules. Operation is subject to the following two conditions: • This device may not cause harmful interference. • This device must accept any interfe[...]

ZyXEL G-170S User’s Guide Federal Com munications Commission ( FCC) Interf erence Statem ent 5 Certifications 1 Go to www .zyxel.com . 2 Select your product from the drop-d own list box on the ZyXEL home page to go to that product's page. 3 Select the certification you wish to view from this page. 注意 ! 依據 低功率電波輻射性電?[...]

ZyXEL G-170S User’s Guide 6 ZyXEL Limited Warranty ZyXEL Limited W arranty ZyXEL warrants to the original en d user (purchaser) that this product is free from any defects in materials or workmanship for a period of up to two (2) years from the date of purch ase. During the warranty period , and upon proof of p urchase, should the product have i n[...]

ZyXEL G-170S User’s Guide Customer Support 7 Customer Support Please have the following information r eady when you contact customer support. • Product model and serial number . • W arranty Information. • Date that you received your de vice. • Brief description of the problem and the steps yo u took to solve i t. METHOD LOCATION SUPPORT E[...]

ZyXEL G-170S User’s Guide 8 Customer Suppo rt POLAND info@pl.zyxel.com +48-22-5286603 www .pl.zyxel.com ZyXEL Communications ul.Emilli Plater 53 00-1 13 W arszawa Poland +48-22-5206701 RUSSIA http://zyxel.ru/support +7-095-542- 89-29 www .zyxel.ru ZyXEL Russia Ostrovityanova 37a S tr . Moscow , 1 17279 Russia sales@zyxel.ru +7-095-542-89-25 SP AI[...]

ZyXEL G-170S User’s Guide Table of Contents 9 T able of Content s Copyright .................................................. ................................................................ 3 Federal Communications Commissi on (FCC) Interference St atement ............... 4 ZyXEL Limited W arranty .......................... ....................[...]

ZyXEL G-170S User’s Guide 10 Table of Contents 2.2.3 WP A(2) ..... ................ ............. ............. ................ ............. ............. ............ 29 2.2.3.1 Encryption ... ................ ............. ................ ............. ................ ......... 29 2.2.3.2 User Authentication ......... ................ .....[...]

ZyXEL G-170S User’s Guide Table of Contents 11 Index ..................................... ..................................................... .............................. 77[...]

ZyXEL G-170S User’s Guide 12 Table of Contents[...]

ZyXEL G-170S User’s Guide List of Figure s 13 List of Figures Figure 1 Application: Infrastructure ... ............. ............. ............. ................ ............. 20 Figure 2 Application: Ad-Hoc ................... ................ ................ ................ ............. 20 Figure 3 Enable WZC ......... ................ .....[...]

ZyXEL G-170S User’s Guide 14 List of Figures Figure 39 Windows XP SP2: Wireless Net wor k Connection: No Security ............. 63 Figure 40 Windows XP: Wireless (network) properties: As sociation .................. ... 64 Figure 41 Windows XP: Wireless (network) pr operties: Authentic ation .... ............. 65 Figure 42 Windows XP: Prot ected [...]

ZyXEL G-170S User’s Guide List of Tables 15 List of T ables T able 1 ZyXEL U tility: System Tray Icon ........... ................ ................. ................ ... 22 T able 2 ZyXEL Utility : Menu Screen Summar y ..... ............ ................. ............ ....... 23 T able 3 Link Info ................ ................ ............. .[...]

ZyXEL G-170S User’s Guide 16 List of Tables[...]

ZyXEL G-170S User’s Guide Preface 17 Preface Congratulations on your purchase of the Zy XEL G-170S 802.1 1g Wireless CardBus Card. Y our G-170S is easy to install and configure. About This U ser's Guide This manual is designed to guide you th rough the configuration of yo ur G-170S for its various applications. Related Document ation • Sup[...]

ZyXEL G-170S User’s Guide 18 Preface Graphics Icons Key Wireless Access Point Computer Notebook Computer Server Modem Wireless Signal T ele phone Switch Router Internet Cloud[...]

