Configuring the Client Adapter through
Windows CE .NET
This appendix explains how to configure and use the client adapter with Windows CE .NET.
The following topics are covered in this appendix:
•Preparing for Configuration (EAP-TLS and PEAP Only)
•Configuring the Client Adapter
•Associating to an Access Point Using Windows CE .NET
This appendix provides instructions for configuring the client adapter through Windows CE .NET (instead of through ACU). The "Overview of Security Features" section below describes the security options that are available for use with this operating system so that you can make an informed decision before you begin the configuration process. In addition, the appendix also provides basic information on using Windows CE .NET to specify the networks to which the client adapter associates.
Note The instructions in this appendix are specific to PPC 2003 devices. The same configuration parameters must be set on other Windows CE .NET devices; however, the procedure used to set those parameters may differ. If you require more information on configuring or using your client adapter with Windows CE .NET, refer to the documentation that came with your device and Microsoft's documentation for Windows CE .NET.
Overview of Security Features
When you use your client adapter with Windows CE .NET, you can protect your data as it is transmitted through your wireless network by encrypting it through the use of wired equivalent privacy (WEP) encryption keys. With WEP encryption, the transmitting device encrypts each packet with a WEP key, and the receiving device uses that same key to decrypt each packet.
The WEP keys used to encrypt and decrypt transmitted data can be statically associated with your adapter or dynamically created as part of the EAP authentication process. The information in the "Static WEP Keys" and "Dynamic WEP Keys with EAP" sections below can help you to decide which type of WEP keys you want to use. Dynamic WEP keys with EAP offer a higher degree of security than static WEP keys.
WEP keys, whether static or dynamic, are either 40 or 128 bits in length. 128-bit WEP keys offer a greater level of security than 40-bit WEP keys.
Static WEP Keys
Each device (or profile) within your wireless network can be assigned up to four static WEP keys. If a device receives a packet that is not encrypted with the appropriate key (as the WEP keys of all devices that are to communicate with each other must match), the device discards the packet and never delivers it to the intended receiver.
Static WEP keys are write-only and temporary; however, you do not need to re-enter them each time the client adapter is inserted or the Windows CE .NET device is reset. This is because the keys are stored (in an encrypted format for security reasons) in the registry of the device. When the driver loads and reads the client adapter's registry parameters, it also finds the static WEP keys, unencrypts them, and stores them in volatile memory on the adapter.
Dynamic WEP Keys with EAP
The new standard for wireless LAN security, as defined by IEEE, is called 802.1X for 802.11, or simply 802.1X. An access point that supports 802.1X and its protocol, Extensible Authentication Protocol (EAP), acts as the interface between a wireless client and an authentication server, such as a RADIUS server, to which the access point communicates over the wired network.
Two 802.1X authentication types are available for PPC 2003 and other Windows CE .NET 4.2 devices when you configure your client adapter through Windows CE .NET:
•EAP-TLS—This authentication type is enabled or disabled through the operating system and uses a dynamic session-based WEP key, which is derived from the client adapter and RADIUS server, to encrypt data. EAP-TLS requires the use of certificates for authentication.
RADIUS servers that support EAP-TLS include Cisco Secure ACS version 3.0 or later and Cisco Access Registrar version 1.8 or later.
•Cisco PEAP—Cisco PEAP authentication (also known as PEAP-GTC) is designed to support One-Time Password (OTP), Windows NT or 2000 domain, and LDAP user databases over a wireless LAN. It is based on EAP-TLS authentication but uses a password instead of a client certificate for authentication. Cisco PEAP is enabled or disabled through the operating system and uses a dynamic session-based WEP key, which is derived from the client adapter and RADIUS server, to encrypt data. Cisco PEAP requires you to enter your username and password in order to start the authentication process and gain access to the network. RADIUS servers that support Cisco PEAP authentication include Cisco Secure ACS version 3.1 or later.
Note To use Cisco PEAP authentication, you must have checked the Install Cisco PEAP Support check box during installation.