ZyXEL G-170S User’s Guide Chapter 1 Getting Started 19 C HAPTER 1 Getting S t arted This chapter introduces the G-170S an d prepares you to use the ZyXEL utility . 1.1 About Y our G-170S The G-170S is an IEEE 802.1 1b/g compliant wireless LAN adapter . The following lists the main features of your G-170S. See the product specifications in the app[...]

ZyXEL G-170S User’s Guide 20 Chapter 1 Getting Started Figure 1 Application: Infrastructure 1.1.1.2 Ad-Hoc In case you prefer to set up a small independ ent wireless workgroup without an AP , use Ad- Hoc mode. Ad-hoc mode does not require an AP or a wired network. T wo or more wireless clients can communicate directly to each other . Figure 2 App[...]

ZyXEL G-170S User’s Guide Chapter 1 Getting Started 21 1.2 G-170S Hardware and Utility Inst allation Follow the instructions in the Quick S tart Guide to install the ZyXEL utility and make hardware connections . 1.3 Configuration Methods T o configure your G-170S, use on e of the following applications: • W ireless Zero Configuration (WZC) (rec[...]

ZyXEL G-170S User’s Guide 22 Chapter 1 Getting Started 1.5 Accessing the ZyXEL Utility After you install and start the ZyXEL utility , an icon for the ZyXEL utility appears in the system tray . Note: When the ZyXEL utility system tray icon displays, the G-170S is inst alled properly . When you use the ZyXEL utility , it automatically disables the[...]

ZyXEL G-170S User’s Guide Chapter 1 Getting Started 23 The following table describes the menus. 1.7 Connecting to a Wireless LAN The following sections show you how to associate with a network using the ZyXEL utility . Y ou can either manually connect to a network or configure a profile to have the G-170S automatically connect to a speci fic netw[...]

ZyXEL G-170S User’s Guide 24 Chapter 1 Getting Started Figure 7 ZyXEL Utility: Site Survey 4 T o join a network, either click an SSID in the table and then click Connect or double- click an SSID. 5 If the wireless security is activated for the sele cted wireless network, the Security Settings screen displays. This screen varies according to the n[...]

ZyXEL G-170S User’s Guide Chapter 1 Getting Started 25 Figure 9 ZyXEL Utility: Link Info[...]

ZyXEL G-170S User’s Guide 26 Chapter 1 Getting Started[...]

ZyXEL G-170S User’s Guide Chapter 2 Wireless LAN Network 27 C HAPTER 2 Wireless LAN Network This chapter provides backgro und in formation on wireless LAN network. 2.1 Wireless LAN Overview This section describes the wireless LAN network terms and applications. 2.1.1 SSID The SSID (Service Set Identity) is a unique name shared am ong all wireless[...]

ZyXEL G-170S User’s Guide 28 Ch apter 2 Wireless LAN Network 2.1.4 Super G The Super G technology works with IEEE 802.1 1 a/b/g products. It doubl es IEEE 802.1 1g performance by bond ing two 54Mbps channels and allo wing larger frames to be sent. IEEE 802.1 1g wireless LAN devices using Super G can transmit at up to 108 Mbps. 2.2 Wireless LAN Se[...]

ZyXEL G-170S User’s Guide Chapter 2 Wireless LAN Network 29 2.2.2.1 EAP Authentication EAP (Extensible Authentication Protocol) is an au thentication protocol that runs on top of the IEEE 802.1x transport mechanism in order t o su pport multiple types of us er authentication. By using EAP to interact with an EAP-compatib le RADIUS server , an acc[...]

ZyXEL G-170S User’s Guide 30 Ch apter 2 Wireless LAN Network The encryption mechanisms used for WP A(2) and WP A(2)-PSK are the same. The only difference between the two is that WP A(2)-PSK uses a simple common pa ssword, instead of user-specific credentials. The common-passwor d approach makes WP A(2)-PSK susceptible to brute-force password-gues[...]

ZyXEL G-170S User’s Guide Chapter 2 Wireless LAN Network 31 2.2.5 WP A(2) with RA DI US Application Example Y ou need the IP address of the RADIUS server , its port number (de fau lt is 1812), and the RADIUS shared secret. A WP A(2)-RADIUS appl ication example with an external RADIUS server looks as follows. "A" is the RADIUS server . &[...]