When you enable Require EAP on your access point and configure your client adapter for EAP-TLS or PEAP using Windows CE .NET, authentication to the network occurs in the following sequence:
1. The client associates to an access point and begins the authentication process.
Note The client does not gain access to the network until authentication between the client and the RADIUS server is successful.
2. Communicating through the access point, the client and RADIUS server complete the authentication process, with the password (PEAP) or certificate (EAP-TLS) being the shared secret for authentication. The password is never transmitted during the process.
3. If authentication is successful, the client and RADIUS server derive a dynamic, session-based WEP key that is unique to the client.
4. The RADIUS server transmits the key to the access point using a secure channel on the wired LAN.
5. For the length of a session, or time period, the access point and the client use this key to encrypt or decrypt all unicast packets (and broadcast packets if the access point is set up to do so) that travel between them.
Note Refer to the IEEE 802.11 Standard for more information on 802.1X authentication and to the following URL for additional information on RADIUS servers: http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/12cgcr/secur_c/scprt2/scrad.htm
Wi-Fi Protected Access (WPA)
Wi-Fi Protected Access (WPA) is a standards-based, interoperable security certification that greatly increases the level of data protection and access control for existing and future wireless LAN systems. It is derived from and compatible with the IEEE 802.11i standard. WPA leverages Temporal Key Integrity Protocol (TKIP) and Michael message integrity check (MIC) for data protection and 802.1X for authenticated key management.
WPA supports two mutually exclusive key management types: WPA and WPA-Pre-shared key (WPA-PSK). Using WPA key management, clients and the authentication server authenticate to each other using an EAP authentication method, and the client and server generate a pairwise master key (PMK). Using WPA, the server generates the PMK dynamically and passes it to the access point. Using WPA-PSK, however, you configure a pre-shared key on both the client and the access point, and that pre-shared key is used as the PMK.
WPA and WPA-PSK are supported in the Windows CE .NET 4.2 operating system. However, for these features to be available on your Windows CE .NET 4.2 device when you configure your client adapter through Windows CE .NET, the device manufacturer must have included the WPA supplicant in its operating system build.
Only 350 series cards that are running EAP authentication can be used with WPA. Refer to the "Configuring the Client Adapter" section for instructions on enabling WPA or WPA-PSK.
Note WPA must also be enabled on the access point. Access points must use Cisco IOS Release 12.2(11)JA or later to enable WPA. Refer to the documentation for your access point for instructions on enabling this feature.
Preparing for Configuration (EAP-TLS and PEAP Only)
If you are planning to use EAP-TLS or PEAP authentication with your Windows CE .NET device, you must make sure that your system meets certain requirements and obtain any necessary certificates before you can configure your client adapter. If you are not planning to use EAP-TLS or PEAP authentication, go to the "Configuring the Client Adapter" section.
Before you can enable EAP-TLS or PEAP authentication, your network devices must meet the following requirements:
•The Windows CE device must be a PPC 2003 or other Windows CE .NET 4.2 device.
•Client adapters must support WEP and use firmware version 5.40.10.
•Access points to which your client adapter will attempt to authenticate must use the following firmware versions or later: 11.23T (340 and 350 series access points), 12.2(4)JA (1100 series access points), or 11.54T (1200 series access points).
•All necessary infrastructure devices (for example, access points, servers, gateways, user databases, etc.) must be properly configured for the authentication type you plan to enable on the client.
Obtaining and Importing CA and User Certificates
EAP-TLS and PEAP authentication require the use of certificates. EAP-TLS requires both a Certificate Authority (CA) certificate and a user certificate while PEAP requires only a CA certificate. After you import the necessary certificates, you should not have to repeat this procedure until the certificates expire (at a time that is predetermined by the certificate server).
Note Chapter 8, provides instructions for viewing and removing certificates, if necessary.
Obtaining CA and User Certificates
If you have not yet obtained a CA certificate (for EAP-TLS or PEAP) and a user certificate (for EAP-TLS), follow these steps.
Step 1 Obtain the certificate file(s) (*.cer or *.crt) from your system administrator.
Step 2 Establish an ActiveSync connection between your laptop or PC and your Windows CE device.
Step 3 Open Windows Explorer on your laptop or PC.
Step 4 Copy the certificate file(s) and paste them into a folder under My Computer > Mobile Device.
Step 5 Follow the steps in the "Importing a CA Certificate" section and the "Importing a User Certificate" section to import the certificate file(s) for your Windows CE device.
Importing a CA Certificate
If you are planning to use EAP-TLS or PEAP authentication on your Windows CE .NET 4.2 device, follow these steps to import the CA certificate.
Step 1 Select Start > Programs > Cisco > CertMgr. The Certificate Manager window appears (see Figure E-1).
Figure E-1 Certificate Manager Window
Step 2 Make sure Trusted Authorities appears in the Certificate drop-down menu.
Step 3 Tap the Import button.
Step 4 The Certificate Manager Open window appears (see Figure E-2).
Figure E-2 Certificate Manager Open Window
Step 5 Tap the CA certificate file.
Step 6 The Certificate Manager window reappears with the name of the CA certificate server listed in the middle of the window.
Step 7 Tap OK to close the Certificate Manager.
Importing a User Certificate
If you are planning to use EAP-TLS authentication on your Windows CE .NET 4.2 device, follow these steps to import the user certificate.
Note As an alternative to the procedure below, you can use the Certificate Manager to import a user certificate. To do so, follow the steps in the "Importing a CA Certificate" section above, but make sure My Certificates (not Trusted Authorities) appears in the Certificate drop-down menu in Step 2 and tap the user certificate file (not the CA certificate file) in Step 5.
Step 1 Make sure that your Windows CE device has an ActiveSync link to a laptop or PC that is on the same network as the certificate server you want to use.
Step 2 Select Start > Programs > Cisco > Enroll. The Certificate Enrollment window appears (see Figure E-3).
Figure E-3 Certificate Enrollment Window
Step 3 Enter your username, password, and server name for your certificate server, which can be obtained from your system administrator, in the appropriate fields.
Step 4 Tap the Enroll button. The box at the bottom of the window indicates the status of the certificate enrollment by changing from Ready to Processing.
If the operation is successful, the following message appears: "A certificate has been added to your device."
Step 5 Tap OK to close the Certificate Enrollment window.
Configuring the Client Adapter
Follow these steps to configure your client adapter using Windows CE .NET.
Note These instructions assume you are using a Windows CE .NET 4.2 device (specifically a PPC 2003) with the WPA supplicant installed. If you use a Windows CE .NET 4.0 or 4.1 device or a Windows CE .NET 4.2 device without the WPA supplicant, the windows you see will look different than those shown in this section. Refer to version OL-1375-04 of this manual if you need instructions on configuring a client adapter through Windows CE .NET without the WPA supplicant.
Step 1 Make sure the client adapter is inserted in the Windows CE .NET device.
Step 2 Double-tap the ACU icon on your desktop or select Start > Programs > Cisco > ACU.
Step 3 On the Profiles window, select <External Settings> from the Select Active Profile drop-down menu.
Step 4 When prompted, tap OK. Then reset your Windows CE .NET device or eject and reinsert the client adapter.
Step 5 Tap OK to save your settings.
Step 6 Select Start > Settings > the Connections tab > Connections > the Advanced tab > Network Card. The Configure Wireless Networks window (Wireless tab) appears (see Figure E-4).
Figure E-4 Configure Wireless Networks Window (Wireless Tab)
Step 7 Tap the SSID of the access point to which you want the client adapter to associate from the list of wireless networks. If the SSID of the access point you want to use is not listed or you are planning to operate the client adapter in an ad hoc network (a computer-to-computer network without access points), tap Add New.
The Configure Wireless Network window (General tab) appears (see Figure E-5).