ZyXEL G-170S User’s Guide 32 Ch apter 2 Wireless LAN Network 2.4 Preamble T ype Preamble is used to signal that data is coming to the receiver . Short preamble increases performance as l ess time sending preamble means more time for sending data. All IEEE 802.1 1b/g compliant wire less adapters support long preamble, but not all support short pre[...]

ZyXEL G-170S User’s Guide Chapter 3 ZyXEL Utilit y Configuration 33 C HAPTER 3 ZyXEL Utility Configuration This chapter shows you how to configure your G-17 0S in wireless station mode. 3.1 The Link Info Screen When the ZyXEL utility starts, the Link Info screen displays, showing the current configuration and connection status of your G-170S. Fig[...]

ZyXEL G-170S User’s Guide 34 Chapter 3 ZyXEL Utility Configuration 3.1.1 T rend Chart Click T rend Chart in the Link Info scre en to display a screen as shown below . Use this screen to view real-time data traffic statistics. Figure 13 Link Info: T rend Chart T ransmissio n Rate This field displays the current transmission rate of the G-170S in m[...]

ZyXEL G-170S User’s Guide Chapter 3 ZyXEL Utilit y Configuration 35 The following table describes the labels in this screen. 3.2 The Site Survey Screen Use the Site Survey screen to scan for and connect to a wireless network automatically . Figure 14 Site Survey The following table describes the labels in this screen. Table 4 Link Info: Trend Ch [...]

ZyXEL G-170S User’s Guide 36 Chapter 3 ZyXEL Utility Configuration 3.2.1 Connecting to a WLAN Network Follow the steps below to connect to a WLAN network using the Site Survey screen. 1 Click Scan to search for all available wireless networks within range. 2 T o join a network, click an entry in the tabl e to select a wireless network and then cl[...]

ZyXEL G-170S User’s Guide Chapter 3 ZyXEL Utilit y Configuration 37 3.2.2.1 WEP Encryption Figure 15 Security Settings: WEP The following table describes the labels in this screen. Table 6 Security Settings: WEP LABEL DESCRIPTION WEP Select 64 Bit s , 128 Bit s or 152 Bits to activate WEP encryp tion and then fill in the related fields. Authentic[...]

ZyXEL G-170S User’s Guide 38 Chapter 3 ZyXEL Utility Configuration 3.2.2.2 WP A/WP A2 Note: WP A2 and WP A2-PSK are only availa ble in Windows XP and Windows 2000. Figure 16 Security Settings: WP A/WP A2 Key x (where x is a number between 1 and 4) Select this option if you want to manually en ter the WEP keys. Enter the WEP key in the field provi[...]

ZyXEL G-170S User’s Guide Chapter 3 ZyXEL Utilit y Configuration 39 The following table describes the labels in this screen. 3.2.2.3 WP A-PSK/WP A2-PSK Note: WP A2 and WP A2-PSK are only availa ble in Windows XP and Windows 2000. Figure 17 Security Settings: WP A-PSK/WP A2-PSK Table 7 Security Settings: WPA/WPA2 LABEL DESCRIPTION Encryption T ype[...]

ZyXEL G-170S User’s Guide 40 Chapter 3 ZyXEL Utility Configuration The following table describes the labels in this screen. 3.2.2.4 IEEE 802.1x Figure 18 Security Settings: 802.1x The following table describes the labels in this screen. Table 8 Security Settings: WPA-PSK/WPA2-PSK LABEL DESCRIPTION Encryption T ype The encryption mechanisms used f[...]

ZyXEL G-170S User’s Guide Chapter 3 ZyXEL Utilit y Configuration 41 3.2.3 Confirm Save Screen Use this screen to confirm an d save the security settings. Figure 19 Confirm Save Screen The following table describes the labels in this screen. Server CA Select a certificate aut ho rity (CA) that you trust and accept any certificates signed by the CA[...]

ZyXEL G-170S User’s Guide 42 Chapter 3 ZyXEL Utility Configuration 3.3 The Profile Screen A profile is a set of wireless para meters that you need to connec t to a wi reless ne twork. W ith a profile activated, each time you start the G- 170S, it automatically scans for the specific SSID and joins that network with the pre-defined wi reless secur[...]