Figure E-5 Configure Wireless Network Window (General Tab)
Step 8 Perform one of the following:
•If you selected an SSID from the list of wireless networks, make sure the SSID appears in the Network name field.
•If you selected Add New, enter the case-sensitive SSID of the access point to which you want the client adapter to associate or the name of the ad hoc network in the Network name field.
Step 9 Check the This is a device-to-device (ad-hoc) connection check box if you are planning to operate the client adapter in an ad hoc network.
Step 10 Tap the Network Key tab. The Configure Network Authentication window (Network Key tab) appears (see Figure E-6).
Figure E-6 Configure Network Authentication Window (Network Key Tab)
Step 11 Choose one of the following options from the Authentication drop-down list:
•Open— Enables your client adapter, regardless of its WEP settings, to authenticate and attempt to communicate with an access point. This option is recommended if you want to use static WEP or EAP authentication without WPA.
•Shared—Enables your client adapter to communicate only with access points that have the same WEP key. Cisco recommends that shared key authentication not be used because it presents a security risk.
Note EAP-TLS does not work with shared key authentication because shared key authentication requires the use of a WEP key, and a WEP key is not set for EAP-TLS until after the completion of EAP authentication.
•WPA—Enables WPA, which enables your client adapter to associate to access points using WPA.
•WPA-PSK—Enables WPA Pre-shared key (WPA-PSK), which enables your client adapter to associate to access points using WPA-PSK.
Note Refer to the "Wi-Fi Protected Access (WPA)" section for more information on WPA and WPA-PSK.
Step 12 Choose one of the following options from the Data Encryption drop-down list:
•Disabled—Disables data encryption for your client adapter. This option is available only when Open or Shared has been selected for Authentication.
•WEP—Enables static or dynamic WEP for your client adapter. This option is recommended for use with open authentication.
•TKIP—Enables Temporal Key Integrity Protocol (TKIP) for your client adapter. This option is recommended for use with WPA and WPA-PSK.
Step 13 Follow these steps to enter a static WEP key if you are planning to use static WEP.
Note If you are planning to use EAP-TLS or PEAP authentication, which uses dynamic WEP, go to Step 15.
a. Make sure the The key is provided for me automatically check box is unchecked.
b. Obtain the WEP key for the access point (in an infrastructure network) or other clients (in an ad hoc network) from your system administrator.
c. Enter the WEP key in the Network key field. In order to communicate, the client adapter must use the same WEP key as the access point or other clients.
d. In the Key index field, select the number of the WEP key you are creating (1, 2, 3, or 4).
Note The WEP key must be assigned to the same number on both the client adapter and the access point (in an infrastructure network) or other clients (in an ad hoc network).
Step 14 If you enabled WPA-PSK, obtain the pre-shared key for the access point (in an infrastructure network) or other clients (in an ad hoc network) from your system administrator and enter it in the Network key field.
Note Your client adapter's pre-shared key must match the pre-shared key used by the access point (in infrastructure mode) or clients (in ad hoc mode) with which you are planning to communicate.
Step 15 Check the The key is provided for me automatically check box if you are planning to use EAP-TLS or PEAP authentication, which uses dynamic WEP keys.
Note This parameter is not available if you enabled WPA or WPA-PSK.
Step 16 Perform one of the following:
•If you are not planning to use EAP authentication, tap OK to save your settings and to add this SSID to the list of wireless networks (see Figure E-4). The client adapter automatically attempts to associate to the network(s) in the order in which they are listed. When the client adapter is associated to an access point, the word Connected appears to the right of the network name in the list of wireless networks.
•If you are planning to use EAP-TLS authentication, follow the instructions in the "Enabling EAP-TLS Authentication" section below.
•If you are planning to use PEAP authentication, follow the instructions in the "Enabling PEAP Authentication" section.
Enabling EAP-TLS Authentication
Follow these steps to prepare the client adapter to use EAP-TLS authentication, provided you have completed the initial configuration.
Step 1 Tap the 802.1x tab. The Configure Network Authentication window (802.1x tab) appears (see Figure E-7).