ZyXEL G-170S User’s Guide Chapter 3 ZyXEL Utilit y Configuration 43 The following table describes the labels in this screen. 3.3.1 Adding a New Prof ile Follow the steps below to add a new profile. 1 Click Add in the Pr ofile screen. An Add New Profile screen displays as shown next. Click Next to continue. Table 11 Profile Screen LABEL DESCRIPTIO[...]

ZyXEL G-170S User’s Guide 44 Chapter 3 ZyXEL Utility Configuration Figure 21 Profile: Add New Profile The following table describes the labels in this screen. Table 12 Profile: Add New Profile LABEL DESCRIPTION Add New Profile Profile Name Enter a descriptiv e name in this field. SSID Select an available wireless device in the Scan Info table and[...]

ZyXEL G-170S User’s Guide Chapter 3 ZyXEL Utilit y Configuration 45 2 If you select the Infrastructure network type in the previous screen, skip to step 3 . If you select the Ad-Hoc network type in the previous scr een, a screen displays as follows. Select a channel number and wi reless LAN mode and click Next to continue. Figure 22 Profile: Wire[...]

ZyXEL G-170S User’s Guide 46 Chapter 3 ZyXEL Utility Configuration 3 If you select Infrastructure network type in the first screen, select WEP , WP A , WP A2 , WP A-PSK , WP A2-PSK or 802.1x from the drop-down list box to enable d ata encryption. If you select Ad-Hoc netw ork type in the first screen, you can only use WE P encryption method. Othe[...]

ZyXEL G-170S User’s Guide Chapter 3 ZyXEL Utilit y Configuration 47 Figure 25 Profile: Wireless Protocol 6 This read-only screen shows a summary of the new profile settings. V erify that the settings are correct. Click Save to save and go to the next screen. Click Back to return to the previous screen. Otherwise, click Exit to go back to the Prof[...]

ZyXEL G-170S User’s Guide 48 Chapter 3 ZyXEL Utility Configuration Figure 27 Profile: Activate the Profile 3.4 The Adapter Screen T o set the advanced feature s on the G-170S, click the Adapter tab. Figure 28 Adapter Screen The following table describes the labels in this screen. Table 14 Adapte r LABEL DESCRIPTION Adapter Setting T ransfer Rate [...]

ZyXEL G-170S User’s Guide Chapter 3 ZyXEL Utilit y Configuration 49 Power Saving Mode Select Maximum Power Saving or Fast Power Saving to save power (especially for notebook computers). This forces th e G-170S to go to sleep mode when it is not transmitting data. When you select Continuous Access Mode , the G-17 0S will never go to sleep mode. Sa[...]

ZyXEL G-170S User’s Guide 50 Chapter 3 ZyXEL Utility Configuration[...]

ZyXEL G-170S User’s Guide Chapter 4 Maintenance 51 C HAPTER 4 Maintenance This chapter describes how to unin stall or upgrade the ZyXEL utility . 4.1 The About Screen The About screen displays related version numbers of the G-170S. T o display the sc reen as shown below , click the about ( ) button. Figure 29 About The following table describes t[...]

ZyXEL G-170S User’s Guide 52 Chapter 4 Maintenance Figure 30 Uninstall: Confirm 3 Click Finish to complete uninstalling the softwa re and restart the computer when prompted. Figure 31 Uninstall: Finish 4.3 Upgrading the ZyXEL Utility Note: Before you uninst all the ZyXEL utility , take note of your current wireless configurations. T o perform the[...]

ZyXEL G-170S User’s Guide Chapter 4 Maintenance 53 6 Insert the G-170S and check the version numbers in the About screen to make sure the new utility is installed properly .[...]

ZyXEL G-170S User’s Guide 54 Chapter 4 Maintenance[...]

ZyXEL G-170S User’s Guide Chapter 5 Trou bleshoot ing 55 C HAPTER 5 T roubleshooting This chapter covers potential problems and the possible remedies. After each problem description, some instructions ar e provided to help you to diag nose and to solve the problem. 5.1 Problems S t arting the ZyXEL Utility 5.2 Problem with the Link Quality Table [...]