Figure E-7 Configure Network Authentication Window (802.1x Tab)
Step 2 Check the Use IEEE 802.1x network access control check box.
Step 3 Select Smart Card or Certificate in the EAP type drop-down box.
Step 4 If your Windows CE .NET device has more than one user certificate, tap the Properties button. On the Select Certificate window, select the user certificate that you want to use and tap OK.
Step 5 Tap OK to save your settings. The configuration is complete. The client adapter automatically attempts to associate to the network(s) in the order in which they are listed. When the client adapter is associated to an access point, the word Connected appears to the right of the network name in the list of wireless networks.
Step 6 Refer to the "Using EAP-TLS" section on page 6-4 for instructions on authenticating using EAP-TLS.
Enabling PEAP Authentication
Follow these steps to prepare the client adapter to use PEAP authentication, provided you have completed the initial configuration.
Step 1 Tap the 802.1x tab. The Configure Network Authentication window (802.1x tab) appears (see Figure E-8).
Figure E-8 Configure Network Authentication Window (802.1x Tab)
Step 2 Check the Use IEEE 802.1x network access control check box.
Step 3 Select Cisco PEAP in the EAP type drop-down box.
Note If the Microsoft PEAP supplicant is installed (rather than the Cisco PEAP supplicant), PEAP (rather than Cisco PEAP) appears in the EAP type drop-down box. Follow the instructions in your Microsoft documentation to configure your client adapter to use Microsoft PEAP.
Step 4 Tap the Properties button. The PEAP Properties window appears (see Figure E-9).
Figure E-9 PEAP Properties Window
Step 5 Make sure the Validate server certificate check box is checked if server certificate validation is required (recommended).
Step 6 Check the Connect only if server name ends in check box and enter the appropriate server name suffix in the text box below.
Note If you leave this field blank, you are prompted to accept a connection to the server to which your client adapter is connected during the authentication process.
Step 7 Make sure that the name of the certificate authority from which the server certificate was downloaded appears in the Trusted root certificate field. If necessary, tap the arrow on the drop-down box and select the appropriate name.
Note If you leave this field blank, you are prompted to accept a connection to the root certification authority during the authentication process.
Step 8 Check the Connect only if server is signed by specified trusted root CA check box if you want to ensure that the certificate server uses the trusted root certificate specified in the field above. This prevents the client from establishing connections to rogue access points.
Step 9 Perform one of the following:
•Check the Always try to resume Secure Session check box if you want the PEAP protocol to always attempt to resume the previous session before prompting you to re-enter your credentials.
•Uncheck the Always try to resume Secure Session check box if you want to be prompted to re-enter your username and password whenever your client adapter's radio becomes disassociated (for example, when the card is ejected, the radio is turned off, you wander out of range of an access point, you switch profiles, and so on).
Note Checking this check box gives you the convenience of not having to re-enter your username and password when your client adapter experiences momentary losses of association. The PEAP Session Timeout setting on the Cisco Secure ACS System Configuration - Global Authentication Setup window controls how long the resume feature is active (that is, the amount of time during which the PEAP session can be resumed without re-entering user credentials). If you leave your device unattended during this timeout period, be aware that someone can resume your PEAP session and access the network.
Step 10 Tap OK on each open window to save your settings. The configuration is complete. The client adapter automatically attempts to associate to the network(s) in the order in which they are listed. When the client adapter is associated to an access point, the word Connected appears to the right of the network name in the list of wireless networks.
Step 11 Refer to the "Using PEAP" section on page 6-5 for instructions on authenticating using PEAP.
Associating to an Access Point Using Windows CE .NET
Windows CE .NET causes the client adapter's driver to automatically attempt to associate to the first network in the list of wireless networks (see Figure E-4). If the adapter fails to associate or loses association, it automatically switches to the next network in the list of wireless networks. The adapter does not switch networks as long as it remains associated to the access point. To force the client adapter to associate to a different access point, you must select a different network from the list of available networks and tap OK.