ZyXEL G-170S User’s Guide 56 Chapter 5 Troubleshooting 5.3 Problems Communicating With Other Computers Table 18 Troubleshootin g Communication Problem PROBLEM CORRECTIVE ACTION In wireless station mode, the computer with the G-170S installed cannot communicate with the other computer(s). In Infrastructure Mode • Make sure that th e AP and the a[...]

ZyXEL G-170S User’s Guide Appendix A Product Specifications 57 A PPENDIX A Product S pecifications Table 19 Product Specification s PHYSICAL AND ENVIRONMENTAL Product Name ZyXEL G-170S 802.1 1g Wireless CardBus Card Interface 3.3V 32-bit CardBus card S tandards IEEE 802.1 1b IEEE 802.1 1g Network Architectures Infrastructure Ad-Hoc Security 64/12[...]

ZyXEL G-170S User’s Guide 58 Appendix A Product Specifications Device Drivers Microsoft Windows 98 Second Edition, Windows ME, Windows 2000, Windows XP Roaming IEEE 802.1 1b/g compliant WEP 64/128/152-bit WEP encryption Table 19 Product Specification s (continued)[...]

ZyXEL G-170S User’s Guide Appendix B Management with Wireless Zero Configuration 59 A PPENDIX B Management with Wireless Zero Configuration This appendix shows you how to manage y our ZyXEL wireless LA N adapter using the W indows XP wireless zero configuration tool. Be sure you have the W indows XP service pack 2 installed on your computer . Oth[...]

ZyXEL G-170S User’s Guide 60 Appendix B Management with Wireless Zero Configuration Connecting to a Wireless Network 1 Double-click the network icon for wireless conn ections in the system tray to open the W ireless Network Connection S tatus screen. Figure 33 Windows XP SP2: System T ray Icon The type of the wireless network icon in W ind ows XP[...]

ZyXEL G-170S User’s Guide Appendix B Management with Wireless Zero Configuration 61 W indows XP SP1: In the W ireless Network Connection S tatus screen, click Properties and the Wir eless Ne tworks tab to open the Wir eless Networ k Connection Properties screen. Figure 35 Windows XP SP1: Wireles s Network Con nection S tatus 3 W indows XP SP2: Cl[...]

ZyXEL G-170S User’s Guide 62 Appendix B Management with Wireless Zero Configuration The following table describes the ic ons in the wireless network list. W indows XP SP1: Click Refresh to reload and search for available wireless devices within transmission range. Sel ect a wireless network in the A vailable networks list, click Configure and set[...]

ZyXEL G-170S User’s Guide Appendix B Management with Wireless Zero Configuration 63 If there is no security activated for the se lected wireless ne twork, a warning screen appears. Click Connect Anyway if wireless security is not your concern. Figure 38 Windows XP SP2: W ireless Networ k Connection: WEP or WP A-PS K Figure 39 Windows XP SP2: W ir[...]

ZyXEL G-170S User’s Guide 64 Appendix B Management with Wireless Zero Configuration Association Select a network in the Preferred networks lis t and click Properties to view or configure security . Figure 40 Windows XP : Wireless (netwo rk) properties: Association The following table describes the labels in this screen. Table 23 Windows XP: Wirel[...]

ZyXEL G-170S User’s Guide Appendix B Management with Wireless Zero Configuration 65 Authentication Click the Authentication tab in the Wir eless (network) prop erties screen to display the screen shown next. Th e fields on thi s screen ar e grayed out when the network is in Ad-Hoc mode or data encryption is disabled. Figure 41 Windows XP: Wireles[...]

ZyXEL G-170S User’s Guide 66 Appendix B Management with Wireless Zero Configuration Authentication Properties Select an EAP authen tication type in the W ireless (network) properties: Authentication screen and clic k the Properties button to display th e following screen. Protected EAP Properties Figure 42 Windows XP : Protected E AP Properties A[...]

ZyXEL G-170S User’s Guide Appendix B Management with Wireless Zero Configuration 67 The following table describes the labels in this screen. Smart Card or other Certificate Proper t ies Figure 43 Windows XP: Smart Card or other Certificate Properties Table 25 Windows XP: Protected EAP Properties LABEL DESCRIPTION V alidate server certificate Sele[...]

ZyXEL G-170S User’s Guide 68 Appendix B Management with Wireless Zero Configuration The following table describes the labels in this screen. Ordering the Preferred Networks Follow the steps below to manage y our preferred networks. 1 W indows XP SP2: Click Change the or der of pr eferr ed networks in the Wir eless Network Connection screen (see F[...]

ZyXEL G-170S User’s Guide Appendix B Management with Wireless Zero Configuration 69 Figure 44 Windows XP SP2: Wireles s Networks: Pr eferred Net works W indows XP SP1: In the W ireless Network Connection S tatus screen, click Properties and the Wireless Networks tab to open the sc reen as shown. Figure 45 Windows XP SP1: Wireles s Networks: Pr ef[...]

ZyXEL G-170S User’s Guide 70 Appendix B Management with Wireless Zero Configuration[...]

ZyXEL G-170S User’s Guide Appendix C Typ es of EAP Auth entication 71 A PPENDIX C T ypes of EAP Authentication This appendix discusses some popular authentication type s: EAP-MD5, EAP-TLS, EAP- TTLS, PEAP and LEAP . The type of authentication you use depends on the RADIUS ser ver or the AP . Consult your network administrator for more information[...]

ZyXEL G-170S User’s Guide 72 Appendix C Types of EAP Authentication PEAP (Protected EAP) Like EAP-TTLS, server-side certific ate authentication is used to establish a secure connection, then use simple username and p assword methods through the secured co nnection to authenticate the clients, thus hiding client identity . However , PEAP only supp[...]

ZyXEL G-170S User’s Guide Appendix C Typ es of EAP Auth entication 73 WP A(2) W i-Fi Protected Access (WP A) is a subset of the IEEE 802.1 1i standard. WP A2 (IEEE 802.1 1i) is a wireless security standard tha t defines stronger encryp tion, authentication and key manage ment than WP A. Key differences between WP A(2) and WEP are improved data en[...]

ZyXEL G-170S User’s Guide 74 Appendix C Types of EAP Authentication By generating unique data encryption keys for ev ery data packet and by creating an integrity checking mechanism (MIC), with TKIP and AES it is more difficult to decrypt data on a W i-Fi network than WEP and dif ficult for an intruder to break into the network. The encryption mec[...]

ZyXEL G-170S User’s Guide Appendix C Typ es of EAP Auth entication 75 Figure 46 WP A-PSK Authentication WP A(2) with RADIUS Ap plication Example Y ou need the IP address of the RADIUS server , its port number (de fau lt is 1812), and the RADIUS shared secret. A WP A(2) application example with an external RADIUS serv er looks as follows. "A&[...]

ZyXEL G-170S User’s Guide 76 Appendix C Types of EAP Authentication Security Parameters Summary Refer to this table to see what other secur ity parameters you should co nfigure for each Authentication Method/ key management prot ocol type. MAC address filters are not dependent on how you config ure these security features. Table 28 Wireless Secur[...]

ZyXEL G-170S User’s Guide Index 77 Index Numerics 802.1x 40 A About 51 activating a profile 47 Adapter 48 Ad-Hoc 45 Advanced Encryption St andard 29 , 73 advanced settings 48 antenna 19 antenna power output 57 authentication 37 authentication method auto 31 open system 31 shared key 31 Authentication T ype 31 auto authentication 31 C CA 71 Certif[...]

ZyXEL G-170S User’s Guide 78 Index L link informa tion 33 M Message Integrity Check 29 Message Integrity Check (MIC) 73 MIC 29 N network type 33 North America Contact Information 7 Norway , Contact Information 7 O Odyssey Client Ma nager 21 open system authentication 31 P Pairwise Master Key (PMK) 73 passphrase 28 , 37 passwor d phrase 28 Power S[...]

ZyXEL G-170S User’s Guide Index 79 U uninstalling ZyXEL Utility 51 upgrading ZyXEL Utility 52 important step 52 User Authentication 30 , 74 V voltage 57 W Web Site 7 WEP 28 , 37 manual setup 28 , 38 passphrase 28 , 37 WEP (Wired Equivalent Priva cy) 28 Wi-Fi Protected Access 29 , 73 Windows XP 21 wireless LAN channel 27 introduction 27 security 2[...]